My AP Biology Thoughts

AP Biology Russia Ukraine

Hopewell Valley Student Publications Network — Thu, 08 Jun 2023 09:00:00 -0500

Unit #: 8

EPISODE TITLE:

Welcome to My AP Biology Thoughts podcast, our names are Ramit Dasika, Flavio D’Attilio, Samy Leroux, Landon Schafer, Colin Fahmy and we are hosting this episode called Unit 8 Ecology AND Today we will be discussing The war between Ukraine and Russia has caused mass destruction to many ecosystems through bombings and other weaponry and how it relates to the AP Biology Curriculum.

Segment 1: Overview of Topic

War
The war between Ukraine and Russia has caused mass destruction to many ecosystems through bombings and other weaponry

Segment 2: Evidence that supports

It causes forest fires- Samy
During the process of runoff, the harmful chemicals are collected in rivers nearby. This causes the water sources contaminated due to chemical leakage from destroyed industrial plants-Ramit
During the Russia-Ukrainian War, the Russian soldiers damaged and looted fire engines, computers, and radiation monitoring equipment, while leaving mines and munitions spread across the exclusion zone.-Flavio
“In the Donbas region, wrecked sewage works gush their contents into rivers and damaged pipelines fill wetlands with oil.”- Landon
“Most of the exclusion zone was damaged by the invasion and may be contaminated with unexploded ordnance and mines,” according to Oleksandr Galushchenko, director of the biosphere reserve. The larger mammals that constantly move around the reserve – wolves, deer, brown bears, lynx, elk, and recently reintroduced bison – are at particular risk, he says.”-Samy
“The forests in the zone remain a radioactive tinderbox that, in the event of fires, could send radioactive isotopes on the winds towards Kyiv. The risks of that happening are now much greater, says the UNCG’s forest campaigner Yehor Hrynyk. With fire-fighting equipment looted and much of the exclusion zone dangerous for firefighters to enter, some 65,000 acres has burned since the invasion, and fires continue to smolder in underground peat.”-Colin
“Many industrial plants are damaged or abandoned;wrecked sewage works gush their contents into rivers; damaged pipelines are filling wetlands with oil; and toxic military scrap is spread across the land.”- Flavio
“A particular concern is the many coal mines abandoned after 2014. With pumping of water halted, they have so far released some 650,000 acre-feet of polluted mine water into the environment, according to Serhii Ivaniuta of the National Institute for Strategic Studies in Kyiv.”- Landon
Russian bombardment of a steel plant could have released tens of thousands of tons of hydrogen 5sulfide into the Sea of Azov.- Samy
As a result of the damage from the war, Environmentalists say that in looking to recovery, the Ukrainian government is prioritizing big projects over natural restoration. The government is looking for maintaining power in the government and becoming a global leader. The nations are forgetting about the ecological damage.- Ramit

Segment 3: Connection to the Course

Pollution in the environment could cause microorganisms to die, which could subsequently cause a trophic cascade in which producers die off causing other higher tr213ophic levels to drop in population as well.- Flavio
Nuclear power plants being targeted; can cause climate change which kills ectotherms
“The biodiversity is being drastically affected due to intense deforestation and habitat destruction with potential implications for wildlife.”- Landon
“The ecosystem services supplied will likely be strongly damaged since deforestation will decrease the capacity of the ecosystems to regulate air pollution or climate. Soil degradation will hamper food production, and landscape aesthetics, cultural heritage and social cohesion destruction drastically affects cultural services.”- Colin

https://time.com/6222865/ukraine-environmental-damage-russia/

https://e360.yale.edu/features/ukraine-russia-war-environmental-impact#:~:text=Early%20on%2C%20Russia%20invaded%20the,the%20plant%20in%20recent%20weeks.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (Enter your closing Tag-line)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/
Ice spice (That Landon a munch)

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Single Use Plastics

Hopewell Valley Student Publications Network — Thu, 08 Jun 2023 09:00:00 -0500

My AP Biology Thoughts

Unit #: 8- Disruptions to Ecosystems

---------------------------------------------------------------------------------------------------------------------------------------------------

EPISODE TITLE: Single Use Plastics

Jaiden: Welcome to My AP Biology Thoughts podcast, our names are Jaiden, Adam, and Reena and we are your hosts for this episode called Unit 8, Human Stupidity and Single Use Plastics. Today we will be discussing how single use plastics cause disruptions to the ecosystem and how it relates to the AP Biology Curriculum.

The Podcast will be broken up into three segments. The first segment will show the general overview of single-use plastics and the second segment will show how these plastics impact the environment and why it relates to the AP Biology Curriculum. Finally, segment three will discuss how we can contribute and reduce single use plastics.

Segment 1: Overview of Topic

Plastic pollution has become one of the most pressing environmental issues
According to the Environmental Protection Agency, Americans generated 35.7 million tons of plastic in the United States.
Single use plastics are plastics that are used for a brief period of time, before they are thrown away. These include plastic straws, spoons, bottles, and bags
Microplastics are extremely small pieces of plastic debris. They are generally about five millimeters, or approximately the diameter an eraser on a #2 pencils, in length to be considered microplastics

Segment 2: Just how much harm is plastic causing

Some plastics such as Chlorinated plastics is harmful for the soil around it along with water sources making it harder for organisms to grow
It takes 1,000 years for a plastic bag to degrade in a landfill. However, the plastic does not degrade completely but instead becomes microplastics that absorb toxins and continue to pollute the environment.
An estimated 13 million plastic tons are thrown into the ocean each
These small plastic particles may harm our health once they have entered our bodies. Plastic products contain chemical additives. A number of these chemicals have been associated with serious health problems such as hormone-related cancers, infertility and neurodevelopmental disorders like ADHD and autism.
There are now 5.25 trillion macro and micro pieces, weighing up to 269,000 tonnes. This is because every day, around 8 million pieces of plastic make their way into our oceans.
Unlike some other kinds of waste, plastic doesn't decompose. That means plastic can stick around indefinitely, wreaking havoc on marine ecosystems. Some plastics float once they enter the ocean, though not all do.
Thousands of seabirds and sea turtles, seals and other marine mammals are killed each year after ingesting plastic or getting entangled in it. Endangered wildlife like Hawaiian monk seals and Pacific loggerhead sea turtles are among nearly 700 species that eat and get caught in plastic litter.

Segment 2: Connection to the Course

This is related to fitness and the survival rate of organisms since the plastic decreases the survival rate of most organisms.
This also connects to ecosystems and how plastic interrupts them by harming members of the ecosystem.
The harm of organisms can impact the biodiversity of an organism which is our current unit.
Climate change reduces the biodiversity of an ecosystem by causing some animals, who can’t adapt to the changing temperatures to become extinct, impacting the entire food web.

Segment 3: Plastic bag debate

The debate on manufacturing of plastic bags. The current plastic bag has 75% less plastic than it did 20 years ago largely due to climate concerns. However this makes the plastic bags less durable and unlike 20 years ago plastic bags are no longer able to be reused. According to the federal government 2/3rds of the plastic bags from grocery stores are being used. So would it be better to produce plastic bags with more plastic in order for them to be reused or try to minimize the plastic needed for the bags to function.
Plastic bags banned in New Jersey (May 4th 2022)
Most plastic waste into the ocean isn’t caused by just the United States. An estimated 80% of ocean plastic waste is caused by Asia from their rapid urbanization. This can cause plastic waste to be related to foreign policy and how other countries can influence the environmental impact of other nations. The United States is the next biggest culprit but has improved in recent years.
Alternate solutions. Examples include: Reusable bags, paper/polylactic acid (these two are biggest alternative material), community service.

Reena: Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Remember: Do something drastic and cut the plastc!

Don’t forget to Subscribe to our Podcast and our YouTube channel along with Connect with us on Twitter (@thehvspn)

---------------------------------------------------------------------------------------------------------------------------------------------------

Sources:

Link 1, Link 2, Link 3, Link 4, Link 5, Link 6, Link 7. Link 8. Link 9

Music Credits: (either stated at end of video or written)

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Isle Royale Predator and Prey Relationships

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: The Isle of Wolves

Welcome to My AP Biology Thoughts podcast, our names are Olivia, Anushka, Mea, and Hana and we are your hosts for the Unit 8 Ecology-the Isle Royale Study podcast. Today we will be discussing the Isle Royale Study and how it relates to the AP Biology Curriculum.

Segment 1: Overview of the Isle Royale Study

Camping —> DOCTAH guise —-> isle royale —-> us listening to him talk :)

Segment 2: Evidence that supports the Isle Royale Study

Winter controls the ticks (kills them all if cold temperature)
Provide ex of trophic cascading
Predator prey talk abt it
Human interaction/interference (trails, being on/off)
Coloring of the wolves
Talk abt winter study (break island into quadrants and take populations #’s)

Segment 3: Connection to the Course

Predator-prey relationship:
Trophic structure: a flow of energy between organisms in an ecosystem
Energy flow
Parasitic
Importance of genetic diversity

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Bee Conservation

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Conservation of Bees

Welcome to My AP Biology Thoughts podcast, my name is Alex, here with Raelynn and Samiyah and we are your hosts for today’s episode, coming from Unit 8 - our Ecology unit. Today we will be discussing bee conservation.

Why are bees important to the environment?

According to the US Department of Agriculture: “One out of every three bites of food in the United States depends on honey bees and other pollinators. Honey bees pollinate $15 billion worth of crops each year, including more than 130 fruits and vegetables. Managed honey bees are important to American agriculture because they pollinate a wide variety of crops, contributing to food diversity, security and profitability.”
Pollinators - support plant populations
Food crops as well as wild plants

Why are bee populations declining?

“Declines in bumble bee species in the past 60 years are well documented in Europe, where they are driven primarily by habitat loss and declines in floral abundance and diversity resulting from agricultural intensification.” (According to researchers from the University of Stirling)
loss of habitats because of farming + urbanization
Habitat fragmentation can impact surviving populations through genetic isolation (which causes inbreeding and makes population less genetically diverse, making them more susceptible to diseases)
University of London (an issue of Apidologie): habitat loss is the “most universal and high impact factor driving bee declines.”

https://www.ehn.org/monoculture-farming-is-not-good-for-the-bees-study-2639154525.html

https://abcnews.go.com/International/monoculture-farming-modern-day-agriculture-killing-bees-scientists/story?id=80536659

Climate Change
University of London (an issue of Apidologie): Change in temperature and weather patterns due to climate change can significantly impact bee populations
Additionally, loss of habitat due to rising sea levels can also cause negative impacts
stats
University of Maryland: October 2018 - April 2019: 40% of honey bee colonies in US died
Many other insect populations in decline, evidence of a possible 6th mass extinction (“biological annihilation”)
Pesticide use massively impacting bee populations and reproductive rates
44% fewer offspring in bee populations affected by pesticides in both youth and adulthood, according to scientists at the University of California
These pesticides (neonicotinoids), while banned in many wealthier countries, are still used in and exported to low and middle income countries
Varroa mite
Colony Collapse Disorder

Bee conservation attempts:

Researcher Winfree from Rutgers University
Formal protection of threatened species - according to data an approximated 95,000 insects in general are in risk of extinction, however only 771 have been evaluated for candidacy on the global Red List. No bee species is listed under the US Endangered Species Act, even though many species are known to be rare and declining at a steep rate. An important step for the conservation of bees requires them to be identified as organisms that require protection
The National Resources Conservation Service, an agency that operates under the United States’ Department of Agriculture, has begun working with “agricultural producers to combat future declines by helping them to implement conservation practices that provide forage for honey bees while enhancing habitat for other pollinators and wildlife and improving the quality of water, air and soil.”
Some of these measures include planting cover crops, wildflowers, and native grasses, along with improving management of grazing lands.
University of Nevada: researchers identified a disease (American foulbrood (AFB)) that affects honeybees. In order to protect the bees, researchers have found a virus that attacks the disease and have successfully lowered AFB levels.

Connection to the course:

Trophic cascades - no bees = plant species dying off
Keystone species
Harder to farm reliably without pollinators

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Sources:

Bees. National Wildlife Federation. (n.d.). Retrieved December 8, 2021, from https://www.nwf.org/Educational-Resources/Wildlife-Guide/Invertebrates/Bees.

Brown, M. J. F., & Paxton, R. J. (n.d.). The conservation of bees: A global perspective - Apidologie. SpringerLink. Retrieved December 8, 2021, from https://link.springer.com/article/10.1051/apido/2009019.

Goulson, D., Lye, G. C., & Darvill, B. (2008). Decline and conservation of Bumble Bees. Annual Review of Entomology, 53(1), 191–208. https://doi.org/10.1146/annurev.ento.53.103106.093454

Guardian News and Media. (2021, November 18). Bee-harming pesticides exported from EU despite ban on outdoor use. The Guardian. Retrieved December 8, 2021, from https://www.theguardian.com/environment/2021/nov/18/bee-harming-pesticides-exported-from-eu-after-ban-on-outdoor-use.

Kate Baggaley | Published Nov 23, bees pesticides Pollinators Science, Bees, Pesticides, Pollinators, & Science. (2021, November 22). Pesticides leave a lasting mark on pollinating bees. Popular Science. Retrieved December 8, 2021, from https://www.popsci.com/science/bees-pesticide-fertility/.

Ramaswamy, P. by D. S., & T, G. (2017, February 21). Reversing pollinator decline is key to feeding the future. USDA. Retrieved December 8, 2021, from https://www.usda.gov/media/blog/2016/06/24/reversing-pollinator-decline-key-feeding-future.

UMDRightNow. (n.d.). US beekeepers lost over 40% of colonies last year, highest winter losses ever recorded. EurekAlert! Retrieved December 8, 2021, from https://www.eurekalert.org/news-releases/612063.

Winfree, R. (n.d.). The conservation and restoration of wild bees. https://doi.org/10.1111/(issn)1749-6632

Woodward, A. (2019, June 21). Last year, 40% of honey-bee colonies in the US died. but bees aren't the only insects disappearing in unprecedented numbers. Business Insider. Retrieved December 8, 2021, from https://www.businessinsider.com/insects-dying-off-sign-of-6th-mass-extinction-2019-2.

Birds of Paradise Mating Rituals

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Birds of Paradise Mating Rituals

Welcome to My AP Biology Thoughts podcast, my name is Xavier and I am with Celine and Sofie and we are your hosts for Unit 8 Ecology-Birds of Paradise Mating Rituals. Today we will be discussing Birds of Paradise Mating Rituals and how it relates to the AP Biology Curriculum.

We want to thank our sources for the information presented in this podcast episode today which include National geographic and BBC Earth. You can find the citations and links to these sources in the show notes.

Segment 1: Overview of Bird

The birds of paradise are some of the most fascinating birds in the world, from their wide range of behaviors and striking coloration of the males, I would love to ask you some specific questions about them. I have looked over many different species and their behavior, but I am particularly interested in the elaborate mating displays performed by male birds of paradise.
Of course, let me begin with a bit of background on the species. Birds of paradise are members of the family Paradisaeidae (Para-dice-see-a-die), which researchers think evolved on the island of New Guinea. The family is comprised of 43 species, most found on the island of New Guinea. Two species are found only in the Moluccan Islands to the west of New Guinea, and four others are found mainly in northeastern Australia. The family of birds includes astrapias, manucodes, paradisaeas, parotias, riflebirds, and sicklebills.

Segment 2: Evidence that supports Animal Behavior within the Birds of Paradise

I know many species of birds are sexually dimorphic but what does this mean for the bird-of-paradise
Yes, this means the males and females have different appearances. So the males have elaborate feather patterns that they use in their mating displays while the females of these species have a more dull and camouflaged appearance
So while the females are watching the Males perform these displays what is their key concern when choosing which male to mate with?
The female choice appears to be based on the vigor of the males’ display meaning their physical strength and health. Which can be seen in the condition and color of his feathers.
So the female chooses a vigorous mate, ensuring that her offspring will also be relatively healthy.
Exactly, the strongest, most brightly-feathered males have a better chance of attracting the females, while less attractive males may be overlooked.
I was most interested in a species of male Superb bird-of-paradise with their dark black cape feathers and almost like a “psychedelic smiley face.” The way he snaps his tail rhythmically slowly, flashing a breastplate of iridescent like feathers. I’m sure the female’s prefer their beautiful feathers.
Like I had mentioned it really depends on what the female wants to pass on to her children. This is their key concern when mating. Impressive as it is, the male’s beauty is impractical. Excessively long tail feathers might be great for attracting mates, but they aren’t exactly useful for survival. In fact, it’s easy to see how they might be a hindrance.
So how did these features evolve seen as the males need them for mating but doesn’t survival play a role?
Well, when resources are plentiful and there are few predators, females don’t need the males to defend them, provide food, or help raise young. They can be picky when it comes to choosing a mate which leaves the males to work hard to impress the females. This is why sexual selection is so relevant in the bird-of-paradise

Segment 3: Connection to the Course

Now you may be thinking to yourself, how does this relate to the AP Bio Curriculum
Well...the birds of paradise mating ritual is a great example of courtship behavior
This is a behavior that results in reproduction, and in this case specifically through the visual and auditory stimuli that birds provide to the females
This behavior is innate meaning the animals don’t need to learn it, it just comes through genetics
Tieing back to the evolution unit as well, the elaborate plumage of the males is thought to have evolved through the evolutionary process of sexual selection
Sexual selection can be shown by the females choosing mates on the basis of their desirable behavioral and anatomic traits, including color. After mating, the female returns to her nest and raises her offspring alone
Darwin’s theory of sexual selection suggests that traits can also evolve in a population if they improve an individual’s ability to attract more or better mates, even if those same traits are a detriment to survival in the long term. If natural selection explains evolution driven by the competition for survival, then sexual selection explains evolution driven by the competition for mates.
This island has very few natural predators paving way for a specific type of sexual selection known as “female choice”

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Source Credits:

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Chimps in Uganda

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Chimps in Uganda

Welcome to My AP Biology Thoughts podcast, my name is kyle along with my handsome cohosts Shrithik, saahtih and gabe and we are your hosts for this episode , Unit 8 Ecology-Chimps in Uganda. Today we will be discussing Chimps and how they relate to the AP Biology Curriculum.

Segment 1: Overview of CHIMPS

Chimps in Uganda
98% share dna with humans
They move around and live in communities of individuals similar to humans
Don't travel in groups like gorillas or other monkeys
Around 1500 chimps in uganda live in 13 different communities inside the khabale forest with 5000 total in the country
Type 1 survivorship rate
K-selected species

Segment 2: Evidence that supports CHIMPS

“You can also track chimps in Kyambura Gorge, Kalinzu Forest, Budongo Forest and in the Semliki Valley. Most of our Uganda holidays focus on Kibale, which has a very high success rate for sightings, and the atmospheric Kyambura Gorge in Queen Elizabeth National Park, where sightings are less certain but the scenery is spectacular.”

People have the hobby of following the chimps
Watching these communities shows the similarities of our survivorship and how they are K selected -
K selected mean long term babies taking care of infants
Type 1 species
Population growth (exponential vs logarithmic)
Natural limiting factors of population - Habitat loss, leopards
How human activity affects chimp population - Hunting for bushmeat, pet trade and poaching and deforestation

Segment 3: Connection to the Course

These chimps relate to topic 8.3, population ecology in the AP biology curriculum.
The chimps provide an example of organisms changing in order to respond to their environment as they have opposable thumbs like humans in order to help grasp and climb trees which indirectly helps them obtain energy
The fact that the chimps have large group sizes, small body sizes and dietary flexibility increases their adaptive capacity to contribute to the success of their population in their habitat.
The chimps eat figs, fruits, nuts, insects and even bark

Thank you for listening to this episode of My AP Biology Thoughts. And another thanks to our sources, lonely plant.com, responsible travel, and worldwildlife.com. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. And that's all folks and remember keep yo pimps close keep your chimps closer.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Leatherback Sea Turtles

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Disappearance of Costa Rican Leatherback Sea Turtles

Welcome to My AP Biology Thoughts podcast, my name is Beth Hooks, Emilie Sawicki, and Nick Bailey, and we are your hosts for episode # called Unit 8 Ecology-Costa Rican Leatherback Sea Turtles. Today we will be discussing the disappearance of Costa Rican Leatherback Sea Turtles and how it relates to the AP Biology Curriculum.

Segment 1: Overview of Costa Rican Leatherback Sea Turtles Disappearing

Leatherback sea turtles are one of the most ancient reptiles, as well as the most endangered sea turtles. Their habitat spans from the North Atlantic to the south pacific. Their lifespan is estimated to be 50 years or more. They feed on open ocean prey such as jellyfish and salps (NOAA.org).
Their nesting beaches are generally located in tropical latitudes, especially in Trinidad and Tobaago, the West-Indies, Gabon, Costa Rica, and on the Pacific coast of Mexico (NOAA.org).
The greatest threats worldwide are incidental capture in fishing gear, hunting of turtles, and collection of eggs for human consumption. Climate change, loss and degradation of nesting and foraging habitat, ocean pollution, and vessel strikes also pose a threat to the population (NOAA.org).
The Leatherback Sea Turtles are listed as endangered under the Endangered Species Act (NOAA.org).

Segment 2: Evidence that supports Costa Rican Leatherback Sea Turtles Disappearing

The turtles have had a 40% mortality rate in the returning adult population over the last 8 years. This data was obtained by fitting turtles with satellite transmitters and following their migration. Many disappear, and it is believed that mostly because they get stuck in fishing lines (World Turtle Trust).
Projects that monitor nesting sites conduct nightly census work and fit nesting turtles with Passive Integrated Transponders. Projects that protect nests from poachers attempt to maximize the number of hatchlings that survive (World Turtle Trust).

Segment 3: Connection to the Course

The jellyfish population is increasing due to rising global temperatures. This suggests that energy sources are not the problem. The population curve of a predator generally follows the population curve of their prey, so if the jellyfish population increases, this means that the turtle population should increase. However, since so much ocean pollution is present in the form of plastic bags and turtles often mistake them for jellyfish, the jellyfish population may be increasing due to less predation (Lamb, 2017).
Climate change has caused new predators to migrate to places where sea turtles are. This has begun to cause a trophic cascade in some environments that affects the phosphorus content of the sea grass (BurkHolder, Heithaus, Fourqurean, Wirsing, Dill, 2013).
Additionally, the migration of these turtles is an innate behavior. An innate behavior is a behavior that's genetically hardwired in an organism and can be performed in response to a cue without prior experience
At this point, the leatherback turtles have great opportunity to increase as a population, but due to density independent factors, which are unrelated to the size of the population, their population is unable to increase and move towards their carrying capacity. Some examples include human interference, climate change, and natural disasters. So, as the population continues to decrease, these factors will continue to be detrimental towards the population and the sea turtles will have a greater risk of becoming extinct.
And finally, the disappearance of the Costa Rican Leatherback Sea Turtles is just another reminder of the detrimental impact that humans have on the earth and the environments on it. Our footprint is impacting so many ecosystems, environments, and species, and causing many of them to become endangered and even extinct.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Marine Life on the Catalina Coast

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Marine Life on the Catalina Coast

Welcome to My AP Biology Thoughts podcast, our names are Sofia, Addie, Gillie, and Diana, and we are your hosts for the episode called Unit 8 Ecology- Marine Life on the Catalina Coast. Today we will be discussing Marine Life on the Beautiful Catalina Coast and how it relates to the AP Biology Curriculum. We want to thank our sources for the information presented in this podcast episode today which you can find the citations and links to these sources in the show notes.

Segment 1: Overview of Catalina Coast

Have you ever heard of the film Step Brothers? Perhaps… the Catalina Wine Mixer? While this is a great film in movie history, it does not correctly portray the true biodiversity of the Catalina Coast.
Now that you’re speaking about it, I remember looking up the Catalina Coast a while back and getting really intrigued by all of the stuff I was finding. I went down a rabbit hole for like three hours. I didn’t even know there was that much to look at. I might have to plan a vacation there.
I’m not going to lie I tend to stay away from the water because to quote Raven “I can’t swim”
And not to mention all the animals…. The ocean is a mystery that I do not wanna explore
But nonetheless, here we are today learning about the insane vastness of biodiversity
The Catalina Coast is located 23 miles off the coast of Southern California. If you’re taking a helicopter, you can get to the Catalina islands in 15 minutes. It is a part of the Channel Islands archipelago and is one of the four southern channel islands

Segment 2: Evidence that supports Marine Life on the Catalina Coast

Catalina Coast is the home of the Blue Cavern Onshore State Marine Conservation Area
If I remember correctly, Katy Perry says, “nothing comes close to the (I’m sure) Blue Cavern Onshore State Marine Conservation Coast”, and that includes humans, as it is a conservation
For the record, Sofia is not remembering this line correctly, but the idea is there.
More than 60 endemic species… meaning they are only found in the Catalina Coast region
Conservationists are working to preserve these endemic species to maintain the genetic diversity of this region
Ensuring that each species can adapt to environmental factors
Since Sofia wanted to quote Katy Perry, I’ll quote a super underground artist that you guys definitely wouldn’t know…. They’re called the Four Preps…… They sang a song called 26 miles (Santa Catalina)
So anyway, they talk about how it's only 26 miles from Cali baby and it's full of romance.
There are several types of species on Catalina Island. This includes different types of seals, such as the Phoca vitulina, or the harbor seal. The island also includes different types of snakes, lizards, frogs, and more.
My favorite sea animal is the sea lion. Does the Catalina Coast have those too?
Of course they do! The California Seal Lion, or the Zalophus Californianus, are one of the many species included in the Catalina Coast’s environment.

Segment 3: Connection to the Course

8.6 biodiversity
The biological variety and variability of life in a given ecosystem
Since the Catalina Coast is home to so many species, it indicates that there is a lot of biodiversities
The high level of biodiversity makes it so that the organisms can better respond to changes in their environment

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Cheers to the Catalina Coast!!!!!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Sources:

https://www.catalinaconservancy.org/index.php?s=news&p=article_357 (Catalina Conservancy)

https://www.lovecatalina.com/blog/post/sea-eight-things-know-catalina-underwater/ (Love Catalina Blog)

https://www.catalinaconservancy.org/index.php?s=wildlife&p=animal_species

https://fiveable.me/ap-bio/unit-8/biodiversity/study-guide/UQxfkl91v4pCcoar2qMD (Fiveable Study Guide)

https://www.lovecatalina.com/island-info/catalina-island/where-is-catalina-island/

https://www.amnh.org/research/center-for-biodiversity--conservation/what-is-biodiversity (AMNH Research Article)

https://www.youtube.com/watch?v=3dPaeUGrmdA (26 miles, The four preps)

The Great Pacific Garbage Patch

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: Pacific Garbage Patch and Its Impacts on Wildlife

Welcome to My AP Biology Thoughts podcast, my name is Angelina and my name is Emily and we are your hosts for the Unit 8 Ecology podcast on the Great Pacific Garbage Patch and Its Impacts on Wildlife. Today we will be discussing the Garbage Patch’s harmful effects on aquatic life and how it relates to the AP Biology Curriculum.

https://www.nationalgeographic.org/encyclopedia/great-pacific-garbage-patch/

Segment 1: Overview of Pacific Garbage Patch and Its Impacts on Wildlife

Background info:

The patch is a vortex of plastic waste and debris which is very calm and stable but surrounded by four currents that sweep debris into the center
Two distinct collections of debris, the Western and Eastern Garbage Patches
Pacific: Garbage is spun and linked together by the North Pacific Subtropical Convergence Zone, where warm water ( South ) meets cool water ( Arctic )
Much of the debris is not biodegradable and has taken a significant toll on the aquatic wildlife
Most of the debris is plastic, which is not biodegradable but rather breaks down into microplastic particles

Segment 2: Evidence that supports how the Patch Harms Wildlife

https://theoceancleanup.com/great-pacific-garbage-patch/

According to National Geographic, oceanographers and ecologists discovered that about 70% of marine debris sinks to the ocean floor, so the patch may also be an underwater heap of trash
Marine debris is known to be harmful to wildlife
Ex: Loggerhead sea turtles often mistake plastic bags for jellyfish
Ex: Albatrosses mistake plastic pellets for eggs and feed them to their chicks, which then die of starvation or ruptured organs
Ex: Seals and other animals get entangled in abandoned nets and other waste
hear about turtles a lot because of many companies movements to stop using straws, but we dont always hear about the other species being affected so it is definitely important to learn about these organisms as well
BIG ONE: Marine debris can disturb marine food webs
As microplastics collect near the ocean’s surface, they block sunlight which prevents plankton and algae to grow
Many organisms depend on these producers for food
Since they are at the foundational levels of the food web, when they are negatively impacted, the whole web is as well

Segment 3: Connection to the Course

Energy flow: Affects all wildlife (trophic structure)
Kills species, leaving less energy in ecosystem
If organisms consume garbage, the organisms feeding on them will be indirectly feeding on garbage
Bioaccumulation
Impacts humans as well
We should all do little things to help the environment

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Rhino Poaching in South Africa

Hopewell Valley Student Publications Network — Tue, 21 Dec 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Ecology

EPISODE TITLE: South African Rhino Poaching

Welcome to My AP Biology Thoughts podcast, my name is Keenan Wallace and I am your host for this episode called Unit 8 Ecology-Threatened Rhinos in South Africa. Today we will be discussing South African Rhino Poaching and how it relates to the AP Biology Curriculum.

Segment 1: Overview of Rhino Poaching

numbers poached rising in recent years:
13 Rhinos poached in 2007, peaked in 2015
1175 Rhinos killed in south africa in 2015 (more than 3 a day),
number poached has since declined with 394 killed in 2020
Rhino population has decreased from 1 million in the 1800s to only 27,000 in the wild today.
Rhinos are a keystone species: They play an integral role in their ecosystem and many other species in the ecosystem depend on their presence

Segment 2: Evidence that supports dangers of rhino poaching

Rhinos are so large that they actually Geo-form: change the land around them
Rhinos often wallow in mud to keep cool and ward off insects.
This helps maintain waterholes
When the rhinos get out they track the fertile, nutrient rich soil that accumulates in waterholes far and wide, distributing the nutrients.
Rhino dung supports other species and food chains
Rhino dung fertilizes soil
Dung beetles lay their eggs in rhino dung, which also supports species that eat the beetle larvae
A number of bird species rely on Rhino dung for insects and seeds.
Rhinos support fly and tick species as well as animals that eat them, like terrapins (a kind of turtle) and oxpeckers (the iconic symbiotic relationship)
Keep grass short, allowing plant species that can’t survive among long grass to thrive.

Segment 3: Connection to the Course

Without rhinos, all of these roles would be left unfilled and with its foundation gone the ecosystems would begin to collapse. (keystone species)
When you hear about rhino conservation, this is why it matters.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Sources:

“Vanishing Rhinos - The Impact of Rhino Poaching on the South African Ecosystem. (n.d.). The Scientista Foundation.” The Scientista Foundation, http://www.scientistafoundation.com/lifestyle-blog/-vanishing-rhinos-the-impact-of-rhino-poaching-on-the-south-african-ecosystem. Accessed 1 Dec. 2021.

“Poaching Numbers | Conservation | Save the Rhino International.” Save The Rhino, https://www.facebook.com/savetherhinointernational/, https://www.savetherhino.org/rhino-info/poaching-stats/. Accessed 1 Dec. 2021.

“Why Are Rhinos Important for Ecosystems? - Africa Geographic.” Africa Geographic, https://www.facebook.com/Africa.Geographic, 25 May 2020, https://africageographic.com/stories/why-are-rhinos-important-for-ecosystems/.

Examples of Evolution: Toxic River Fish

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: Natural Selection of the Tomcod against Pollutants

Welcome to My AP Biology Thoughts podcast, our names are Celine, Xavier, and Sofie and we are your hosts for this episode called Unit 7 Natural Selection: Examples of Evolution-Toxic River Fish. In episode 120, we will be discussing the Toxic River Fish and how it relates to the AP Biology Curriculum.

We want to thank our sources for the information presented in this podcast episode today which include national geographic and NPR. You can find the citations and links to these sources in the show notes.

Segment 1: Overview of Toxic River Fish

To begin with the overview, the species of fish we will be discussing today are the tomcod
This species of fish lives in the waters of New Jersey and New York, usually found in the Hudson River where pollutants and chemicals such as polychlorinated biphenyl was dumped between 1947-1976 by General Electric companies
Therefore they developed a gene the resulted in an immunity

Segment 2: Evidence that supports Evolution Toxic River Fish

We can see the evolution of Toxic River fish from the molecular Evolution that was changing in DNA sequences.
When the pollutants entered the hudson river it resulted in 95% of the fish developing liver tumors.
The toxins from the electric company entered the nucleus of cells and For some fish it caused a distortion of DNA instructions. This would cause some to most of the fish in the river to get sick and die.
By chance, the Toxic River Fish had a version of that gene that tolerated the PCB and toxins
The toxic river fish evolved to handle dangerous chemicals that were dumped in the river and Overtime the toxic river fish that had the resistant gene did better than the fish without it
Technically they’re not mutants, but the chemicals did give one genetic group an advantage over the others
This is where survival of the fittest played a role, the fish that could resist toxins would have a higher rate of survival than those without out resistance
The ability to resist the toxins caused the toxic river fish to lose some ability to cope with natural stressors like low oxygen or abnormally high temperatures but they still had advantage above other fish

Segment 3: Connection to the Curriculum

Biology is the study of biotic organisms, and focuses on the dynamic and behavior. Evolution is 1/12 characteristics of biology.
It connects to the course because it distinctly shows evolution through natural selection
Natural Selection: is the process to which an individual is selected to survive because of different phenotypes.
We can see that the toxic river fish fit to survive in the polluted ecosystems, as they adapted to the environment because of their specific phenotype.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Joyce, C. (2011, February 17). Toxic Avengers: Pollution Drove Fish Evolution. NPR.

https://www.npr.org/2011/02/17/133842089/toxic-avengers-pollution-drove-fish-evolution

Minard, A. (2011, February 19). Hudson River Fish Evolve Toxic PCB Immunity. National Geographic.

https://www.nationalgeographic.com/science/article/110217-hudson-river-pcb-fish-evolution-water

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Examples of Evolution: The Three-Spine Stickleback

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: The Threespine Stickleback

Welcome to My AP Biology Thoughts podcast, our names are Beth, Gillie, and Addie and we are your hosts for Unit 7: Examples of Evolution- The Threespine Stickleback. In episode 119, we will be discussing The Threespine Stickleback and how it relates to the AP Biology Curriculum.

Segment 1: Overview of Threespine Stickleback

The Threespine stickleback fish live in the ocean and in lakes. The fish who live in the lake have been separated from the ocean sticklebacks for thousands of generations. Although there is a difference between ocean and lake sticklebacks, all freshwater sticklebacks can vary in shape and size depending on habitat. Scientists looked into the differences between lake and ocean sticklebacks by taking 50 fish from each population and comparing them.

Segment 2: Evidence that supports Threespine Stickleback

Freshwater sticklebacks and ocean sticklebacks have a number of different physical characteristics. For example, Ocean Sticklebacks are generally much larger. They also differ in body length, spine length (and number), fin shapes, number of lateral plates (Genetic Science Learning Center, 2017, August). The scientists observed that the average number of lateral plates for ocean sticklebacks was 33. On the other hand, the average number of lateral plates was 5 in the lake stickleback. Additionally, Michael Bell ran an experiment where he determined just how fast this evolution was occurring. He tracked the genes of stickleback fish in lakes in Alaska and determined the speed at which evolution occurred (in just a decade) (Robert Sanders, M. R., & Sanders, R., 2021, June 21). More interesting, however, is the fact that fish evolved convergently across the globe due to similar conditions, despite being isolated for decades (Shen, H., 2012, April 04).

Segment 3: Connection to the Course

The Threespine Stickleback demonstrates natural selection and adaptation in the environment, which directly relates to section 7.1 and 7.2. The data of how lake and ocean sticklebacks have adapted over time is a prime example of fitness. The environment of the lake and the ocean are different, and as a result, the lake stickleback has evolved to better suit this body of water. The evolution of the Threespine Sticklebacks caused by natural selection in different environments connects to 7.1 and 7.2.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

References

Genetic Science Learning Center. (2017, August 1) Meet the Threespine Stickleback. Retrieved

October 13, 2021, from https://learn.genetics.utah.edu/content/evolution/meet

Robert Sanders, M. R., & Sanders, R. (2021, June 21). Stickleback fish provide genetic road map for rapid evolution. Retrieved from https://news.berkeley.edu/story_jump/stickleback-fish-provide-genetic-road-map-for-rapid-evolution/

Shen, H. (2012, April 04). Stickleback genomes reveal path of evolution. Retrieved from https://www.nature.com/articles/nature.2012.10392

Examples of Evolution: Plants and Birds

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: Babiana ringens

Welcome to My AP Biology Thoughts podcast, my name is Raelynn and my name is Samiyah and we are your hosts for Unit 7: Examples of Evolution - Plants and Birds. In episode 118, we will be discussing the plant Babiana ringens and how it has evolved to attract sunbirds.

Segment 1: Overview of Babiana ringens and evolution to attract birds

The Babiana ringens plant in South Africa evolved in such a way that increases the chance of Nectarine famosa, or the malachite sunbird - their main pollinators- to stop by and drink nectar out of their flowers. In the certain region that these plants reside, most sunbirds avoid predators by staying away from the ground- as such, the Babiana ringens evolved to create a small perch, making it easier for birds to drink their nectar, and thus pollinate them, which in turn increased their evolutionary fitness.

Segment 2: Evidence that supports the evolution of Babiana ringens to attract pollinators

Through a study conducted by botanist Spencer Barrett from the University of Toronto Canada, along with a team of researchers, they found that the sunbirds in the specific region of South Africa in which the plants with the perches reside used the perches to pollinate the plants, and were their main pollinators.
They went on to study other Babiana ringens plants across South Africa and found that they didn’t have the perches, and after studying them for some time, realized that their main pollinators weren’t the sunbirds that require the perches to make pollination easier. As such, the perch was an adaptation to the environmental pressures (of their main pollinators having been sunbirds).

Segment 3: Connection to the Course

The interactions between Babiana ringens and sunbirds demonstrate the concept of evolution and natural selection. The flowers with the perch were more “fit” for the environment since it encouraged the birds to perch on them and pollinate the flower. As a result, the Babiana ringens with the genes for the perch were able to both outlive and outpopulate those without perches. Over time, the gene for flowers without this stem faded away from the gene pool, and it became characteristic of Babiana ringens to have upside-down flowers.

Introduction

Welcome to My AP Biology Thoughts podcast, my name is Raelynn and my name is Samiyah and we are your hosts for this episode on Plants and Birds. Today we will be discussing Babiana ringens - a flower that has evolved to grow upside down to attract sunbirds, with data from BBC, nerdfighteria, and the National Center for Biotechnology Information. We would also like to thank Botanist Spencer Barett from the University of Toronto and his team of researchers for their findings on this subject!

Quick Overview of Babiana Ringens

Babiana ringens, also known as rat’s tail, is a plant native to Cape’s Province, South Africa. It is a bright red perennial plant that flowers during the winter seasons (because it’s a rebel). This plant is pollinated mostly by Nectarine famosa, or the malachite sunbird, which is named after its striking and vivid colors.

Babiana ringens are known for their peculiar and unique shape. Unlike other plants, its stem dips downwards towards the ground while the flower remains right-side-up.

How did this plant species evolve to grow this way, and what role did the malachite sunbirds play?

Evolution of Babiana Ringens

German botanist Rudolf Marloth was the first to note that the Babiana ringens had seemed to evolve some sort of perch at their bottoms. To explore this odd phenomenon, botanist Spencer Barett from the University of Toronto, along with a team of researchers, conducted extensive research to understand the history behind the unique perches characteristic of the Babiana ringens plants.

They found that the plants in one specific geographic region only had one primary pollinator- the malachite sunbirds. The upside-down shape of the stem attracted sunbirds due to its efficient shape, which allowed the birds to land on the perch while simultaneously feeding on nectar. As a result, the Babiana ringens with the perches had a greater likelihood of being pollinated by the sunbirds, thus increasing their evolutionary fitness. The researchers continued their research by studying other Babiana ringens plants across South Africa in order to see if the trends were repeated in other locations.

They found that while the Babiana ringens in the first location had perches, those in the other locations didn’t. After studying these plants for a period of time, the researchers noted that while the main pollinators of the plants in the first location were limited to the malachite sunbirds, the plants in the other locations had a greater variety of pollinators. Their study found that “Sunbird visitation rates were positively correlated with perch length in the seven populations of B. ringens from which data on these parameters were collected” (see Table 1 and Fig. 4). As a result, they were able to conclude that the reason the plants in the other locations didn’t grow upside down with perches was because there simply weren’t any environmental pressures that they had to adapt to. In the case of the plants with the perches, they had to adapt to a limited selection of pollinators, and in doing so, evolved to grow upside down.

Connection to the AP Bio Curriculum:

These interactions between Babiana ringens and the malachite sunbirds demonstrate the concept of evolution and natural selection, from 7.1 and 7.2, in the AP Biology curriculum. The flowers with the perch possessed a greater fitness for the environment because its shape was more ideal for pollination. As a result, the Babiana ringens with the genes for the perch were able to both outlive and outpopulate those without perches. Over time, the gene for flowers without this stem faded away from the gene pool, and it became characteristic of Babiana ringens in certain areas to have upside-down flowers.

Thank you for listening to this episode of My AP Biology Thoughts! For more student-run podcasts and digital content, make sure that you visit www.hvspn.com. Thank you!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Citations:

B;, de Waal C;Barrett SC;Anderson. “The Effect of Mammalian Herbivory on Inflorescence

Architecture in Ornithophilous Babiana (Iridaceae): Implications for the Evolution of a Bird Perch.” American Journal of Botany, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/22615309/.

Carpenter, Jennifer. “Plant Has Evolved a Specialist Bird Perch.” BBC News, BBC, 6 Sept. 2011,

www.bbc.com/news/science-environment-14788701.

De Waal, Caroli, et al. “The Natural History of Pollination and Mating in Bird-Pollinated Babiana

(Iridaceae).” Annals of Botany, Oxford University Press, Feb. 2012, www.ncbi.nlm.nih.gov/pmc/articles/PMC3278289/.

“Nerdfighteria Wiki.” The Plant That Grows Perches for Birds, nerdfighteria.info/v/0g2XDm1t12g/.

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Examples of Evolution: One Skink, Five Skink, Egg Skink, Live Skink

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: One Skink, Five Skink, Egg Skink, Live Skink

Welcome to My AP Biology Thoughts podcast, my name is Diana along with Sofia and Saahith and we are your hosts for Unit 7: Examples of Evolution-The Three Toed Skink- and I know what you’re thinking…. nope this is not derogatory or a slur. In episode 117, we will be discussing the species the Three Toed Skink and how it relates to the AP Biology Curriculum. We want to thank our sources for the information presented in this podcast episode today which include Reptiles Magazine, National Geographic, Eurekalert.org, syfi.com, phys.org, and sciencedaily.com. You can find the citations and links to these sources in the show notes.

Segment 1: Overview of The Three Toed Skink (Diana)

The three toed skink, aka Saiphos equalis, is found in eastern Australia, primarily in New South Wales and Queensland. The three-toed skink is sometimes mistaken for a snake, eats crawling insects and worms, and is active at night. The three toed skink is a “bimodally reproductive species” WHATS THAT this means that some lay eggs and some give birth. Dr. Whittington, from the School of Life and Environmental Sciences and Sydney School of Veterinary Science at the University of Sydney in the article “Biologists observe a three-toed skink lay eggs and give birth to a baby,” says, “Put in the context of evolutionary biology, being able to switch between laying eggs and giving live birth could allow animals to hedge their bets according to environmental conditions." There are at least 150 evolutionary transitions from egg-laying to live-bearing in vertebrates. To elaborate on this, Sofia will share the interesting evidence of evolution of the Three Toed Skink.

Segment 2: Evidence that supports The Three Toed Skink (Sofia)

Thank you, Diana, for that beautiful introduction to our beloved skinks. In the article, “Which Came First, the Lizard or the Egg”, Dr. Camilla Whittington from the University of Sydney skink research team describes how the earliest vertebrates were egg-layers, but that over thousands of years, embryos remained inside their mother’s for longer, until some began live births. WHAAAAATTTT?? The Three-toed skinks are an example of a species that have evolved to perform both reproduction methods of egg-laying and live births. Get yourself a skink who does both. Direct observation studies have revealed that the skink species located on the warm weathered coasts of New South Wales lay eggs rather than performing live birth. On the contrary, the skinks located in the cold weathered mountains of South Wales give live births. Scientists suggest that mothers in warm climates lay eggs to conserve their own bodies’ resources, while mothers in cold climates protect their young by keeping them inside the oven for longer. Additionally, evolutionary records show that nearly 100 reptile lineages have independently made the transition from egg-laying to live birth in the past, which supports that these skinks transition to adapt to their environment. On to Saahith my HANDSOME best buddy, who has some very wonderful connections between the three-toed sinks and our lovely evolution principles.

Segment 3: Connection to the Course (Saahith)

These skinks relate to topic 7.2,natural selection , 7.6 evidence of evolution, and 7.7 common ancestry in the AP Biology Curriculum. In the course, it is taught that evolution is supported by scientific evidence from many disciplines (geographical, geological, physical, biochemical, and mathematical data) the Three toed skink is an example of geographical evidence as skinks in warmer areas lay eggs and skinks in colder areas give birth to live younger. The warmer areas lay eggs in order to conserve body resources and live longer and produce more offspring. The colder areas give birth to live young because they want them to stay inside the adult in order to grow more and stay in a warm environment before being out in the cold. This is an example of natural selection as the baby skinks are kept in the parent skink in order to become more developed since they will be in a cold environment which makes it harder for them to live and maintain homeostasis of their body temperature. The skinks in these cold areas that laid eggs have eventually died off since they are not well suited for the environment and provide inadequate young that are unable to survive in the cold. WEAKKKKK !! Also it is believed skinks and snakes common vertebrates at first laid eggs but overtime with that vertebrate evolving at least 115 times, giving birth to live young became more and more common. The skinks in different areas most likely arrived from a common ancestor. To prove it we would need a comparison of DNA nucleotide sequences or amino acid sequences that would provide evidence of evolution and common ancestry.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (Remember… one skink, five skink, egg skink, live skink)! Ay and for my people out there, remember, always keep it a hundo. Get that 5. Goodbye.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Notes on topic:

https://phys.org/news/2010-09-scientists-evolution-action.html

One of 3 reptiles to have diff methods of reproduction in diff places
Lay eggs in Sydney, australia and coastal areas of New South Wales
Give birth to live young in Northern Highlands of New South Wales
Resembles small snake with mini legs, nocturnal
Intermediate skinks that retain eggs internally for longer. Live young birthers evolved from these
Giving birth to live young is advantage in cold areas

https://www.syfy.com/syfywire/bizarre-lizard-is-evolving-right-nowhttps://www.syfy.com/syfywire/bizarre-lizard-is-evolving-right-now

Earliest vertebrates laid eggs
Lizards and snakes evolved at least 115 times
Egg laying population in sydney is a transitional form from egg laying to live birth

https://reptilesmagazine.com/three-toed-skinks-ability-to-give-birth-and-lay-eggs-may-signal-evolutionary-shift/

Skinks may be in the midst of evolutionary shift between being an egg-later and a livebearer
“Bimodally reproductive” : species can lay eggs or give live births
Is the first known vertebrate to perform both in a single litter (clutch)
May be intermediate form between animals that lay eggs and those that give birth
Camilla Whittington: direction of skink evolution is not known yet
Egg-laying is more advantageous in certain areas
Oviparous S. equalis is an intermediate form between true oviparity and viviparity

https://www.nationalgeographic.com/animals/article/100901-science-animals-evolution-australia-lizard-skink-live-birth-eggs

Mystery of how young get nourishment before birth during live baby reproduction
In egg-laying species the embryo gets nourishment from the yolk, but calcium absorbed from the shell is also important for nutrients
The shells of the eggs thin, so the embryos can breathe until the live babies are born covered with only thin membranes
But thinner shell has less calcium… can cause deficiencies for young reptiles
Uterus secretes calcium that becomes incorporated into the embryo
Eggs are more vulnerable to external threats (weather and predators)
Internal fetuses are more taxing on the mother
Mothers in warm climates lay eggs to conserve their own bodies’ resources
Mothers in cold climates protect their young by keeping them inside for longer

https://www.nationalgeographic.com/animals/article/100901-science-animals-evolution-australia-lizard-skink-live-birth-eggs

Skink species lays eggs on the coast but births babies in the mountains
Yellow-bellied three-toed skinks along warm coastal lowlands of New South Wales lay eggs
Three-toed skinks living in New South Wales higher, colder mountains give birth to live young
Evolutionary records show nearly a hundred reptile lineages have independently made the transition from egg-laying to live birth in the past
About 20% of all living snakes and lizards give birth to live young only
Mothers in warm climates lay eggs to conserve their own bodies’ resources
Mothers in cold climates protect their young by keeping them inside for longer

https://www.eurekalert.org/news-releases/737125

Researchers at University of Sydney observed a female skink who gives birth to live babies, give birth to three eggs, then give a live birth from the same pregnancy only weeks later
Dr Whittington: "The earliest vertebrates were egg-layers, but over thousands of years, developing embryos in some species were held inside the body for longer, until some animals began to give live birth. People mostly think about humans and other mammals giving birth. But there are many species of reptile that give birth, too."

https://www.sciencedaily.com/releases/2019/04/190402215619.htm

Works Cited

Rayne, E. (2020, April 10). Thought evolution was ancient? this lizard is evolving, like, right now. SYFY WIRE. Retrieved October 14, 2021, from https://www.syfy.com/syfywire/bizarre-lizard-is-evolving-right-now.

Edwards, L. (2010, September 6). Scientists watch evolution in action. Phys.org. Retrieved October 14, 2021, from https://phys.org/news/2010-09-scientists-evolution-action.html.

Staff, S., & Staff, A. U. T. H. O. R. S. (2020, May 1). Three-toed skink's ability to give birth and lay eggs may signal evolutionary shift. Reptiles Magazine. Retrieved October 14, 2021, from https://reptilesmagazine.com/three-toed-skinks-ability-to-give-birth-and-lay-eggs-may-signal-evolutionary-shift/.

Handwerk, B. (2021, May 4). Evolution in action: Lizard moving from eggs to live birth. Animals. Retrieved October 14, 2021, from https://www.nationalgeographic.com/animals/article/100901-science-animals-evolution-australia-lizard-skink-live-birth-eggs.

SydneyUni_Media. (n.d.). Which came first, the lizard or the egg? EurekAlert! Retrieved October 14, 2021, from https://www.eurekalert.org/news-releases/737125.

Biologists observe a three-toed skink lay eggs and give birth to a live baby. (2019, April 02). Retrieved October 14, 2021, from https://www.sciencedaily.com/releases/2019/04/190402215619.htm

Examples of Evolution: Darwin’s Finches

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: Unit 7: Darwin’s Finches

Welcome to My AP Biology Thoughts podcast, my name is Shrithik Sekar, Kyle Mason, Gabe Moriello, and I am your host for Unit 7: Examples of Evolution, Darwin’s Finches. In episode 116, we will be discussing this topic and how it relates to the AP Biology Curriculum.

“We want to also thank our sources for the information presented in this podcast episode today which include (Britannica, Galapogosisland.org, and Crash course Biology on Youtube). You can find the citations and links to these sources in the show notes.”

Segment 1: Overview of Darwin's finches

What are Darwin's finches?

Who is darwin? - Geologist and Biologist, who formed the theory of natural selection. Known for his contributions to Science of evolution. He studied many finches which were found in the galapagos islands located 1,000 km off the coast of Ecuador
What were the finches? - These finches were a Group of 18 different species found in the Galapagos island. Darwin found the finches were all closely related with small direct observations that he made during his time in the Galapagos islands
What did he study? -During his studies while in the Galapagos islands, he concluded the speciation of the finches which is known as the experiment of Darwin’s finches
How does it relate to evolution? - It relates to evolution because it is an example of Direct observation

Segment 2: Evidence that supports Darwin's finches

Connection direct observation evolution

What is direct observation of evolution? - Through observation, in small population sizes, it can be found many changes of one species to then create many subspecies. Through direct observation of evidence in almost every species. THis idea had to do with the last universal ancestor, how all species are alike in many ways and all stemmed from the same ancestor. These finches dna is super similar, but these small differences of dna created a difference in appearance which was found ny darwin.
( This begs the question of ) Why are the finches an example of evolution? All 18 species of Darwin’s Finches were originally one finch species on the coast of south america. However, Darwin discovered that this species branched off into 18 different species on the Galapagos islands depending on the finches’ environment
What Key pieces of evidence did darwin find? - Darwin found the difference, fruit eating finches had wide beaks, insect eating finches had narrow beaks, and based on different factors of each finches environment each species had a different characteristic change. - GO TO Image

Segment 3: Connection to the Course

The 5 pieces of evidence - of evolution.

How do these ideas of evolution connect to our Biology class?

( Relates to AP bio curriculum 7.2 - Natural Selection)

( 7.4 - Population Genetics

(7.6 - Evidence of evolution

(7.7 - Common Ancestry

Direct observation is only one example of evolutionary evidence
5 other examples - Fossils, Geological evidence, Change in DNA, Homologous structures
All apart of either natural or physiological selection
Natural selection is a part of the 5 fingers of evolution ( Sexual Selection, Genetic Drift, Gene flow, Mutation)
Darwin’s finches show that adaptive evolution among the finch populations - the finches evolved different beak types depending on which food they ate, showing how natural selection is a factor in pushing populations to evolve

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Ceeeyaaa!!!!!!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Citations:

Desmond, A. J. (n.d.). Charles Darwin. Encyclopædia Britannica. Retrieved October 27, 2021, from https://www.britannica.com/biography/Charles-Darwin.

Darwin's finches. Galapagos Conservation Trust. (2019, December 3). Retrieved October 27, 2021, from https://galapagosconservation.org.uk/wildlife/darwins-finches/.

crashcourse. (2012, June 11). Evolution: It's a thing - crash course biology #20. YouTube. Retrieved October 27, 2021, from https://www.youtube.com/watch?v=P3GagfbA2vo.

crashcourse. (2018, October 1). Darwin and natural selection: Crash course history of science #22. YouTube. Retrieved October 27, 2021, from https://www.youtube.com/watch?v=dfsUz2O2jww.

Examples of Evolution: Coywolves

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: The Evolution of Coywolves

Keenan: Welcome to My AP Biology Thoughts podcast, my name is Keenan Wallace and I am your host for this podcast. In episode 115, we will be discussing the topic of Coywolves and how they relate to the AP Biology Curriculum.

Keenan: For this episode, we’ve brought in Alex Profit and Serena Russel to discuss the evolution of coywolves. So, to start us off: what exactly is a Coywolf?

Alex: Well, ‘Coywolf’ is actually just a nickname for what is known to the scientific community as an eastern coyote. Eastern coyotes are hybrids of coyotes, wolves and dogs, however they are still primarily coyotes and remain as coyotes rather than wolves.

Keenan: So you say that the Coywolves, or eastern coyotes are a mix of several different species. Do you know the genetic breakdown?

Serena: It’s difficult to say for certain since the coyotes’ genetic makeup varies by region and population, but according to a DNA analysis done by Evolutionary Biologist Javier Monzón, they are 64% coyote, 13% gray wolf, 13% eastern wolf, and 10% dog.

Keenan: Wow, that’s some genetic diversity. So how do these new hybrids differ from their pure coyote ancestors?

Alex: For one thing, they’re larger. Eastern Coyotes are 35-37% larger than their western counterparts. They also have larger and more powerful heads, their ears are more rounded like a wolf’s and they have wolf-like fur markings. There’s lots of variation within and between populations, but coywolves' features tend to match the midpoint between coyotes and wolves.

Keenan: Fascinating! So from what I understand, this interbreeding is a fairly recent development. What led to it?

Serena: This story started several hundred years ago with the arrival of Europeans in the Americas. When Europeans colonized the East Coast of America they started cutting down forests and hunting large prey in the region, which threatened the habitat and food source of local grey wolves. At the same time, western coyotes, which are adapted to more open terrain, were drawn east by the expansion of their preferred habitat via deforestation. With shrinking numbers of grey wolves and a new thriving population of coyotes in the region, it makes sense that the wolves soon turned to coyotes as mating partners.

Serena: From there, natural selection took over. With the right mix of coyote and wolf DNA, a new species was created that was the best of both worlds. These “coywolves,” as they are called, are larger than coyotes, but inherited the social nature of wolves, meaning they form packs to hunt, which allows them to hunt large animals like deer in addition to the small prey that coyotes usually feed on. On top of that, they possess the strong ability of coyotes to adapt to urban environments, and are comfortable in both open and forested environments.

Keenan: I can see why this mixing would be beneficial, but is it considered evolution, or just hybridization?

Serena: Both. Coywolves have certainly evolved, but they have done so through the process of hybridization. The Coywolf, or eastern coyote was created from a mix of different species, but has diverged enough from the parent species that many believe it should be treated a separate species, though no official decision has yet been made on this matter.

Keenan: So coywolves aren’t considered a separate species?

Serena: Not yet. Coywolves have only been around for a few hundred years and are still in the earlier stages of their development, but many believe that they deserve to be recognized as their own species and will be soon.

Keenan: From what you’ve said, I’m sure it won’t be long before scientists acknowledge them. So you’ve told us all about the specifics of coywolves, but how does their development link into the larger picture of evolution that we discuss in AP Bio?

Alex: Coywolves are, of course, only a very small part of evolutionary history. However, because their development is so recent they provide a good example of direct observation as proof of evolution, which is discussed in AP Bio Chapter 7.6.

Keenan: And how do they exemplify direct observation of evolution?

Serena: Because coywolves have come into existence over only the past few hundred years, we, as humans, can visibly see the evolution from their parent species, coyotes, wolves, and dogs, to the new species of coywolves. This provides firm, observable evidence that species do change over time and evolution is something that happens, and, one can easily infer, has in the past as well.

Keenan: That’s all the time we have for today. Thank you Alex and Serena for taking the time to speak with us, and to our audience, Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Facts for Thoughts

References:

The Genesis of âCoywolves:â A Story of Survival. (2015, December 9). Earthjustice. Retrieved October 13, 2021, from https://earthjustice.org/blog/2015-december/the-genesis-of-coywolves-a-story-of-survival

Humphrey, B. (2021, April 20). Coydog, Coywolf, or Coyote? The 5 Things You Need to Know About Eastern Canids. Outdoor Life. Retrieved October 14, 2021, from https://www.outdoorlife.com/story/hunting/eastern-coyote-facts/

Magazine, S. (2015, November 3). Coywolves are Taking Over Eastern North America. Smithsonian Magazine. Retrieved October 12, 2021, from https://www.smithsonianmag.com/smart-news/coywolves-are-taking-over-eastern-north-america-180957141/

N. (2019, February 9). What is a ‘Coywolf?’ Wolf Conservation Center. Retrieved October 13, 2021, from https://nywolf.org/2017/12/what-is-a-coywolf/

Spider, I., & Spider, I. (2014, December 23). Coywolf: A Modern Species. The Infinite Spider. Retrieved October 9, 2021, from https://infinitespider.com/coywolf-modern-species/

Way, J. G. (2016, May 12). Why the eastern coyote should be a separate species: the ‘coywolf.’ The Conversation. Retrieved October 13, 2021, from https://theconversation.com/why-the-eastern-coyote-should-be-a-separate-species-the-coywolf-59214

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Examples of Evolution: Butterflies and Parasites

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: Butterflies and Parasites

Anushka Agarwal, Olivia Lundquist, & Hana Hamid

Welcome to My AP Biology Thoughts podcast, our names are Anushka, Olivia, and Hana and we are your hosts for Unit 7: Examples of Evolution-Butterflies and parasites. In episode 114, we will be discussing Butterflies and parasites and how they relate to the AP Biology Curriculum.

Segment 1: Overview of Butterflies and Parasites

To start off, what is evolution? Evolution is the process by which different organisms develop from their ancestors to adapt to the environment they are living in. This idea was proposed by Charles Darwin to explain how species have the ability to evolve. We can look at the Blue Moon butterflies for examples and how they adapted to their environment to protect themselves from the killing parasite. The Blue Moon Butterfly, or Hypolimnas bolina, is an eggfly commonly found in New Zealand, Australia, New Guinea, Solomons, etc. The blue moon butterfly’s mating season is normally in the spring and summer. Their name is derived from the 2 bright circular patches on the backs of the males. Natural selection occurring between the butterflies and parasites is an example of evolution happening in real time. This is because scientists discovered that the bluemoon butterflies developed resistance in a span of 10 generations (which lasted a year).
Additionally, the peppered moth is a species of a night-flying moth which is most commonly found in the northern hemisphere in countries such as Europe, Asia, and North America. They are generally small moths (only 1.5-2.5 inches) and their eggs normally hatch during mid summer. While some moths are typically light in color, many have dark skins and normally have extra camouflage to protect them from their predators (which includes flycatchers, nuthatches, and European robin). We can see a difference in the colors of the peppered moth due to the Industrial Revolution marked an era of industrial change in Europe and the United States from 1760-1840, which affected not only economy but the environment as well.

Segment 2: Evidence that supports Evolution of Butterflies and Parasites

mutation
the changing of a structure of a gene that may result in a variant form → can have impact bc it has the potential of getting passed down that leads to evolution
mutation: males can survive the infection of parasite that kills male embryos
normally they cant(mutation allowed for them to live and complete term/live)
Natural selection (blue moon butterflies)
Since the parasites normally targeted male blue moon butterflies, their population was a staggering 1%. However, because these butterflies obtained immunity from the parasite, their population bounced back to 40% in less than a year!
natural selection
the process of adaptation of a species in order to survive. It is caused by environmental factors.
before industrial revolution: moths were white
2% were black
after industrial revolution: moths were black
5% were white
not eaten as frequently after revolution when dark bc they blended better with the environment
artificial bc the environment changed, causing the need to adapt, bc of humans and factories
How peppered moths can be considered natural selection
before industrial revolution: moths were white
2% were black
after industrial revolution: moths were black
5% were white
How did this happen( factories were being built during the industrial revolution and burning coal for fuel helped them run, resulting in a dark smoke to cover the area
Moths pass their color to the next generation ( a mutation in the DNA of a single moth caused the mutation to pass on to other moths)
Dark moths started to live in dark forests (aided them in camouflage from predators)

Segment 3: Connection to the Course

AP Biology has a strong focus on evolution because it is crucial to learn about the interconnectedness of all living things on Earth to understand the advances that have been made in biology. Discoveries could only be made once evolution was accepted as scientific fact because it explains how life on Earth is the same and also very different than it was millions of years ago. More specifically, understanding evolution helps us to predict the geno and phenotypes of future generations, and explain how diseases are passed down. Also, understanding random mutation in butterflies can help us identify how butterflies have changed and evolved to survive- evolution is not goal driven, mutation creates variation which then can be acted upon by natural selection. And although humans are not intentionally choosing traits in natural selection, they may be impacted by the changes to species as a result of natural selection that occur around them.

**We can talk about the difference between natural selection and artificial selection (ribecca was saying this in class)

Artificial selection is humans intentionally selecting for traits
Natural selection is where changes are made naturally whereas artificial selection is where changes are made when humans intervene.
In the case of the peppered moths, the industrial revolution wasn’t purposely trying to change the moth population and although it was humans causing the revolution, it was because of the environment that the peppered moths were changing in color and, therefore, natural selection was occurring.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Examples of Evolution: Antibiotic Resistance

Hopewell Valley Student Publications Network — Tue, 23 Nov 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 7 Natural Selection

EPISODE TITLE: Antibiotic Resistance

Welcome to My AP Biology Thoughts podcast, I am Emily Greenberg and I am Angelina Graf and we will be your hosts for “Unit 7 Heredity: Examples of Evolution-antibiotic resistance”. In episode 113, we will be discussing antibiotic resistance and how it relates to the AP Biology Curriculum.

Segment 1: Overview of antibiotic resistance

Antibiotics are drugs that fight infections that are caused by bacteria
Antibiotic resistance is when bacteria and germs build up resistance to the medications that are meant to kill them
Antibiotic resistant germs are often very difficult to treat and dangerous infections can emerge
A common misconception is that antibiotic resistance means that the body is resisting antibiotics, however it is actually the bacteria that is becoming resistant to antibiotics
Overuse of antibiotics is one of the main causes of antibiotic resistance

Segment 2: Evidence that supports antibiotic resistance

Antibiotics also kill good bacteria that help to protect the body from infection
Antibiotic resistant germs can spread throughout healthcare facilities, the environment, and other communities.
The action of an antibiotic is an environmental pressure
Species have to adapt and evolve in order to survive these pressures
We know that evolution is happening because bacterial infections can continue to spread even with the presence of antibiotics
Penicillin resistance:
In WWI, penicillin treatment was used to treat the wounded and by some smaller civilian populations
Biochemists began reporting resistance to it before the war was over and found a penicillin-inactivating enzyme secreted from a particular bacteria.
Over the next few decades, overuse and repeated exposure to antibiotics helped the selection and replication of antibiotic resistant strains of bacteria

Segment 3: Connection to the Course

Antibiotic resistance evolves as a result of natural selection and genetic mutation
Bacteria that develop mutations that are resistant to antibiotics are more likely to survive and reproduce; this means that they are more fit
If resistant bacteria reproduce with other resistant bacteria, their offspring will be fully resistant and this trait will become more frequent in the gene pool
Overall, antibiotic resistance is dangerous because bacteria can develop resistance to extremely high amounts of antibiotics in a short amount of time which would leave patients very difficult to treat

It’s crucial to understand Antibiotic resistance to ensure that harmful antibiotic resistant bacteria don’t evolve faster than our ability to treat them

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (Enter your closing Tag-line)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
YouTube
Connect with us on Social Media
Twitter @thehvspn

Chromosomal Inheritance

Hopewell Valley Student Publications Network — Thu, 17 Jun 2021 09:00:00 -0500

Welcome to My AP Biology Thoughts podcast, my name is Stefanie Ribecca and I am your host for episode # 104 called Unit 5 Heredity: Chromosomal Inheritance. Today we will be discussing how inheritance occurs in the chromosomal level.

Segment 1: Introduction to Chromosomal Inheritance

Chromosomal inheritance is an extension of Mendelian genetics.
Chromosomes contain DNA which carry the genetic information that code for proteins.
Chromosomes are found in pairs, and increase genetic variation during meiosis.

Segment 2: More About Chromosomal Inheritance

During meiosis, non sister chromatids in homologous pairs exchange information during crossing over.
Certain genes may be close together on the chromosome and may appear to be inherited together.

Segment 3: Connection to the Course

Chromosomal inheritance allows for a combination of traits from both parents.
Genetic diversity from chromosomal inheritance allows individuals in a population to adapt to the environment.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Biotechnology

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #112 called Unit 6 Gene Expression and Regulation: Biotechnology. Today we will be discussing how we use technology to study how the mechanisms of DNA and gene expression work.

Segment 1: Introduction to Biotechnology

The four main processes used in biotechnology that relate to this unit are bacteria transformation, PCR, electrophoresis, and DNA sequencing. Bacterial transformation makes multiple copies of a recombinant DNA molecule. PCR is used to produce millions of copies of a DNA sequence from an initial sample. Electrophoresis separates DNA and RNA molecules by their size and their electrical charge. DNA sequencing is used to determine the sequence of the bases in a DNA molecule.

Segment 2: More About Biotechnology

First we’ll talk about bacterial transformation. The process of bacterial transformation starts with mixing the prepared bacteria with DNA. Then the bacteria are heat shocked. This allows them to take up a plasmid. The bacteria that take up the plasmid become resistant to antibiotics, so we place all of the bacteria on an antibiotic plate. The ones that survive are the ones that are known to have taken up the plasmid since they survived the antibiotic. The bacteria without the plasmid end up dying. The bacteria that survived end up being used to create a cluster of identical bacteria that also contain the plasmid. The colony containing the plasmid is grown and used to produce the plasmid or proteins.
Another form of biotechnology is PCR. To begin, the main ingredients (taq polymerase, primers, template DNA, nucleotides, and cofactors) are all added in a tube. The first step of PCR is denaturation. In denaturation the reaction is heated so that the DNA strands separate and create single strands. The next step is annealing where the reaction is cooled so that the primers bind to the complementary sequence on the DNA strands. The third step is extension. In this step the temperature is raised again so that the taq polymerase starts at the primers and synthesizes new strands of DNA. This cycle repeats between 25-35 times which ends up creating millions of copies of the same DNA region.
Electrophoresis is another form of important bio technology. In electrophoresis, DNA samples are placed into indentations at one end of a gel. THis gel gets an electric current applied to it. Since DNA fragments are negatively charged, they move towards the positive electrode. Because the DNA fragments have the same charge, the smaller fragments are able to move through the gel faster than the large ones. This allows the DNA to be separated by size. The gel is then stained with a DNA binding dye which makes the DNA fragments appear as bands so that they can be observed.
The last thing we are going to talk about is DNA sequencing. In DNA sequencing, the DNA strand goes through bacterial transformation so that we can produce many copies of it in a plasmid. The DNA is then isolated and goes into a plate with other ingredients like the DNA bases, DNA polymerase, primers, and modified bases labeled with colored fluorescent tags called terminator bases. This mixture then goes through a process very similar to PCR. The difference is when polymerase adds the bases, it eventually adds a terminal base which makes it so that no more bases can be added to the strand of DNA. This then produces lots of fragments of DNA at different lengths. Then when we separate them by size through electrophoresis, we can figure out where the beginning of the sequence is. When the fragments are separated in the gel, a laser reads the terminator base of each strand which gives us the full sequence of bases

Segment 3: Connection to the Course

It’s important for us to know how these different processes work because it helps us understand how we apply the things we know about gene expression and regulation. The knowledge of gene expression and regulation allows scientists to create processes like PCR, electrophoresis, bacterial transformation, and DNA sequencing. For example scientists use what they know about DNA replication in order to replicate DNA at an exponential rate in a lab through PCR. These different processes help us in scientific research and in medicine.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Mutations

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Arthur Kim and I am your host for episode # 111 called Unit 6 Gene Expression and Regulation: Mutations. Today we will be discussing what genetic mutations are, the different types, as well as some of the possible effects.

Segment 1: Introduction to Mutations

A mutation is any change to a sequence of DNA.
They’re not always bad, as some mutations can arise that result in a more favorable phenotype.
Mutations can also occur on the scale of chromosomes, often as a result in errors in meiosis.

Segment 2: More About Mutations

On a strand of DNA, there are two main types of mutations that can occur.
Point mutations are the result of swapping one base pair for another.
Very often, these aren’t a big deal because only one amino acid will be affected or possibly unaffected since oftentimes more than one codon produces the same amino acid. In many cases, the protein that the mutated strand codes for will still be functional.
Frameshift mutations are the result of an insertion or deletion of a base pair in a strand of DNA.
These are often detrimental because they completely change the codons in an entire sequence of mRNA. As a result, the protein will be synthesized with completely different amino acids than what they’re supposed to be.
This causes the protein to be nonfunctional.
Frameshift mutations are the cause of several deadly genetic diseases such as Tay Sachs and cystic fibrosis.
At the level of chromosomes, the types of mutations that can occur are deletions (part of the chromosome is lost), duplications (an extra copy of a part of a chromosome), inversions (the orientation of a segment of a chromosome is flipped), and translocation (two chromosomes exchange components).

Segment 3: Connection to the Course

Genetic mutations are one of the main sources of variation within the gene pool. As a result, mutations are what allow for evolution to occur in populations, bringing about the diversity of life on Earth we see today.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Gene Expression & Cell Specialization

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Shriya Karthikvatsan and I am your host for episode #110 called Unit 6: Gene Expression and Regulation. Today we will be discussing the mechanisms used by cells to increase or decrease the production of specific gene types, and how this fits into the overarching unit.

Segment 1: Introduction to Gene Expression and Regulation

We will begin by going over a few helpful terms and ideas to provide context for the topic of gene expression and regulation which is a pretty broad topic as a whole
A gene consists of a string of DNA hidden in a cell’s nucleus, and what we will unpack is how it knows when to express itself and cause the production of a string of amino acids called a protein
The overall process is that a string of DNA is expressed to make RNA
Then, something called mRNA is translated from nucleic acid coding to protein coding to form a protein
In terms of regulation, genes can’t control an organism on their own so they must interact with and respond to the organism’s environment
Some genes are always “on” regardless of environmental conditions, and these genes are among the most important elements of the genome because they control the ability of DNA to replicate, express itself, repair itself, and perform protein synthesis
Overall, regulated genes are needed occasionally and get turned “on” or “off”
Regulation differs between prokaryotes and eukaryotes because in prokaryotes, most regulatory proteins are negative and turn genes off
In eukaryotes, cell-cell differences are determined by expression of different sets of genes
This means that an undifferentiated fertilized egg looks and acts quite different from a skin cell, a neuron, or a muscle cell because of differences in the genes each cell expresses
In the next segment we will go into further detail of the specific processes involved in expression and regulation

Segment 2: More About Gene Expression and Regulation

Gene expression begins with transcription which makes mRNA and the overall process is the same in both prokaryotes and eukaryotes
Prokaryotes lack a nuclear envelope, and eukaryotes use an extra step called RNA processing where RNA is edited and introns are edited out and exons are spliced together
It is catalyzed by RNA polymerase which separates DNA strands and links RNA nucleotides at the 3’ end (side notes: prokaryotes have 1 type of polymerase and eukaryotes have 3)
Transcription is initiated when RNA polymerase binds to a promoter and unwinds the DNA strands
Initiation site and a small sequence after are recognized by transcription factors which are proteins that bind to promoter and guide RNA polymerase to bind to TATA box
Then, mRNA carries the genetic code and mRNA itself is a series of codons
In eukaryotes, mRNA processing works by the 5’ end getting a GTP cap and the 3’ end getting a poly-A tail
Also, a splicesome complex of SnRNPs + a protein work together to cut out the introns (intruding codons) and splice the exons (expressed codons) together
Following transcription, translation occurs in the ribosome after mRNA brings the genetic code and it is when tRNA brings the amino acid and the ribosome is able to be completely assembled
Translation is initiated by a small subunit of the ribosome which binds to a recognition site on the mRNA and an anticodon of tRNA initiator binds to a start codon
The next part of translation is elongation in which the anticodon of the next tRNA binds to a codon at the A site and the polypeptide bonds the 2nd amino acid onto the 1st amino acid (this process repeats until a stop codon is reached)
Finally, termination is when the stop codon reaches the A site and a release factor frees the tRNA from the P site and disconnects the polypeptide causing everything to separate
After translation, the protein is modified in ways such as:
The amino acid can be cut off, the protein folds, or sugars and lipids are added
Mutations can also occur which are changes in DNA sequences or the genome
Gene regulation involves:
Promoters are nucleotide sequences where RNA polymerase binds to initiate transcription
Operons are a cluster of related genes with a common metabolic pathway that are controlled together by a “master switch”
An operator is a DNA sequence to which the repressor binds
Regulatory gene—codes for a repressor protein
Repressor—protein that binds to the operator and blocks RNA polymerase
Corepressor—small molecule that binds to the repressor
The two types of operons are:
Tryptophan operon—codes for production of tryptophan (amino acid) and it is repressible meaning the pathway product switches the operon off
Lac operon—codes for proteins needed for take up and metabolism of lactose and it is inducible, meaning the pathway is switched on by the nutrient it uses

Segment 3: Connection to the Course

Overall, gene expression and regulation is so significant because genes encode for proteins and dictate cell function
The thousands of genes expressed in a particular cell determine what that cell can do which allows for life processes to occur and be able to help an organism
It also creates variation which allows for differences in the expression of genes that accounts for phenotypic differences between organisms
The regulation of gene expression conserves energy and space
It would require a significant amount of energy for an organism to express every gene at all times, so it is more energy efficient to turn on the genes only when they are required

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Regulation of Gene Expression

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Helena Holley and I am your host for episode #109 called Unit 6 gene expression and regulation: Regulation of gene expression. Today we will be discussing the mechanism of gene expressions and regulation in Eukaryotes and Prokaryotes.

Segment 1: Introduction to Gene Expression and Regulation

Gene expression and its regulation and control is essential for cell specialization in Eukaryotes. All cells have the same information, however their differences in function come from which genes they express. As you go through development cells are differentiated. The way this happens is by specific transcription factors and translation controls that tell the cells which genes they are expressing as you develop. Your basic genetics are not the only thing that determines which genes are expressed, epigenetics also plays a role. Certain environmental factors that occur in a parents lifetime can alter the gene expression of offspring. This happens when there are changes in the parents' cells that undergo meiosis to produce gametes. Examples of this include DNA methylation and histone modification. While I was just discussing eukaryotes above, gene expression and regulation is also important in prokaryotes, which I will discuss more later.

Segment 2: More About Gene Expression and Regulation

There are various ways in which gene expression is regulated in Eukaryotes. One regulation method is determined by how tightly DNA is wrapped around Histone proteins. The tighter the DNA is wrapped, the harder it is for transcription to take place, and certain enzymes can alter how tight or loose it is wrapped depending on what needs to happen. There are also chromatin-modifying enzymes that can make the DNA more or less accessible. Another regulatory factor is the Control elements which are regulatory sequences on DNA that control the expression of proteins. Alternative RNA splicing helps to regulate post transcription, as it produces different mRNA from the same gene. Another useful method is mRNA degradation which is used to break down mRNA if the protein is not needed to be expressed anymore. Finally, various regulatory proteins can block initiation of translation if that is needed. It is important to note that mRNA is not the only type of RNA used for regulation, and there are various types of non-coding RNA that have different functions in regulation of gene expression. In prokaryotes there are repressible and inducible operons. The repressible operon genes are able to be silenced, and the inducible operon genes are able to be turned on. This function of these operons is important in gene regulation because if a repressible operon is absent, the repressor is inactive and the operon will be produced. When too much of a repressible operon is in the cell, it will bind to the repressor which will bind to the operator, preventing any more from being produced. For inducible operons, the process works essentially the opposite of the repressible operons (so briefly the repressor is active when there is an absence of lac operon, and it is inactive when there is presence lac operon).

Segment 3: Connection to the Course

Gene expression and regulation is important because any errors in regulation can lead to developmental problems. For example, If the tumor suppressor gene is silenced due DNA methylation occurring in the parent, the offspring would be very susceptible to cancer and disease. Another reason why the regulation of expression of genes is important is because not having all genes turned on all the time, conserves a lot of energy and space. It is a lot more efficient to only turn on genes when they are required. Additionally, if every gene was being expressed, cells would have to be much larger because DNA has to be unwound in order to transcribe and translate it.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (for your children's sake, maybe don't go explore the radiation danger zone)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Translation

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Saarim Rizavi and I am your host for episode #108 called Unit 6 Gene Expression and Regulation: Translation. Today we will be discussing everything there is to know about translation. I will first be giving a brief overview of what translation is, it’s overall function, the 3 steps involved in translation, and some of the different components and organelles involved in translation. I’ll then go into greater detail on the individual steps of translation which will involve the organelles and different components mentioned before. Finally, I will relate the process of translation to the broader topic of gene expression and regulation. Before I begin, I would like to give credit to Khan Academy, biologydictionary.com, and nature.com for the information they provided me with in order for this podcast to be possible. So thanks to them. Alright, so here we go:

Segment 1: Introduction to Translation

Translation is the process of creating proteins from an mRNA template
A cell reads information from mRNA molecules and uses this information to build a protein - involves decoding an mRNA and using its information to build a polypeptide, and multiple polypeptide chains form a protein
Three basic steps of translation - initiation, elongation, and termination
Initiation - the ribosomes get together with the mRNA and the first tRNA so translation can begin
Elongation - the amino acids are brought to the ribosome by tRNAs and linked together to form a chain of amino acids
Termination - the finished polypeptide is released to go and do its job in the cell
In mRNA, the instructions for building a polypeptide come in groups of 3 nucleotides called codons - there are 61 codons for amino acids and each of them is read to specify a certain amino acid out of the 20 possible amino acids
Stop codons tell the cell when polypeptide is complete and the AUG codon is the start codon which signals the start of protein construction
In translation, the codons of an mRNA are read in order, from the 5’ end to the 3’ end, by tRNAs.
tRNA’s = molecular bridges that connect mRNA codons to the amino acid they encode
One end of the tRNA has a sequence of 3 nucleotides called an anticodon, which binds to a matching mRNA codon through base pairing; the other end of the tRNA carries the amino acid specified by the codons
tRNAs bind to mRNAs inside the ribosomes - ribosomes are made up of protein and ribosomal RNA
The ribosomes provide a set of slots where tRNAs can find their matching codons on the mRNA template and deliver their amino acids. As these tRNAs enter slots in the ribosome and bind to codons, their amino acids are linked to the growing polypeptide chain in a chemical reaction.

Segment 2: More About Translation

Initiation
Ribosome, an mRNA with instructions for the protein to be built, and an initiator tRNA carrying the first amino acid in the protein - these components come together to form the initiation complex which is the molecular setup needed to make a new protein
The tRNA carrying the methionine attaches to the small ribosomal subunit - they bind to the 5’ end of the mRNA by recognizing the 5’ GTP cap which was added during processing in the nucleus
They go along the mRNA in the 3’ direction, stopping when they reach the start codon (eukaryotic cells)
In bacteria, the small ribosomal subunit attaches directly to certain sequences in the mRNA - these Shine-Dalgarno sequences mark the start of each coding sequence, letting the ribosome find the right start codon for each gene.
Elongation
The amino acid chain gets longer and the mRNA is read one codon at a time, and the amino acid matching each codon is added to a growing protein chain
Detailed:
The first methionine- carrying tRNA (methionine is an amino acid specified by the start codon, AUG) starts out in the middle slot of the ribosome, called the P site.
A fresh codon is exposed in another slot, called the A site. The A site will be the landing site of the next tRNA whose anticodon would be complementary to the exposed codon
Once the matching tRNA has landed in the A site, the formation of the peptide bond that connects one amino acid to another occurs
A methionine from the first tRNA in transfered onto the amino acid of the second tRNA in the A site
The mRNA is pulled onward through the ribosome by one codon after peptide bond formed - this shift allows the first, empty tRNA to drift out via the E or exit site. It also exposes a new codon in the A site, so the cycle can repeat itself.
Summary:
When a new codon is exposed, a matching, complementary tRNA binds to the codon, the existing polypeptide is linked onto the amino acid of the tRNA, and the mRNA is shifted one codon over in the ribosome which allows a new exposed codon to be read and the cycle continues.
Termination
The finished polypeptide chain is released
A stop codon in the mRNA enters the A site
Stop codons are recognized by release factors, which fit into the P site
Release factors mess up the enzyme that normally forms peptide bonds by making the enzyme add a water molecule to the last amino acid of the chain
This reaction separates the chain from the tRNA, and the newly made protein is released out of the ribosome.
Processing
Editing the polypeptides so that they are ready to then perform their correct function in the cell.
The new polypeptide will fold into a distinct 3D structure, and may join with other polypeptides to make a multi-part protein
Amino acids may be chemically altered or removed
Some proteins contain special amino acid sequences that direct them to certain parts of the cell - through protein targeting, the proteins reach their destination.

Segment 3: Connection to Gene Expression & Regulation

A DNA molecule is divided up into functional units called genes - each gene provides instructions for a functional product, or a molecule needed to perform a job in the cell (polypeptide molecule)
Genes provide instructions for building polypeptides which fold up and combine to make complex proteins
Transcription - the process in which the DNA sequence of a gene is copied to make an RNA molecule
If the gene that is transcribed encodes a protein, the RNA molecule will be read to make a protein in translation (when the sequence of the mRNA is decoded to specify the amino acid sequence of a polypeptide)
Central dogma - transcription + translation = process of info going from DNA to RNA to protein

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. ((Learning new things doesn’t have to be challenging. It’s really easy once you have a goal in mind and a purpose for everything you do)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Transcription & RNA Processing

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Chloe McGregor and I am your host for episode #107 called Unit 6 Gene Expression and Regulation: transcription and RNA processing. Today we will be discussing the process of transcription, and how MRNA is processed on its way to the ribosomes.

Segment 1: Introduction to Transcription and RNA Processing

The central dogma is the process by which the genetic information stored in DNA is converted into functional products such as proteins. This process consists of 3 steps: transcription, translation, and protein synthesis. In this episode, I will specifically discuss transcription, the process of transcribing shorter segments of DNA into mRNA strands. However, once these mRNA strands are created, there are still steps that take place to ensure that the strand is mature and ready to be translated. This is called RNA processing. The mRNA strand is manipulated into a mature strand through a series of processes, and is then ready to travel to the ribosomes for translation and protein synthesis.

Segment 2: More About Transcription and RNA Processing

As I mentioned earlier, transcription is the first step and this is when the DNA strand is read, and a new complementary mRNA strand is synthesized. DNA is composed of different nitrogenous bases compared to RNA. DNA consists of adenine, thymine, cytosine, and guanine. However, RNA contains uracil instead of thymine. Base pairing rules are used by RNA polymerase to synthesize a new strand using the information on the unzipped DNA strand. Transcription is very important because DNA is very unique and one of a kind, so this single strand of RNA makes it possible for the genetic information to stay safe, but also be used for protein synthesis outside of the nucleus. Following transcription, RNA processing occurs. Premature mRNA strands contain both introns and exons that are transcribed from the DNA, however, the introns are spliced out to create a concise and mature strand of RNA that is ready to be translated. Introns are removed to ensure that the correct protein is being created during protein synthesis because a mistake in the RNA strand can cause mistakes during translation. Also, if introns are kept on accident, the wrong protein can be produced which will disrupt many different cellular processes. RNA splicing is also the reasoning behind one strand of DNA coding for so many different proteins depending on which introns are spliced out, and which exons are kept in the sequence.

Segment 3: Connection to the Course

Transcription and RNA processing play a major role in healthy cellular function and bodily function in general. Because specific proteins and enzymes are so vital to so many different processes that are happening simultaneously, it is important that transcription and RNA processing are happening precisely and efficiently to keep the body functioning. The idea of RNA processing is also important because it can provide different proteins from the same gene depending on what the body is in need of. Overall, these processes may seem small, but they play such a large role in kickstarting protein synthesis and making sure that the RNA strands are accurate and ready to be converted into proteins.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

DNA Replication

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode # 106 called Unit 6 Gene Expression and Regulation: DNA Replication. Today we will be discussing the process by which cells replicate their DNA

Segment 1: Introduction to DNA Replication

Difference between prokaryotic and Eukaryotic DNA
P is one circular piece of dna where eukaryotic are multiple linear chromosomes
DNA replication is semi-conservative
Double helix is split in two and then each new strand is synthesized so to new double helices are made, each with one old and one new strand
very complex but very fast
Extremely accurate (only 1 in a billion bases are messed up)
Have to prime the DNA for replication
Primers are short molecules that attach to the dna at the origin of replication
Mde by the enzyme primase
Helicase is the enzyme that unwinds the double helix- initiates the replication fork (where two strands split apart)
Multiple replication forks in eukaryotic dna
Topoisomerase checks problems in the DNA before replication and maintains the structure
DNA polymerase is the enzyme that synthesizes the new DNA strand- reads the bases and matches up complementary nucleotides

Segment 2: More About the process of replication

Replication initiation can occur at both directions from the origin where the primer binds
DNA polymerase can only add nucleotides in the 5 to 3 prime direction, and read the strand of dna in the 3 to 5 prime direction
Leading strand is continuous
Lagging strand is discontinuous, has to read and synthesize in short segments (okazaki fragments)
Enzyme ligase seals together the fragments
Energy needed for this process (remember forming bonds between the nucleotides requires energy)

Segment 3: Connection to the Course

Connection to mitosis
S phase of mitosis is dna replication
Necessary for cell division to make the same amount of chromosomes in daughter cells
Process is close to the same for rna synthesis
Leading and lagging strands
Okazaki fragments and 3 to 5 prime direction vs 5 to 3 prime direction

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

DNA & RNA Structure

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 6 Gene Expression and Regulation

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline Sun and I am your host for episode #105 called Unit 6 Gene Expression and Regulation: DNA and RNA Structure. Today we will be discussing the central structural components of DNA and RNA as well as the similarities and differences between the two.

Segment 1: Introduction to DNA and RNA Structure

Deoxyribonucleic acid, DNA, and ribonucleic acid, RNA, are two of the most important biological molecules for survival
DNA responsible for carrying genetic information is commonly considered the “blueprint” for life’s functions. Its basal structure, a double helix that is unique from RNA, is key to its ability to replicate itself. DNA, when not undergoing replication, is coiled up into compact structures known as chromosomes. They are wrapped around histone proteins: the degree of tightness to which they are wrapped determines how much of the DNA is expressed.
RNA builds off of DNA and creates a template from which proteins can be created in ribosomes. Because they are based off of a parent DNA strand, RNA has a single strand instead of two.

Segment 2: More About DNA and RNA Structure

However, there is much more to DNA and RNA Structure than the helical strands.

Lets first focus on what makes up the strands for DNA and RNA:

Both DNA and RNA have a sugar-phosphate backbone that is key to holding the entire molecule together.
However, the sugar in DNA is deoxyribose sugar, from which it derives its name. The sugar in RNA is ribose sugar, which has one more hydroxyl group than the sugar in DNA.
The sugar and phosphate group in DNA and RNA alternate repeatedly. They link with a special directionality that is often denoted with a 5’ and 3’ end. This is a rather abstract concept, but basically the 5’ and 3’ indicate which carbon in a sugar molecule the phosphate group will attach itself, forming the repeating phosphate-sugar backbone.
Another central structural component are the nitrogenous bases found in both DNA and RNA, with one key difference.
DNA has the bases adenine, cytosine, guanine, and thymine. Adenine and guanine are known as purine bases, while cytosine and thymine are the pyrimidine bases. Purines tend to be larger than pyrimidines because purines have a double ring structure as opposed to pyrimidine’s single ring structure.
Only purines and pyrimidines can bind together. Specifically, in DNA, adenine and thymine bind together, while cytosine and guanine bond together. They are held together by hydrogen bonds which link not only the bases, but also the two strands of DNA to form a double helix. The 1:1 ratio by which the nitrogenous bases bond (adenine=thymine, guanin=cytosine) explains how DNA molecules are able to replicate by synthesizing a new strand from a parent strand.
RNA has the same bases of adenine, cytosine, and guanine, but the key difference is that it has uracil instead of thymine. Its purines are still adenine and guanine, but it's pyrimidines are cytosine and uracil. Adenine will match with uracil as opposed to thymine in RNA synthesis.
Lengthwise, DNA tends to be significantly longer than RNA.
This is because while RNA is based on DNA, it will not code for the entire strand but only a certain segment of a strand. As a result, an RNA strand may only be a few thousand base pairs long, while DNA can reach from hundreds of thousands to millions of pairs long.
There are also coding and non coding regions of DNA that are transcribed into RNA. The coding regions of DNA known as genes are the ones that can serve as templates for the synthesis of proteins, while the non coding regions have no role in creating proteins. However, non coding regions are still important. They provide structural support to the DNA molecules and also may act as regulators for gene expression.
When DNA is transcribed in RNA, the coding regions become known as exons in RNA, and the noncoding regions become known as introns. In a process known as splicing, RNA will undergo modifications that cut out the non coding introns and bind together the remaining coding exons. After this, the RNA molecule is ready to be translated into proteins.
Another key structural component of DNA that are actually made up of proteins and RNA subunits are telomeres. Telomeres are repetitive sequences of non-coding DNA that act as a protective cap for DNA strands. They prevent strands from fraying or splitting at the ends, but telomeres will shorten every time DNA replicates, which is often associated with the deterioration of life.

Segment 3: Connection to the Course

Understanding the structure of DNA and RNA is important to understanding how both function as some of the most important macromolecules in life. For example, the unwindable double helix structure and the complementary base-pairing rules explain why DNA can replicate semi-conservatively, which is vital to our continued survival and our production of viable offspring. It is also important to understand the structural differences between DNA and RNA. These distinctions define the different capabilities of both molecules: DNA is the universal genetic code, and RNA is responsible for transcribing that code into templates used to create proteins. Faults in the structure of either DNA and RNA can potentially have disastrous ramifications on the health and function of an organism, so understanding the structure is the first step towards maximizing survival.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Environmental Effect on Phenotype

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Nikki Evich and I am your host for episode #103 called Unit 5 Heredity Environmental Effect on Phenotype. Today we will be discussing how the environment can alter phenotypes.

Segment 1: Introduction to Environmental Effect on Phenotype

Phenotype is determined by genotype
Genotype and environment work together to determine phenotype
temperature, oxygen levels, humidity, light cycles, and the presence of mutagens can all impact which of an animal's genes are expressed, which ultimately affects the animal's phenotype
These can turn on and off genes

Segment 2: More About Environmental Effect on Phenotype

Fur color
These rabbits and cats have a mutant allele for the coat color gene that is white
The enzyme encoded by the gene is inactive at temperatures above about 35 degrees
The extremities are cooler than the main body (around 25 degrees), so the fur on these regions is dark.

Segment 3: Connection to the Course

Environmental pressures drive diversity in ecosystems
Phenotypic diversity is caused by not only genetics, but the environment as well
A higher diversity in ecosystems allows populations to be better suited for sudden changes to their ecosystem

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Bye now!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Incomplete Dominance, Codominance, and Multiple Alleles

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode #102 called Unit 5 Heredity: Different expressions of alleles. Today we will be discussing incomplete dominance, codominance and multiple alleles.

Segment 1: Introduction to expression of alleles

Alleles are what make us unique, they code us and make us appear the way we are. In simple biology, we learn about how genotype affects phenotype and when we start off on this concept, we visualize a simple set of alleles. And when we first start to learn about alleles, we learn that dominant alleles override and affect the phenotype even if a recessive allele is present. Let’s use ear lobes as an example; we can say attached earlobes are recessive and loose are dominant. If the offspring has attached earlobes and both parents have unattached earlobes, we see a perfect example of simple inheritance. We would typically draw out a punnett square. We cannot directly see what’s the genotype of the parents, however we can assume that they are both heterozygous due to the nature that their offspring is homozygous recessive. When drawing out the Punnett square, we can see that there is a 50/50 chance that the offspring will have attached earlobes.

Segment 2: More About this

However, nothing is ever that simple. As you can see, in the world around us, there are more than just two outcomes when it comes to anything living. In most cases, there are many more than just 2 phenotypes. The world is much more complicated than just dominant and recessive. That's where incomplete dominance, codominance and multiple alleles come into play. They show us that there is much more to life than just capital and lowercase letters.To start off, incomplete dominance has the same number of alleles as a standard dominant and recessive genotype. The main difference is that heterozygous organisms no longer just express the dominant allele, they express a phenotype that is in between homozygous dominant and homozygous recessive. A great example of this is some sort of flower. If there are three colors of flower, one red, one white and one pink. The red can be determined as the “dominant” while the white could be “recessive”, making any flower with heterozygous alleles pink. This represents incomplete dominance. And just like incomplete dominance, codominance is only made up of a single set of alleles too. However, instead of the phenotype being somewhere in the middle, for codominance, the phenotype for heterozygous is a mix of the two. Meaning if a species is represented by the genotype of one dominant and one recessive, they are going to express both phenotypes, in their own respective way. Now for when alleles get complicated. When there are multiple alleles, the same rules apply for simple dominance, where the heterozygous only expresses the dominant phenotype. However, there are more alleles that influence the phenotype as well. Depending on the trait, there could be 4 or more alleles that determine what a species looks like. Just like in eye color, where there are 16 different genes that determine what colors your eyes could be. And in theory you could use a Punnett square to determine the predicted offspring phenotypes, but that square would be substantially larger and more complicated as different letters are flying around.

Segment 3: Connection to the Course

All in all, a variety of things can influence how a species can look. And the different expression of alleles can alter those looks even more. But that’s all there for a cause. All of these alleles got there somehow, whether it be natural selection or a random mutation that had the benefit of the doubt. But these alleles can show us whether a recessive trait is more fit for one environment than another. All of this has a purpose, everything happens for a reason, and looking at alleles we can now predict what the outcomes could be.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. SEEYA!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Linked Genes

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Victoria Villagran and I am your host for episode #101 called Unit 5 Heredity: Linked Genes. Today we will be discussing linked genes and their characteristics!

Segment 1: Introduction to Linked Genes

Linked Genes
A form of non-mendelian inheritance
Discovered by Thomas Hunt Morgan, using the fruit fly Drosophila melanogaster
Genes on the same chromosome, making them more likely to be inherited together
If crossing over occurs, then they are no longer linked it will look like independent assortment
If they are linked, they will not assort independently and the ratios of the offspring will different
If there are more parental phenotypes, then it is linked
If there are more recombinant then is it non-linked
The recombination frequency is very small. If the genes are far apart on a chromosome, or on different chromosomes, the recombination frequency is 50%. ... If the recombination frequency is less than 50% we say the two loci are linked
Recombinant and Map Units:
The farther apart the genes are on the chromosome, the more likely they are to separate because of crossing over resulting in recombinant offspring
Recombinant offspring generally appear in proportions related to the recombination frequency between the two genes:
Calculated by dividing the number of recombinant progeny by the total number of progeny
This can be used to calculate map units or how far away the genes are from each other

Segment 2: More About Linked Genes

Let’s look at fruit flies
If linkage held true, then F1 would only have the two parental phenotypes in a 1:1 ratio
The genes for eye color and the genes for wing length are on the same chromosome, thus are inherited together.
A cross between gray and normal with black vestigial
There are more parental phenotypes with 965 and 944 than recombinant with 206 for gray and vestigial, and 185 with black normal. There is an expected 575 frequency for each genotype
they are linked, so they did not assort independently and the ratios of actual offspring were different from the expected

Segment 3: Connection to Heredity

Linked genes and heredity, specific non-mendelian inheritance are connected
Heredity or inheritance is the passing on of traits or genetic information from one generation to the the next, and linked genes are a specific way how these genes are passed on from being on the same chromosome and not independently assorted, giving more parental phenotypes. For example, the farther apart the genes are on the chromosome, the more likely they are to separate because of crossing over resulting in recombinant offspring. The location and space between genes dictate the way they will be inherited by new generations.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Have a nice day!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

X-Linked Inheritance & Polygenic Inheritance

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode #100 called Unit 5 Heredity: X-Linked Inheritance & Polygenic Inheritance. Today we will be discussing how X-linked inheritance and polygenic inheritance work.

Segment 1: Introduction to X-Linked Inheritance & Polygenic Inheritance

X-linked and polygenic are both different types of non-mendelian inheritance. Mendelian inheritance follows the laws of segregation and independent assortment, so X-linked and polygenic traits by definition do not follow these laws.
X-linked traits are traits whose alleles are carried on the sex chromosomes instead of the normal chromosomes. Males have XY sex chromosomes, and females have XX sex chromosomes. In x-linked inheritance, the allele for a trait is only carried on the x chromosome. This means that any male who inherits the allele will express the trait since he only has one copy of the x chromosome. X-linked traits can be dominant or recessive, just like in mendelian inheritance. However, since the alleles are located on the x chromosome, any male who gets the linked allele will express the trait. In females, x-linked inheritance works like mendelian inheritance - if both x chromosomes have the recessive allele, it is expressed, otherwise the dominant allele will always be expressed.
Polygenic inheritance is when a single phenotypic trait is controlled by multiple genes. This is different from multiple alleles because in polygenic inheritance, all of the polygenic genes can be found in an individual, while in multiple alleles, only two of the alleles are present in an individual. Polygenic inheritance also produces a range of phenotypes, rather than specific distinct phenotypes. Polygenic inheritance also doesn’t exhibit complete dominance, which is why there is a range of phenotypes.

Segment 2: More About X-Linked Inheritance & Polygenic Inheritance

One example of an x-linked trait is hemophilia. In males who possess the altered copy of the gene, they will always express the phenotype for hemophilia because they only have one copy of the X chromosome. However women need two copies of the altered gene to express the phenotype. This is because hemophilia is an x-linked RECESSIVE trait. If it was x-linked dominant, the woman would only need one copy of the altered gene to express the phenotype.
Polygenic inheritance includes traits like hair color, height, and skin color, as well as non visible traits like blood pressure and intelligence. Skin color is one example of this. Skin color is controlled by the pigment melanin, and darker skin results from more melanin. Hypothetically, the production of melanin is controlled by contributing alleles which will be called A, B, and C, which results in dark skin color. The non contributing alleles lowercase a, b, and c, produce a light skin color. Since polygenic alleles don’t display dominance, each contributing allele gives an additive effect in which the different alleles create a spectrum of possible phenotypes. In this example, individuals with all uppercase alleles will have the darkest skin, and individuals with all lowercase alleles will have the lightest skin color.

Segment 3: Connection to the Course

X-linked and polygenic inheritance are very common. Although most people only learn about Mendelian inheritance, x-linked and polygenic traits are still prevalent and control many prominent phenotypic traits, such as hair and skin color, as well as susceptibility to diseases.
X-linked and polygenic traits prove that mendelian inheritance isn’t the most important pattern of inheritance, even if it may be the most commonly known. Because x-linked traits often determine an individual’s susceptibility to diseases, they are extremely important to understand. Additionally because polygenic inheritance is easily seen in people’s skin and hair color, it is important to understand this pattern of inheritance as well.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time on My AP Biology Thoughts Podcast!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Mendelian Genetics

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Adrienne Li and I am your host for episode #99 called Unit 5 Heredity: Mendelian Genetics. Today we will be discussing Mendel’s experiment with pea plants, and the three laws he proposed from his results.

Segment 1: Introduction to Mendelian Genetics

First off, lets define what mendelian genetics is. It’s a concept about heredity that was formed by Gregor Mendel and states that genes are distinct units that come in pairs and are inherited independently from other genes. These make up an offspring’s genome and provide the basis of inheritance for sexual reproduction. Now, Mendel didn’t just come up with this concept randomly. It started with an experiment he conducted where he crossbred pure pea plants with different traits such as purple vs. white flowers and tall vs. short stems. The F1 generation all carried the same trait as one of the parents, which refuted the prior notion that inheritance was a blend of the parent’s traits since the flowers weren’t pink. What was more strange was the F2 generation, which had a 3:1 ratio where 3 individuals had the same trait as one parent and 1 individual had the other parent’s trait.

Segment 2: More About Mendelian Genetics

From these experimental results, Mendel summarized his findings in 3 laws. The first one is the law of dominance where genes have two alleles, and the dominant allele will conceal the recessive allele. This was seen in the F1 generation where all the flowers were purple even though one of the parents had white flowers. This meant that purple was dominant while white was recessive, thus only the purple flower trait was expressed. The F2 generation with a 3:1 ratio further confirmed this concept because breeding heterozygotes results in 4 offspring, one that is homozygous dominant, two that are heterozygous, and one that is homozygous recessive which means 3 individuals will express the dominant trait and one will express the recessive trait. Next, the second law is the law of independent assortment which states that alleles of two or more different genes are sorted into gametes independently of another where the allele a gamete receives for one gene does not influence the allele receive for another. This idea was demonstrated when he performed dihybrid crosses which tested two different traits and it resulted in a 9:3:3:1 ratio. This showed that traits such as flower color and stem length are inherited independently from each other, and one does not influence how the other trait is inherited. Lastly, the law of segregation says that during reproduction, the gametes only receive one copy of a gene from each parent at random. This was demonstrated by his 3:1 ratio where during segregation in meiosis of the F1 generation, each gamete acquired one of the two genes so that there were three possible combinations, either homozygous dominant, heterozygous, or homozygous recessive. Since there were two ways to form heterozygotes, either receiving one dominant and one recessive allele from either parent, and because heterozygotes and homozygous dominant gametes express the same phenotype, it supported the 3:1 ratio and law of segregation.

Segment 3: Connection to the Course

Tying this back to the overall ideas in Unit 5, mendelian genetics corroborates the concept of genotypes, phenotypes, and punnett squares. Genotypes are the pairs of alleles that an individual has, such as one purple flower and one white flower allele, whereas phenotypes are the expressed traits which in this example would be a purple flower. This makes sense because of mendelian genetics and the law of dominance, where the dominant allele which is purple flowers, conceals the recessive white flower allele. As for punnett squares, the reason why we can use them to predict mendelian inheritance patterns is because of the law of segregation and independent assortment. The law of segregation allows us to give each gamete one allele from each parent so we can draw an allele in each of the four boxes, and the law of independent assortment allows us to draw alleles independently of one another in dihybrid punnett square crosses since the alleles of one trait are inherited separately from another trait. So that about sums mendelian genetics.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time bio buddies!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Meiosis and Genetic Diversity

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Pauline Brillouet and I am your host for episode #98 called Unit 5 Heredity: Meiosis and Genetic Diversity. Today we will be discussing how the process of meiosis promotes genetic diversity

Segment 1: Introduction to Meiosis and Genetic Diversity

Let's do a quick overview of the stages of meiosis.
The cell must first go through interphase for cell growth, development, and DNA replication. Then, it proceeds to meiosis I where chromosomes condense, the nuclear envelope breaks down, and a synapsis occurs. This synapsis in prophase I involves homologous chromosomes forming a tetrad to line up and cross over at the chiasmata.
The homologous pairs are then split up by the spindles, but sister chromatids remain attached at the centromere. Finally, meiosis II is the exact same process as mitosis except that DNA is not replicated so interphase is shorter. The key component of meiosis II is that now sister chromatids are pulled apart to make four haploid cells.
The purpose of meiosis is to make haploid cells from a diploid cell. It is essential for sexual reproduction in eukaryotes because it produces gametes to be used in fertilization. There are new combinations of genetic material in each of the four gamete cells.

Segment 2: More About Meiosis and Genetic Diversity

Now let’s explain where genetic diversity comes into play. First, the synapsis in prophase I results in genetic variation because pairs swap genetic information with one another, making recombinant chromosomes. Since the exchange of chromosome segments occurs between non sister chromatids, crossing over creates new combinations of genes in the gametes that are not found in either parent, contributing to genetic diversity.
Next, the law of independent assortment explains increased genetic variation. It states that the alleles of two or more different genes get sorted into gametes independently of one another during anaphase I of meiosis. In other words, the allele a gamete receives for one gene does not influence that allele received for another gene. This allows for 2n number of possible chromosome combinations where n is the haploid number of the organism
Lastly, random fertilization extenuates the amount of diploid combinations infinitely. 1 sperm cell has 1 in 8,000,000 possible chromosome combinations, which fuses with an egg cell that also has 1 in 8,000,000 possible chromosome combinations. So there are a total of 64 trillion possible combinations.

Segment 3: Connection to the Course

As new combinations of gene variants are made, they can make the organism more or less fit or able to survive and reproduce. This ties into natural selection favoring the better adapted organisms
Genetic diversity is important because it helps maintain the health of a population, by including alleles that may be valuable in resisting diseases and other stresses. Maintaining diversity gives the population a buffer against change, providing the flexibility to adapt.
Extinction risk has been associated with low genetic diversity and several researchers have documented reduced fitness in populations with low genetic diversity.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Thank you!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Meiosis

Hopewell Valley Student Publications Network — Wed, 02 Jun 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 5 Heredity

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode # 97 called Unit 5 Heredity: Meiosis. Today we will be discussing what meiosis is, why it's important, and how it connects to other topics we’ve learned about this year.

Segment 1: Introduction to why Meiosis is important

From what we have learned this year, we know Mitosis is used to prudence daughter cells that are genetically identical to a parent cell. On the other hand, the function of meiosis is to produce gametes. The daughter cells have half as many chromosomes as the parent. To put it in other words, a diploid cell is the parent to 4 haploid cells. In humans, the haploid cells produced are sperm and egg cells, essential for reproduction to occur. It imporant that meiosis occurs to produce sex cells and not mitosis because the combiation of 2 cells both with the nomral number of chromosomes during fertiliztion would result in an offspring wth double the normal number of chromosomes. Meiosis also created 4 unique haploid cells unlike mitosis which creates identical daughter cells. Meiosis creates new combinations of genetic material in each of the four daughter cells. The gametes produced through meiosis exhibit a larger range of genetic variation and this allows for genetic variation in a population. This genetic variation is increased even more when the two gametes unite during sexual reproduction. This overall helps to increase diversity in a population which increases the chances of the population surviving in a changing environment. Another difference between Meiosis and Mitosis is that Meiosis involves two rounds of nuclear division. The other events of Meiosis are pretty similar to Mitosis but there are some key differences.

Segment 2: More About what meiosis is

To begin, a cell will first go through interphase where the cell grows during the G_1 phase, replicates its DNA during the S phase, and prepares for division during the G_2 phase. Then the cell enters Meiosis 1. It begins in prophase 1 where the chromosomes begin to condense. Unlike mitosis, the condensed chromosomes begin to pair up with their homologous partner. The DNA is then broken at the same spot on each chromosome and the homologous chromosomes exchange part of their DNA in a process called crossing over. This process of crossing over increases genetic variation producing unique chromosomes. After crossing over, the spindle fibers capture the chromosomes and move them towards the center of the cell. THis is similar to how the chromosomes in mitosis are moved by spindle fibers, but in meiosis, homologous pairs—not individual chromosomes—line up at the metaphase plate for separation. The orientation of each pair is random and this allows for the formation of gametes with different sets of chromosomes. In anaphase I, the homologues are pulled apart and move apart to opposite ends of the cell. The sister chromatids of each chromosome, however, remain attached to one another and don't come apart. Finally, in telophase I, the chromosomes arrive at opposite poles of the cell and cytokinesis occurs separating the two haploid daughter cells. After meiosis one, the cell does not re enter interphase to grow like it did before meiosis 1. The daughter cells produced by meiosis 1 enter meiosis 2. These cells are haploid but their chromosomes still consist of two sister chromatids. In meiosis II, the sister chromatids separate, making haploid cells with non-duplicated chromosomes. As part of prophase II, chromosomes condense and the nuclear envelope, if it was present, breaks down. The spindle forms between the speratedd centrosomes, and the spindle microtubules begin to capture chromosomes. The two sister chromatids of each chromosome are captured by fibers from opposite spindle poles. In metaphase II, the chromosomes line up individually along the metaphase plate. In anaphase II, the sister chromatids separate and are pulled towards opposite poles of the cell. In telophase II, nuclear membranes form around each set of chromosomes, and the chromosomes decondense. Cytokinesis splits the chromosome sets into new cells, forming the final four haploid cells in which each chromosome has just one chromatid.

Segment 3: Connection to the Course

Meiosis can connect to natural selection concepts studied earlier in the year. Meiosis increases genetic diversity through crossing over. This can cause the allele of the offspring to be different from those of the parent and the population. Variation allows some individuals within a population to adapt to the changing environment. Some new alleles increase an organism’s ability to survive and reproduce, which then ensures the survival of the allele in the population. Other new alleles may be immediately fatal and organisms carrying these new mutations will die out.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. !

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Regulation of Cell Cycle

Hopewell Valley Student Publications Network — Thu, 27 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Alex Jing and I am your host for episode #96 called Unit 4 Cell Communication and Cell Cycle: Regulation of Cell Cycle. Today we will be discussing How cells regulate their division

Segment 1: Introduction to Cell Cycle Regulation

The cell cycle includes 4 main stages: G1, S, G2, and mitosis. These phases are responsible for the division of cells. However, how do the cells determine when they can proceed to the next stage of the cell cycle?
Cells regulate their advancement in the cell cycle through the use of Cyclin-dependent kinases, or CDKs, and CDK inhibitors. When CDKs are active, they phosphorylate other enzymes in the cell responsible for activating the next stage of the cell cycle. CDK inhibitors are receptors that when activated, will inhibit the CDKs, preventing the cell from going to the next stage.

Segment 2: More About the Regulation of the Cell Cycle

A prominent example of why CDKs and their inhibitors are so important is the development of cancer. Cancers form when cells are growing at an rapid, unrestricted rate, and are usually caused by some mutations in the cell which results in either overactive CDKs or inactive CDK inhibitors. P53 is a CDK inhibitor which is responsible for ensuring that DNA is not damaged during the replication process. If it detects damaged DNA it will send out signals to inhibit the CDKs. If a mutation caused the P53 to not be responsive, than cells could be able to divide with damaged DNA, leading to a new cancer to form.

Segment 3: Connection to the Course

Regulation of the cell cycle is an essential part of all living organisms. Being able to conduct mitosis is what allows organisms to grow and replace damaged cells, and being able to regulate this process is extremely important to ensuring that division is done correctly.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

CDK and Cyclins

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode #95 called Unit 4 Cell Communication and Cell Cycle: CDK and Cyclins. Today we will be discussing what cyclins and CDK are and why they're important.

Segment 1: Introduction to CDK and Cyclins

Cyclins are a group of related proteins, and there are four basic types found in humans and most other eukaryotes. These include G1cyclins, G1/S cyclins, S cyclins, and M cyclins. Each cyclin is associated with a particular phase, transition, or set of phases in the cell cycle and helps drive the events of that phase or period. For instance, M cyclin promotes the events of the Mitosis phase, such as nuclear envelope breakdown and chromosome condensation. Cyclin-dependent kinases, or CDKs, are enzymes that catalyze the phosphorylation of target proteins in the cell cycle. The attached phosphate makes the target protein more or less active. The CDKs are activated when attached to cyclin because the cyclin changes the shape of the enzyme. When a cyclin attaches to a Cdk, it has two important effects: it activates the Cdk as a kinase, but it also directs the Cdk to a specific set of target proteins ensuring that those are proteins appropriate to the cell cycle period controlled by the cyclin. After the phosphorylation of proteins is complete, cyclin breaks down and CDK is inactive. CDK-Cyclins also act as a control or regulator for the cell cycle. Cdk activity and target proteins change as levels of the various cyclins rise and fall. In addition to needing a cyclin, Cdks must also be phosphorylated on a particular site in order to be active.

Segment 2: More About CDK and Cyclins

An example of how cyclins and cdks work is the mitosis-promoting factor. A MPF molecule is a CDK bound to an M cyclin. As the cell approaches the G2/ Mitosis transition phase in the cycle, the levels of the M cyclin increase. It then binds to CDKs present in the cell and together they cause the Mitosis phase to begin. The MDF adds phosphate to protein in the nuclear envelope, causing it to break down, and activates chromosome condensation promoting targets. In addition to driving the events of M phase, MPF also triggers its own destruction by activating the anaphase-promoting complex/cyclosome or APC/C, a protein complex that causes M cyclins to be destroyed starting in anaphase. The destruction of M cyclins pushes the cell out of mitosis, allowing the new daughter cells to enter G1.
CDKs and cyclins often respond to cues from the cell to regulate. Positive cues, like growth factors, increase activity of Cdks and cyclins, while negative ones, like DNA damage, usually decrease activity. When DNA damage occurs, a protein called p53 triggers the production of CDK inhibitor proteins. These proteins bind to Cdk-cyclin complexes and block their activity, allowing time for DNA repair to occur. By ensuring that cells don't divide when their DNA is damaged, mutations are not being passed onto daughter cells. When p53 is defective or missing, mutations can accumulate, potentially leading to cancer

Segment 3: Connection to the Course

Cylins and CDK can connect to the principles of evolution. Cyclins and Cdks are found in many different types of species, from yeast to frogs to humans. They vary slightly in each organism. For example, yeast has just one Cdk, while humans and other mammals have multiple Cdks that are used at different stages of the cell cycle. These common enzymes and proteins can provide evidence of a common ancestor between these species.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Mitosis

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode #94 called Unit 4 Cell Communication: Mitosis. Today we will be discussing the steps in mitosis and its connection to the cell cycle and regulatory processes.

Segment 1: Introduction to Mitosis

Before we get into the steps of mitosis, lets first define what it is. Mitosis is the division of a cell nucleus to form 2 identical daughter cells. Some important words to know so we can understand this process include chromosome, which consists of 2 identical halves called sister chromatids and are attached by centromere, sister chromatids, which are a single, tightly coiled molecule of DNA, chromatin, which is condensed DNA that coils around protein, and spindle fibers, which attach to the sister chromatids of the centromeres and pull apart the chromosomes.

Segment 2: More About Mitosis

So now that you know those definitions, let's dive into the steps of mitosis which include prophase, metaphase, anaphase, and telophase. In order for mitosis to begin, each chromosome must have two chromatids that were previously formed during S phase of interphase. In prophase, many processes occur including the chromosomes condensing in order to protect the DNA, the centrosomes moving to opposite poles, the nuclear envelope breaking down, and the microtubules connecting to the centromeres. Next is metaphase where the chromosomes line up on the metaphase plate, which is the plane between the two poles of the spindle. Then, the microtubules pull each chromosome apart into two chromatids. The significance of this step is that it ensures that all DNA chromatids separate when the cell cycle is functioning normally. Then, anaphase occurs where the microtubules shorten and pull the chromosomes to opposite poles so each pole has a complete set of chromosomes that have the same number as the original cell. Lastly, mitosis ends with telophase where it reverses the processes from prophase. The previously broken down nuclear envelope and nucleus begin to reform, the chromatin decondenses, and the DNA unwinds from the histone protein. Specifically in animal cells, a groove forms called the cleavage furrow as the purse strings are tightened and the cell splits into two. At the conclusion of mitosis, two daughter cells are formed, each with two identical copies of every chromosome but each chromosome only has one chromatid.

Segment 3: Connection to the Course

To connect mitosis back to the bigger ideas of cell communication and regulation in unit 4, let’s take a look at how mitosis occurs. One way cells control division is through cyclin-dependent kinases which are enzymes that advance cells past checkpoints. They phosphorylate target proteins in the cell cycle and when activated, they attach to cyclins which change the shape of the enzyme. This sends chemical signals which either turn on or off cell division. For example, mitosis-promoting factor is a cyclin-CDK complex that moves cells through the G2 checkpoint. Since G2 is the phase leading up to mitosis, MPF aids mitosis because it allows the cell to synthesize the nutrients necessary for mitosis to successfully form two normal daughter cells. This demonstrates the relationship between mitosis and cell regulation and division where cell regulatory mechanisms move cells through the cell cycle which eventually initiate mitosis.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time bio buddies!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Cell Cycle

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Chloe McGregor and I am your host for episode #93 called Unit 4 Cell Communication and Cell Cycle: The Cell Cycle. Today we will be discussing the basics of the cell cycle including how it works and what products are made.

Segment 1: Introduction to the Cell Cycle

The cell cycle is split up into 2 different parts, each with their own purpose. The first part of the cell cycle is called interphase. The cell spends a majority of its time in this phase. Interphase itself is made up of 3 different stages. These stages are the G1, S, and G2 phase. The first step in interphase is G1. During this step, the cell spends its time growing in size and gaining a sufficient amount of resources. With this abundance of resources, the cell is able to replicate its DNA and intracellular components during the S phase. The third step is G2 where the cell continues its growth and will stop its progression to the mitotic phase if there are any issues or damaged DNA. The second part of the cell cycle is the mitotic phase which has 2 parts. The first part is mitosis. Mitosis consists of four steps: Prophase, metaphase, anaphase, and telophase. More details about these steps will be discussed later in the episode, but generally they work together in order to separate the replicated DNA. The second part of the mitotic phase is cytokinesis where the cell actually splits into 2 new identical daughter cells. Overall, each step in the cell cycle is important to grow the cell and its resources in order to produce 2 identical daughter cells, each with the same copies of DNA. Another important part of the cell cycle is the G0 phase. Although this isn’t the generic path of cell replication , a cell may enter the G0 phase if there is a non sufficient amount of resources and nutrients available to proceed to healthy replication. Cells may also enter G0 if they are adult cells that are not necessarily looking to replicate. For example, a lot of cells in your brain and nervous system stop replicating once you reach adulthood, so an injury in these areas could be extremely difficult, or impossible, to heal.

Segment 2: More About the Cell Cycle

To go more in depth, let’s talk about the different steps in mitosis. Once again, these steps are prophase, metaphase, anaphase, and telophase. The goal of mitosis is to separate the replicated DNA on opposite sides of the cell, with both sides having identical copies of the DNA. Prophase begins once G2 is finished and the cell has grown enough. In prophase, the DNA condenses, and the replicated chromosomes have a more visible shape to them. The replicated chromosomes are called sister chromatids and are linked together at a point called the centromere. The next step, metaphase, is when the replicated chromosomes line up in the center of the cell in a line. Anaphase is next, and this is where the spindle fibers on each side of the cell attach to the centromere region on each sister chromatid. Then, the fibers pull the sister chromatids apart, leaving opposite sides of the cell with identical genetic material. Telophase is the last stage of mitosis where each side of the cell begins to form a nuclear envelope around the new genetic material. The chromosomes also unravel back into chromatin. Once mitosis is complete, the cell membrane scrunches in the middle of the cell causing it to physically separate into two identical daughter cells. This step is called cytokinesis. Another important point to touch on is the checkpoints that occur during the cell cycle. Although there is a separate episode on cell cycle regulation, it is important to understand that the cell reaches checkpoints throughout the entire cell cycle which ensure that it is healthy, and that the DNA is replicating correctly. There are 3 checkpoints. These are near the end of G1, between G2 and the M phase, and one during metaphase. These checkpoints are extremely important to ensure that the products of the cell cycle are two completely identical and healthy daughter cells.

Segment 3: Connection to the Course

An important connection to the course is the idea of mutations, and how they occur during the cell cycle. A mutation is a change in the structure of a gene caused by a mistake or alteration in the base units of the DNA. Because mutations involve DNA, they can occur during S phase or mitosis when the DNA is being replicated and split into two new cells. Mutations can be silent, beneficial, or detrimental to an organism which plays a big role in evolution. As random mutations occur during the cell cycle, organisms can evolve and natural selection can occur causing only the most fit organism to survive and reproduce. Overall, the cell cycle is extremely important to the growth and survival of organisms around the world, and includes many intricate steps and phases to make sure it is done correctly and efficiently.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Feedback Loops

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode 92 called Unit 4 Cell Communication and Cell Cycle: Feedback loops. Today we will be discussing how organisms maintain homeostasis

Segment 1: Introduction to Feedback loops

There are 2 types of feedback loops found in the systems of our bodies. The first is negative and the second is positive. These feedback loops are ways for our body to determine whether the cells are healthy or sickly. These feedback loops typically occur when the product or output of an event or reaction changes the organism's response to that reaction. So typically, the cells in our body do not want anything to change, they have to have optimal temperature, pH, concentration, everything. The process of regulating these happen during feedback loops and different stimuli and reactions occur to perform this. Looking at the different types of feedback loops, we can see that both try to maintain homeostasis. They both have an overarching goal of consistency and equilibrium.

Segment 2: More About Feedback loops

Negative feedback loops are typically the most popular and common example of feedback loops. This is when a stimulus disrupts a receptor. This receptor then in turn puts out various tasks to help alleviate the stimulus until it is all gone. A great example of this is the thermostat in a house. The stimulus is the temperature getting too cold. This negative feedback in turn activates the thermostat which turns on the heat. And until the temperature in the room matches the temperature on the thermostat, the heat continues to warm up the room. Now for the opposite; a positive feedback loop. This is just a series of different reactions that cycles until a big event occurs at the end of it. The best way to look at these different types of feedback loops is to look at the graphs that represent them. On the X-axis is time while the y-axis is stimulus. The cell wants to be at 0, which means homeostasis. Now for negative feedback loops, we see that the line starts at 0 but then an event occurs that throws off the balance. Either going up or down, the cell corrects it and heads towards 0, however it overshoots and continues the pattern of a sine graph until its amplitude slowly reaches 0. Positive feedback loops are a bit different. In terms that the graph slowly goes up and up until it reaches the even and then plummets back to 0. These graphs help us visualize the process and the final goal of each loop.

Segment 3: Connection to the Course

This all plays into the theme of systems in biology. Systems in our bodies run all around the clock to maintain homeostasis and to keep us healthy and strong. These feedback loops are necessary to tell the cell whether something is wrong or right, and this is what causes these loops. It is important to know this because these types of activities ties into everyday things. Just like thermostats and pregnancies. It is important to know and understand these things so we know when something goes wrong. It’s also important to note that our bodies are functioning the right way and it’s constant need to keep us healthy.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Changes to Signal Transduction Pathways

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Helena Holley and I am your host for episode #91 called Unit 4 Cell Communication and Cell Cycle: Changes in signal transduction pathways. Today we will be discussing factors that affect signal transduction pathways and their consequences in the body.

Segment 1: Introduction to Changes in signal transduction pathways

The first thing to know is what are signal transduction pathways? This is a process in which extracellular ligands/signaling molecules bind to receptors, which could be located inside the cell or on it’s surface, and triggers a series of events which results in a cellular response or multiple responses. Depending on the pathway this process could involve the use of a secondary messenger. This is typically an intracellular signaling molecule that amplifies the signal inside the cell in response to the presence of an extracellular signaling molecule in order to reach the target cell that will initiate cellular response. The signal transduction pathways can alter a lot of cell functions and that is why it is critical that all parts of the process function correctly. Changes in parts of the process can cause disorders and disease.

Segment 2: More About changes in signaling transduction pathways

The signaling transduction pathway is a complicated process that requires a lot of factors to work properly in order to reach the desired response, and because this process is so complicated there are a lot of chances for something to go wrong. First of all, mutations in signaling molecules could cause it to be unable to bind to the receptor and therefore the whole signaling transduction pathway will not be able to occur. This same situation can happen if the receptor was mutated, hence the signaling molecule won't be able to bind to the receptor. The next place where something in the pathway could be altered is during transduction. If one of the relay molecules is mutated this could stop the process from finishing or it could result in a different (potentially harmful) response to the initial signal. Certain chemicals can also affect signaling transduction pathways by either activated or deactivating a process and change the cellular response that happens.

Segment 3: Connection to the Course

Alteration in signaling transduction pathways can lead to diseases such as type 1 diabetes or cancers. This is why it is important to understand how the steps in the pathway works and where things can go awry. If we can understand where the issue is taking place that causes cancer or causes diabetes, we can help the individual by disrupting the cancer signaling pathway or giving the patient insulin. The signaling transduction pathway is used in the body all the time, whether it be during the cell cycle or after we eat some glucose and that's why it is crucial to understand the mechanisms by which it works so we can combat issues that may arise during it.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Eat a cookie you gotta make sure those insulin receptors still work from time to time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Cellular Responses in Signaling Pathways

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Victoria Villagran and I am your host for episode #90 called Unit 4 Cell Communication and Cell Cycle: Cellular Responses in Signaling Pathways. Today we will be discussing general cellular responses in signaling pathways.

Segment 1: Introduction to Cellular Responses in Signaling Pathways

Signaling pathway:
Signaling begins with the recognition of a chemical messenger, a ligand, by a receptor protein in a target cell
The ligand-binding domain of a receptor recognizes a specific chemical messenger, which can be a peptide, a small chemical, or protein, in a specific one-to-one relationship
Signal reception, which is when the target cell receives a signaling molecule; transduction, which is a series of events that converts the signal to something the target cell can respond to; and cellular response, which is when the target cell responds to the signal.
They are many varieties of ligands and receptors, and them binding can lead to many different responses
May involved 2nd messengers or phosphorylation, and protein phosphorylation
They all produce some kind of cellular response
The same signal or ligand can lead to different responses
Signal Pathways may influence how the cell responds to its environment
Responses can be short or long term
We can see changes such as an increase in the transcription of certain genes or the activity of particular enzymes.
We may be able to see changes in the outward behavior or appearance of the cell, such as cell growth or cell death, that are caused by the molecular changes
Three Response Types
1. Metabolism/Growth/Enzyme Activation/Open Ion Channel
Altering the activity of specific enzymes, metabolic enzymes in the cell become more or less active
Activated G Protein binds to a molecule that starts the transduction pathway, we will go into more detail later
Some signals bind to ligand-gated ion channels which either open or close in response to binding
2. Gene Expression
The process where information from a gene is used by the cell to produce a functional product, a protein. It involves two steps, transcription and translation.
Signaling pathways can target either or both steps to alter the amount of a particular protein produced in a cell.
Intracellular receptor: ligands are small or non-polar and can diffuse into the membrane. They are an activated hormone-receptor that can act as a transcription factor and affect gene expression
Controlling which genes are expressed or not through a number control mechanisms
3. Apoptosis: programmed cell death in cell cycle (also T cell Recognition)
Internal signals (such as those triggered by damaged DNA) can lead to apoptosis, but so can signals from outside the cell.

Segment 2: More About Specific Cellular Responses

Metabolism: Epinephrine
When epinephrine binds to its receptor on a muscle cell (G protein-coupled receptor), it triggers a signal transduction cascade involving production of the second messenger molecule cyclic AMP (cAMP). This cascade leads to phosphorylation of two metabolic enzymes, causing a change in the enzymes' behavior.
The first enzyme is glycogen phosphorylase (GP) which breaks down glycogen into glucose. Phosphorylation activates glycogen phosphorylase, causing lots of glucose to be released.
The second enzyme that gets phosphorylated is glycogen synthase (GS) and it is involved in building up glycogen, and phosphorylation inhibits its activity.
Through regulation of these enzymes, a muscle cell rapidly gets a large, ready pool of glucose molecules. The glucose is available for use by the muscle cell in response to a sudden surge of adrenaline aka the “fight or flight” response.
Apoptosis: External Signaling
Most animal cells have receptors that interact with the extracellular matrix, a structural supportive network of proteins and carbohydrates.
The binding of cellular receptors to the extracellular matrix initiates a signaling cascade within the cell.
If the cell moves away from the extracellular matrix, the signaling ceases, and the cell undergoes apoptosis. This keeps cells from traveling through the body and proliferating out of control.

Segment 3: Connection to Cell Communication and Cell Cycle

Understanding the different types of cellular response in signaling pathways is key to learning cell communication and the cell cycle.
These responses are a result of a signal from the cell or other cells to carry out a process to achieve either cell death, growth, or to express a certain gene. In other words, the response is how we can see cells communicating because it is the goal of all signaling pathways.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Have a nice day!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Transduction Secondary Receptors

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode #89 called Unit 4 Cell Communication and Cell Cycle: transduction; secondary receptors. Today we will be discussing secondary receptors and their role in the signal transduction

Segment 1: Introduction to transduction pathways

In signal transduction, there are three things that are necessary for the cell to do.

First, the signal, or ligand, must bind to the receptor, either on the cell's surface or inside the membrane. This is the first component, which is known as reception.
From there, the transduction occurs, where proteins are activated, and it is the component that includes secondary messengers.
Lastly, the transduction pathway eventually elicits a response from the cell, which is the overall goal of cell signaling. This response can be anything from activating an enzyme to initiating apoptosis, which is programmed cell death.

After the ligand binds to its receptor and changes the shape, the cell sets off with a series of signaling events, all designed to amplify the signal and eventually reach a response. This chain of events is what we call the transduction pathway. The first way transduction occurs is through protein phosphorylation, where a series of proteins are activated by phosphorylases. The other way transduction can occur is by secondary messengers, so let's learn more about those!

Segment 2: More About secondary messengers

Secondary messengers are small molecules that are specifically not proteins, although proteins play a huge role in the cell cycle. These secondary messengers are the ones that receive the signal from the first ligand when it binds to its receptor. The signal, or ligand, is thought of as the first messenger, so these little molecules that pick up and carry along the signal are therefore secondary messengers. Two examples of secondary messengers are calcium ions and cyclic AMP.

First, calcium in the form of Ca2+ ions are a very common secondary messenger in cells. They are stored in the endoplasmic reticulum, which is purposeful so they are isolated from the rest of the cell until they are needed and released. The pathway starts with a signal that binds to and opens one of the ligand-gated calcium ion channels in the cell. With an open ion channel, calcium ions from the extracellular space are able to flow freely into the cell and greatly increase the concentration of Ca2+ ions in the cytoplasm. From there, the abundance of calcium ions bind with various proteins in the cell, changing their shape and function to initiate a response. Secondary messengers are nonspecific, so the signals can lead to many types of responses based on the proteins present and type of cell.

The next example of a secondary messenger is cyclic AMP. Cyclic AMP is made when an enzyme gets a specific signal and converts ATP into the new molecule of cyclic AMP, also referred to as cAMP. Once it is made from the ATP, cAMP activates protein kinase A, a molecule that phosphorylates other proteins and passes along the signal to produce different responses.

Segment 3: Connection to the Course

Secondary messengers have many connections to this unit of cell communication and the cell cycle, as well as the overall biology course. To start, it is important to understand signal transduction pathways and the three components before diving deeper into secondary messengers. We must know the purpose of these signaling pathways, as well as how they are started and what happens, which would be our three components of reception, transduction, and response.

Additionally, we know that the purpose of secondary messengers is to amplify a signal and achieve a response, which we can see physically by responses in our body. For example, one of the secondary messengers we talked about earlier was calcium, which has a specific signaling pathway in beta cells of the pancreas. A signal of high blood glucose levels hits the cell and is amplified by the secondary messenger Ca2+ which triggers the release of insulin to be released into the bloodstream. Another example of a physical response to cell signaling would come from secondary messenger calcium ions in muscle cells, which elicit the response of muscle contraction.

Lastly, secondary messengers used in signaling pathways can be present in the cell cycle itself. If there is damaged DNA, a signal might be sent to fix it, or if the problem persists the cell might initiate apoptosis. These signals can be received by secondary messengers and passed along to initiate the needed response. On the other hand, if the cell is going through the cycle without problems, the signal sent might be to activate a CDK and push the cell into the next phase, another example of a signal that can be amplified and carried on by secondary messengers.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Transduction: Phosphorylation Cascades

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode #88. This is Unit 4 Cell Communication and Cell Cycle and today, we will be talking about transduction phosphorylation cascades

Segment 1: Introduction to transduction: phosphorylation cascades

Transduction is the second step in cell signaling pathways. It comes after reception, where the signal (which is called the ligand) is received by the receptor.
In order for the signal to start a response in the protein, the receptor needs to be activated. For the cell to produce a response, the next proteins in the chain also need to be activated. These proteins can be activated and deactivated like an on/off switch.
One of the ways that the signaling molecules are activated is phosphorylation. For a molecule to be phosphorylated, phosphate is added to the molecule. Phosphate groups are typically linked to either tyrosine, threonine, or serine, since these amino acids have hydroxyl groups in their side chains.
Phosphorylation is what can activate or deactivate the signaling molecules. It can also make the proteins more active (like an enzyme) or cause it to be broken down. Additionally, phosphorylation generally isn’t permanent. To de-phosphorylate a protein, cells have enzymes called phosphatases that remove the phosphate groups from the phosphorylated protein.
A phosphorylation cascade is when multiple signaling molecules in the cell signaling chain are phosphorylated, which transports the signal to another molecule to produce the end result.

Segment 2: examples of transduction: phosphorylation cascades

In order to better understand phosphorylation cascades, let’s look at an example.
One example of a phosphorylation cascade is the epidermal growth factor (EGF) pathway.
When growth factor ligands bind to the receptors, the receptors act as kinases and attach phosphate groups to each other’s intracellular tails. These receptors are now activated, triggering a series of events. Since these events don’t include phosphorylation, we won’t cover them in detail and will instead talk about the parts after that series that do involve phosphorylation.
Those events activate kinase Raf. This activated Raf phosphorylates and activates MEK, which in turn phosphorylates and activates ERKs. The ERKs then phosphorylate and activate other target molecules that then promote cell growth and division.
This specific pathway is called a mitogen-activated protein kinase cascade.
Because this specific pathway used multiple phosphorylation events that triggered other phosphorylations, it can be classified as a phosphorylation cascade.

Segment 3: Connection to the Course

Phosphorylation cascades are extremely important in cell signaling pathways because they allow the cell to respond to more than one cell signal. Phosphorylation cascades trigger multiple cellular responses, because the phosphorylation of one protein leads to the phosphorylation of another.
Additionally, if phosphorylation cascades become out of control, especially cascades that signal for growth factor, cancer can occur. This shows that being able to stop cell signaling is extremely important, since if cell growth and division goes unregulated, it becomes dangerous.
To stop cell growth and division, the cell may receive a signal to undergo apoptosis, or cell death. This usually happens if a cell doesn’t pass a checkpoint in the cell cycle, which is explained in further detail in another episode.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-run podcasts and digital content, make sure that you visit www.hvspn.com. See you next time on My AP Biology thoughts Podcast!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Reception: Ligand Gated Ion Channels and Intracellular Receptors

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Pauline Brillouet and I am your host for episode #87 called Unit 4 Cell Communication and Cell Cycle: Reception: Ligand Gated Ion Channels and Intracellular Receptors. Today we will be discussing the function and examples of these two types of receptors.

Segment 1: Introduction to Reception: Ligand Gated Ion Channels and Intracellular Receptors

Ligand gated ion channels and intracellular receptors are both involved in the first step of a signaling pathway known as reception. Reception is the process where a signal, or otherwise called a ligand, binds to a receptor. The ligand-binding domain of the receptor recognizes the specific chemical messenger to then start transduction. One thing to note is that the binding of ligand and receptor is noncovalent, so it is temporary and functions like an enzyme-substrate complex where size and shape of the signal is essential.
The main difference between the two receptors we are exploring is their location. Ligand-gated ion channels are membrane proteins. Meaning they are embedded in the membrane. Like the name suggests, intracellular receptors obviously lie within the cell.

Segment 2: More About Reception: Ligand Gated Ion Channels and Intracellular Receptors

Ligand gated ion channels either open or close in response to binding. They conduct ion flow. An example is a neurotransmitter binding to neurons, which opens the gate for Na+
Intracellular receptors require ligands that are small or nonpolar because they can diffuse through the membrane. An example of this is the sex hormone estrogen or any steroid hormone. When a hormone enters a cell and binds to its receptor, it causes the receptor to change shape, allowing the receptor-hormone complex to enter the nucleus (if it wasn’t there already) and regulate gene activity

Segment 3: Connection to the Course

The hydrophilic ion channel lets ions cross the membrane without having to touch the hydrophobic core of the phospholipid bilayer. Changes in ion levels inside the cell can change the activity of other molecules, such as ion-binding enzymes. The binding of neurotransmitters to neurons is also essential for the entire nervous system and basic brain functions such as attention, learning, and memory.
Intracellular receptors are unique because they cause these changes very directly, binding to the DNA and altering transcription themselves. A very important gas that acts as a ligand that is able to directly diffuse through the membrane is Nitric oxide (NO). It activates a signaling pathway in the smooth muscle surrounding blood vessels, one that makes the muscle relax and allows the blood vessels to expand. Drugs that treat heart diseases release NO to bind to the intracellular receptors and dilate vessels to restore blood flow to the heart.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Thank you!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Reception: G Protein Receptors, Tyrosine Kinase Receptors

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #86 called Unit 4 Cell Communication and Cell Cycle: G Protein Receptors and Tyrosine Kinase Receptors.

Segment 1: Introduction to G protein receptors and tyrosine kinase receptors

G Protein receptors and tyrosine kinase receptors both work to mediate cell communication by binding a signaling molecule, which is also called a ligand. Then this signal is sent through a transduction pathway where the last target protein causes some response. The response for both can be a variety of things such as gene expression, apoptosis, metabolic responses, cell division, or cell growth. Despite being similar in this way, g protein receptors and tyrosine kinase receptors work in very different ways

Segment 2: More About G protein receptors

Let's start by discussing g protein receptors. G proteins are very diverse and can bind to many different signals. One example is odorant (or scent) receptors. G proteins receptors are located in the cell membrane which is where an extracellular ligand binds to it. The signal is eventually sent to a g protein which is located on the membrane, but on the cytoplasmic side. Before the G protein is activated, GDP is bound to it which keeps it inactive. GDP is guanosine diphosphate. After the signal binds to the receptor, the receptor slightly changes shape and becomes active. Then, the GDP binds to the g protein receptor. Since the G protein no longer has a GDP bound to it, it frees it up to accept and bind to GTP. The GTP activates the G protein. The G protein is made up of three subunits: alpha, beta, and gamma. When the GTP is bound to the G protein and activates it, the alpha subunit detaches and moves away from the receptor. Now the G protein is split into two parts: one part is the single alpha subunit and the other is the beta and gamma subunits. These two parts can go on to interact with other proteins and cause a transduction pathway that results in one of many responses. Eventually, the alpha subunit comes back and hydrolyzes the GTP which keeps the G protein active and changes it back into GDP. At this point the G protein will once again become inactive. G proteins coupled receptors are very important in the human body. Disruptions can cause diseases like cystic fibrosis or cholera.
Now let's talk about tyrosine kinase receptors. Tyrosine kinase receptors are enzyme linked receptors. Enzyme linked receptors are receptors that are associated with an enzyme. A kinase is a protein that phosphorylates other proteins. For tyrosine kinase receptors, the kinase phosphorylates tyrosine. To start the process, a signalling molecule attaches to two tyrosine kinase receptors. These come together and form a dimer. Then, each tyrosine kinase receptor phosphorylates the domains of the tyrosine kinase receptor. Then, once the tyrosine is phosphorylated, it can send signals to other molecules

Segment 3: Connection to the Course

G protein receptors and tyrosine kinase receptors are very important to many species. Problems with g protein receptors can cause choler, cystic fibrosis, and some bacterial infections. Problems with tyrosine kinase receptors can also cause diseases and cancers. Both of these receptors play integral parts in many different species. This can be evidence of the endosymbiotic theory. Since so many species use these receptors, they likely came from a common ancestor and had an evolutionary advantage.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Immune System

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline Sun and I am your host for episode 85 called Unit 4 Cell Communication and Cell Cycle: The Immune System. Today we will be discussing how your body defends itself against infection and stays healthy through the complex yet vital immune system.

Segment 1: Introduction to The Immune System

The immune system is responsible for fighting off germs and other harmful outside invaders from entering and wreaking havoc on your body
Different from all other systems in that it is not a specific cell, tissue, or organ but is rather composed of several different cells, tissues, and organs working in tandem.
There are many important components of the immune system that can be divided into two general categories: the innate (or the non specific defense system), and the adaptive (or the specific defense system).

Segment 2: More About The Immune System

Innate (Nonspecific defense system). As the name suggests, you are born with it and it is automatically activated in the face of threats.

Uses physical and chemical barriers, killer cells, and fevers to defend the body
Simple Physical Barrier is the first aspect of the innate immune system
The skin is the first line of defense. It covers nearly every part of your outside body and acts as a physical barrier and keeps out many harmful microorganisms. As long as the skin is mostly undamaged or unharmed, its defense will hold.
Mucous membranes also provide a physical barrier. They line the body cavities that connect the inside of your body to the outside, such as the respiratory and urinary system. The thick viscosity of the mucus aids in preventing the entry of harmful microorganisms.
Both of these physical barriers also provide chemical defense. For example, The skin and stomach can secrete acids to kill off invaders. Sweat, which is also secreted by the skin, has antimicrobial proteins to kill bacteria. Enzymes can be found in mucus that perform the same function.
So lets say your skin was scraped up. Now your body relies on the second line of internal innate defense.
Your body may instigate a fever, send out chemical signals calling for defense from body parts, or cause inflammation. These are just a few of the main tactics the body may use, there are many more.

SO HOW DOES YOUR BODY DETECT WHERE THE INJURY IS AND WHERE TO DEFEND ITSELF. IT uses the...

Inflammatory response: A bodily process that uses chemicals to signal to the immune system defenders where the damage to the body is.
Utilizes redness, swelling, heat, and pain as signal markers
For example, In the event of injury, cells in the connective tissue will send out histamine molecules
Causes vasodilation, causing redness and heat, which increases the injured cells metabolic rate so they may repair themselves faster
Histamines and other inflammatory molecules will increase the permeability of blood vessels, causing nearby capillaries to release protein ridden fluids that cause swelling.
Symptoms like hat and swelling attract immune cells such as phagocytes and lymphocytes to start consuming the invading pathogens

What are the actual lines of defense coming to defend the body from intruders and pathogens?

Phagocytes are some of the first defense cells on the scene. Their name is directly translated to “to eat” and they indiscriminately consume invaders.
Neutrophils are the first type of phagocytes. THey are the most abundant types of white blood cells and after eating a pathogen will self destruct. They are released by injured skin cells in a process known as leukocytosis.
Macrophages are the bigger phagocytes and often the second line of defense. They are white-blood cells that have occupied tissues and organs. Some will freely move around and consume intruders, while others remain bound to the tissue or organ and defend against intruders. Unlike neutrophils, macrophages do not self-destruct after consuming a pathogen. They can consume and neutralize harmful invaders over and over again.
When the phagocytes defenders run into more pathogens than they can consume, they will signal the hypothalamus to raise body temperature, or cause a fever. This heat allows for cells increase their metabolism to heal themselves faster and also helps kill harmful cells.
Natural Killer Cells are another form of defense cell. They travel through the blood and lymph and seek out abnormal cells to kill. They are unique in that they may attack your own cells if they have become infected with viruses or have become cancerous.
If the natural killer cells detects a malevolent cell, it will introduce it to an enzyme that triggers cell death, or apoptosis.

However, sometimes your body is facing a more pervasive, dangerous intruder or illness. In this case, the innate defense system is not sufficient for defense, which is where the adaptive (or specific) immune system comes in.

Adaptive Immune system

Unlike the innate immune system, the adaptive immune system is not automatically activated and must be introduced to a specific pathogen and recognize it as as a threat before it will attack
You are not born with it, and it must be developed over time as your body comes into contact with harmful outsiders. This may occur randomly or be premeditated, which occurs through vaccination
Once it's been introduced to a threat, the adaptive defense will never forget it. This is one of the key differences between adaptive and innate defenses, for innate defense attack indiscriminately and do not recognize specific threats.
The adaptive system is also systemic, fighting throughout the whole body rather than one region.
Can be split into two defenses: humoral immunity and cellular defenses
Humoral Immunity: Works by dispatching antibodies, or special white blood cells that patrol the blood and lymph
They combat the bacteria and viruses in the spaces between cells
SO HOW does humoral immunity work exactly?
The adaptive immune system must first be able to recognize antigens, an invader such as a bacteria, virus, toxin, fungus, or diseased cell in your own body. Upon recognition, the immune system will flare up and take action.
B lymphocytes can be considered one of the first lines of defense for the humoral response. The B cell originates from and matures in the bone marrow and develops immunocompetence - ability to recognize and bind to a specific antigen, and self-tolerance - ability to not attack the body’s own cells.
When it has reached maturity, the B cell will have over 10,000 bound antibodies on its surface (every b cell has unique bounded antibodies)
When a B cell finally meets an antigen it has the unique antibodies for, it will recognize and bind to it. This activates large-scale replication of the cell, producing an army of cells with the same antibodies and with the same instructions of finding and fighting the same antigen.
Effector and memory cells are produced. Effector cells are the warriors who mass produce antibodies for a specific antigen at a rate of around 2000 antibodies per second.
Antibodies don’t do the killing themselves, but they use the strategy of neutralization, where they physically block binding sites on the antigens to prevent access to body tissues. They also signal the innate immune system, calling in phagocytes and special lymphocytes to kill the antigens
Some of the replicated B cells will become memory cells. Memory cells remain even after the antigen has been defeated, and they allow for a faster and stronger immune response in the future if the antigen is ever introduced again.

When the innate and humoral systems have failed and the cell themselves have been breached, cells must now fight within or among themselves to get rid of pathogens.

The key here is the T lymphocyte cell. T cells go after hijacked cells and cause inflammation, activate macrophages, and activate other T cells. T lymphocytes and other phagocytes in innate immune system engage in a specific process where after consuming the harfum pathogen, they will break the pathogen into small pieces and display them on protein grooves on surface of the cell.

These proteins are called major histocompatibility complexes, or MHCs. The cells that do this are known as professional antigen presenting cells, and they include macrophages and b cells. When the antigen presenting cells bind to the antigen fragments, which are now presented on their surface, they allow T cells to recognize the antigen fragments.

Several different types of T cells: two most important are the helper T cells and the cytotoxic cells

Helper Ts: Can’t actually kill pathogens but will activate other cells that can

When the Helper T cells bind to the MHCs that have antigens compatible with the T cell’s antibodies, it will be activated and replicate rapidly, sending out warning signals known as cytokines to alert the immune system of a problem. These cytokines will often activate cytotoxic cells.

Cytotoxic cells are the cells that do the actual killing of pathogens

They roam the blood and lymph, looking for infected cells to dispose of. It does this by triggering apoptosis in the infected cells through enzymes.

Segment 3: Connection to the Course

Ok, so why is the immune system so important? The immune system is your bodies primary defense system against any harmful bacteria, virus, or in general dangerous outside substances. It is active every second of the day, constantly recognizing and defending against intruders and keeping you healthy. The immune system uses a variety of cells, tissues, and organs to function, also employing different enzymes and proteins. Cell and chemical signalling are vital communication components of the immune system that help target and kill pathogens, whether this may be through consumption or apoptosis. Even though immune systems vary in complexity among different organisms, basic, innate immune responses still exist in every being that are geared towards the organism’s survival. Without a properly functioning immune system, any living thing, no matter how advanced or developed, will have a very short lifespan.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

WeVideo Licensed Music: MegaMusic

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Endocrine System

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Arthur Kim and I am your host for episode #84 called Unit 4 Cell Communication and Cell Cycle: The Endocrine System. Today we will be discussing the role of the endocrine system in cellular signaling and communication.

Segment 1: Introduction to The Endocrine System

The endocrine system is the means by which cell signals released by internal glands travel towards their destinations.
Endocrine signaling is how cell signals are transmitted across long-distances. A gland releases a signal into a circulatory system, usually the bloodstream, where it is carried about until it is picked up by the appropriate receptor.

Segment 2: More About The Endocrine System

As the body is relatively large, it is essential for signals to be able to be transmitted across large distances.
The pituitary gland, the so-called “master gland,” is located just slightly below the brain -- however it is responsible for regulating functions across the entire body.
Example -- When sodium levels in the bloodstream rise, the pituitary gland sends antidiuretic hormones into the bloodstream where they are eventually circulated to the kidneys, which respond by releasing water into the bloodstream.
The pituitary gland also uses the endocrine system to circulate hormones to other glands in order for them to release hormones when needed.
It directs the thyroid gland, located in the neck, in order to control metabolism.
It also directs the adrenal glands, located in the kidneys, which produce numerous hormones like adrenaline, aldosterone and cortisol.

Segment 3: Connection to the Course

As cell signaling across long distances is central to our functions, the endocrine system is essential in allowing for us to exist the way we do. The ability for cells to communicate across long distances has allowed for life to grow and become more complex.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Nervous System

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Saarim Rizavi and I am your host for episode # 83 called Unit 4 Cell Communication and Cell Cycle: The Nervous System. Today I will be discussing everything there is to know about the Nervous System. I’ll start off by giving a brief introduction into what the nervous system exactly is, the parts of the nervous system, what these parts themselves consist of, and the function of these parts. I will then get into how the nervous system develops as one grows older and the many life-debilitating and common diseases of the nervous system. I will finally place the nervous system into the broader topic of cell communication and the cell cycle by talking about the cells of the nervous system, the cell signaling pathway of the nervous system, and basically how neurons communicate with one another. So, basically, I’ll be talking about how the nervous system actually works. I actually want to study neuroscience in the future which is focused on the brain and its impact on behavior and our functions and the main focus of the field is how the brain sends messages throughout your body through the nervous system. So I’m happy to be talking about this topic and I hope you guys find it interesting too. Before I begin, I would like to give credit to some of the websites and resources that were used to create this podcast. These include, lumen learning, mayoclinic, the National Institute of Health, News-Medical.net, livescience.com, and Khan Academy.

Segment 1: Introduction to The Nervous System

What is the nervous system?
A complex network of nerves and cells that carry messages to and from the brain and spinal cord to different parts of the body
The main controlling, regulatory, and communicating system in the body and is known to be the most complex and highly organized body system
The center of all mental activity including thought, learning, and memory.
Responsible for maintaining and regulating homeostasis
Allows us to interact and understand our environment and surroundings, internally and externally
Has 2 main parts, the central nervous system and the peripheral nervous system
The Central Nervous System
Made up of the brain, spinal cord, and neurons
The brain controls many of the body’s functions including sensation, thought, movement, awareness, and memory
The surface of the brain is the cerebral cortex - associated with perception, memory, association, thought, and voluntary physical action
The largest part of the brain is the cerebrum - responsible for things such as memory, speech, voluntary behaviors, and thought.
The cerebrum is divided into the right and left hemispheres
The right hemisphere controls movements on the body’s left side, while the left hemisphere controls movements on the body’s right side
The hemispheres are divided into the frontal lobe, the occipital lobes, the parietal lobes, and the temporal lobes
The spinal cord connects to the brain via the brain stem and runs down through the spinal canal, located inside the vertebra.
The spinal cord carries information from various parts of the body to and from the brain and in the case of some reflex movements, responses are controlled by spinal pathways only
Neurons are the building blocks of the central nervous system.
Billions of these neurons can be found throughout the body and communicate with one another to produce physical responses and actions.
The Peripheral Nervous System
Made up of nerves that branch off from the spinal cord and extend to every part of the body
Main role of the peripheral nervous system is to connect the central nervous system to the organs, limbs, and skin
Nerves extend from the central nervous system to the outermost areas of the body
The peripheral nervous system allows the brain and spinal cord to receive and send information to other areas of the body, which then allows us to react to stimuli in our environment
Divided into the somatic nervous system and the autonomic nervous system
The somatic nervous system - responsible for carrying sensory and motor information to and from the central nervous system
Contains motor neurons, which carry info from the brain and spinal cord to muscle fibers throughout the body, and sensory neurons, which carry info from the nerves to the central nervous system
The autonomic nervous system - responsible for regulating involuntary body functions
It is divided into the parasympathetic nervous system and the sympathetic nervous system
The parasympathetic system helps control bodily functions when a person is at rest - digestion, metabolism, and just helping the body relax
The sympathetic nervous system prepares the body to expend energy to respond to environmental threats by regulating the flight-or-fight response
3 parts of neuron - cell body, dendrites, axons
Glial cells - non-neuron cells that perform many important functions that keep the nervous system working such as supporting and holding neurons in place, regulating neurotransmitters, creating insulation called myelin which helps move nerve impulses, and more

Segment 2: More About The Nervous System

How the nervous system develops over time:
After the fetus is conceived, it takes around 3-4 weeks before one of the two cell layers of the human embryo begins to thicken and build up along the middle
The cells grow and form a flat area called the neural plate which has parallel ridges across its surface; these ridges fold in toward each other and fuse to form the hollow neural tube
The tube thickens at the top and forms three bulges that form the hindbrain, midbrain, and forebrain
The embryo has 3 layers that undergo many changes to form organs, bone, muscle, skin, and neural tissue
The skin and neural tissue arise from one of the layers called the ectoderm
Once the ectoderm starts becoming neural tissues due to specific signals, increased signaling interactions determine which type of brain cell forms - some form the neurons while others form the glial cells
The neurons, which are immature at this time, migrate and start making transient connections with other neurons before reaching their destinations - and they reach their destinations through using glial fibers and contractile proteins.
Neurons generally move from the central canal in the neural tube to the brain where they collect together and connect and form various brain structures.
The neurons move from the neural tube’s ventricular zone, or inner surface, to near the border of the marginal zone, which is the outer surface.
Once they stop dividing, they form an intermediate zone where they gradually accumulate as the brain develops.
Once the neurons reach their final locations, they must make proper connections for particular functions to occur.
Diseases of the nervous system (neurological disorders)
WHO: there is ample evidence that neurological disorders are one of the greatest threats to public health - nearly 1 in 6 of the world’s population, or 1 billion people, suffer from neurological disorders
0.01 neurologists per 100,000 people in low income areas where these diseases are most prominent
Alzheimer’s disease
A progressive neurological disorder that causes the brain to shrink and brain cells to die
It is the most common cause of dementia, which is a continuous decline in thinking, behavioral and social skills, and a decline in the overall ability of a person to function independently
The causes of Alzheimer’s aren’t fully understood but at a basic level, brain proteins fail to function normally, which disrupts the work of neurons and triggers a series of toxic events in which neurons are damaged and lose connections to each other and eventually die
Scientists believe that for most, Alzheimer’s is caused by a combination of genetic, lifestyle, and environmental factors that affect the brain over time.
Parkinson’s disease
A brain disorder that leads to shaking, stiffness, and difficulty with walking, balance, and coordination
As the disease progresses, people may have trouble walking and talking; could also have mental and behavioral changes, sleep problems, depression, memory difficulties, and fatigue
The disease occurs when neurons in an area of the brain that controls movement become impaired and die - these neurons would have produced dopamine, an important brain chemical messenger that’s involved in reward, motivation, memory, attention, and the regulation of body movements
When these neurons die, less dopamine is produced which causes the movement problems seen in Parkinsons
Scientists still don’t understand what causes cells that produce dopamine to die
People with Parkinson’s lose the nerve endings that produce norepinephrine, the main chemical messenger of the sympathetic nervous system - the loss of norepinephrine may explain some of the non-movement features of Parkinson’s like fatigue, irregular blood pressure, and decreased movement of food through the digestive tract.
Epilepsy
Epilepsy is a neurological disorder in which brain activity becomes abnormal, causing seizures or periods of unusual behavior, sensations, and loss of awareness
Some people with epilepsy just stare blankly for a few seconds during a seizure, while others twitch their arms or legs repeatedly
At least 2 unprovoked seizures are required for an epilepsy diagnosis
Epilepsy has no identifiable causes in about half the people with the condition; in the other half, the condition may be traced to a variety of factors including genetic influence, head trauma, brain conditions, like brain tumors or strokes, infectious diseases, like meningitis and AIDS, prenatal injury, and developmental disorders, like autism.

Segment 3: Connection to the Course

Parts of a neuron
Cell body (soma) - contains a nucleus, smooth/rough ER, a golgi apparatus, mitochondria, and other cellular components
Dendrites - branch-like structures extending away from the cell body; their job is to receive messages from other neurons and allow those messages to travel to the cell body
Axons - tube-like structures that carry electrical impulses from the cell body or from another cell’s dendrites to the structures at the opposite end of the neuron, known as an axon terminal, which can then pass the impulse to another neuron
Synapses - chemical junctions between the axon terminals of one neuron and the dendrites of another; a space between two neurons where they can pass messages to communicate
Cell signaling/cellular communication in the nervous system
Neurons exist in a fluid environment - they are surrounded by extracellular fluid and contain intracellular fluid - the neuronal membrane keeps these two fluids separate which is important because the electrical signal that passes through the neuron develops on these intracellular and extracellular fluids being electrically different
This difference in charge across the membrane, called the membrane potential, provides energy for the signal
The electrical charge of the fluids is caused by ions dissolved in the fluid
The semipermeable nature of the neuronal membrane somewhat restricts the movement of these charged molecules - some of the charged particles tend to become more concentrated either inside or outside the cell
Between signals, the neuron’s membrane potential is in a state of readiness known as the resting potential.
In this state, ions are lined up on either side of the cell membrane, ready to rush across the membrane when the neuron goes active and the membrane opens its gates (sodium-potassium pump that allows the movement of ions across the membrane)
In the resting state, sodium ions are at a higher concentration outside the cell so they will tend to move into the cell while potassium ions are more concentrated inside the cell and so will move out of the cell
The inside of the cell is slightly more negatively charged compared to the outside of the cell in the resting state and so this also causes sodium to move into the cell
From this resting potential state, the neuron receives a signal at the dendrites, in the form of a chemical messenger known as a neurotransmitter binding to its receptors - as a result, small pores open on the neuronal membrane, allowing sodium ions to move into the cell - causes the internal charge of the cell to become more positive - the charge reaches a certain level called the threshold of excitation and then the neuron becomes active and the action potential begins
Many additional pores open, causing a massive influx of sodium ions and a positive spike in the membrane potential, known as the peak action potential.
At this peak, the sodium gates close and the potassium gates open and potassium ions leave the cell - this results in the neuron’s membrane returning to its resting state
The action potential is an electrical signal that moves from the cell body down the axon to the axon terminals - the action potential is propagated at its full strength at every point along the axon...

Intro to Signaling Transduction Pathway

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Nikki Evich and I am your host for episode

#82 called Unit 4 Cell Communication and Cell Cycle: Intro to Signaling Transduction Pathway. Today

we will be discussing the components that make up a pathway.

Segment 1: Introduction to the signaling transduction pathway

● Signal also call ligand binds to a receptor on target cell membrane

○ , starts the pathway,

○ had to fit receptor,

○ once bound, transduction is initiated

● Receptor- intracellular or extracellular

○ Binding domain recognizes specific chemical messengers

● transduction-lots of varian with transduction

○ Could activate inactive protein by phosphorylating

○ Amplifies with secondary messengers

● Response- what the end result is

○ Can be short or long

○ Activate enzyme or move cell-short

○ Alter gene expression levels or cell division (apoptosis)-long

Segment 2: More About the signaling transduction pathway

● Type 1

● Once the food is broken down into glucose, these molecules are then absorbed into the bloodstream.

The high glucose levels in the bloodstream activate the beta cells in the pancreas to start producing

insulin. Insulin is a hormone created in the pancreas. In the pancreas, beta cells are present which are

in charge of secreting the insulin into the bloodstream once they detect an increase in blood glucose.

Insulin travels to three main destinations-muscle, fat, and liver cells.

● This is where the transduction pathway happens

● The insulin will then bind to the insulin receptors. The insulin receptors are made up of extracellular

alpha subunits and transmembrane beta subunits.

● When the insulin binds to the extracellular alpha subunits, the beta subunits become activated and auto

phosphorylate. This means that they phosphorylate themselves.

● This leads to the phosphorylation and activation of the IRS protein. The IRS protein is regulated and

can be phosphorylated by PTEN. PTEN can regulate phosphorylation and activate IRS Isaforms by

dephosphorylating IRS. Once IRS is activated, proteins including PI3K will bind to the IRS protein

through their P85 subunit.

● The PI3K will then phosphorylate PIP2 to PIP3. When the PIP3 concentration increases, other proteins

like PDK1 and AKT are recruited towards the plasma membrane. PIP3 activates PDK1 which then

phosphorylates AKT.

● Cells have reservoirs of intracellular vesicles that contain GLUT4, a glucose transporter. So in order for

glucose to be let into the cell the glucose transporters have to translocate to the plasma membrane.

However, AS160 inhibits this process.

● Luckily, phosphorylated AKT inactivates AS160. So when AKT is phosphorylated by PDK1, AS160 is

inactivated which in turn allows for the translocation of glut 4 so it can embed itself in the membrane.

Now glucose can get into the cell for storage and other purposes.

Segment 3: Connection to the Course

● Involved in evolution-some cell transduction pathways stayed the same

○ Track common ancestors Interruptions in this pathway are serious like with the brain sending

signals out

● Involved in negative feedback loops and homeostasis

● Body is constantly sending signals, though it may seem minute it makes you be able to do all you do

● In all walks of life

● Can be seen in all types of diseases and illness from Diabetes to cancer

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts

and digital content, make sure that you visit www.hvspn.com. Bye now!

Music Credits:

● "Ice Flow" Kevin MacLeod (incompetech.com)

● Licensed under Creative Commons: By Attribution 4.0 License

● http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Cell Communication

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 4 Cell Communication and Cell Cycle

Welcome to My AP Biology Thoughts podcast, my name is Shriya Karthikvatsan and I am your host for episode #81 called Unit 4 Cell Communication and Cell Cycle: Cell Communication. Today we will be discussing how cells communicate with one another and how they do over long and short distances.

Segment 1: Introduction to Cell Communication

So, the topic of cell communication focuses on how a cell gives and receives messages with its environment and within itself because a cell’s survival depends on its ability to receive and process information outside its environment
The cell membrane plays a key role in a cell’s response to environmental signals because there are chemical and physical signals that a cell has to respond to via receptors
In membrane signaling, proteins shaped into receptors are embedded in the membrane which connect the triggers in the external environment to the ongoing dynamics inside a cell
In addition, ion channels allow the direct passage of molecules between external and internal compartments of the cell
Cells have evolved a variety of mechanisms to be able to transmit important biological information and some examples include:
The development of growth factors that interact with the cell membrane and can trigger receptors that powerfully affect the modulation of gene expression
Metabolites in the blood that can trigger a cell's receptors to cause the release of a hormone needed for glucose regulation
Now, we will go into an overview of cell communication and some important terms to note
Since we know cells communicate using signals, we should also know that these chemical signals are proteins produced by a “sending cell” which are released into the extracellular space where the signal can be “heard”
In order to detect a signal, or to be a target cell, a neighbor cell must have the right receptor for that signal
When a signaling molecule binds to its receptor, it alters the shape or activity of the receptor, triggering a change inside of the cell and signaling molecules are often called ligands
The message carried by a ligand is often put through a chain of chemical messengers inside the cell which leads to a change in the cell, such as alteration in the activity of a gene or cell division
Finally, the original intercellular (between-cells) signal is converted into an intracellular (within-cell) signal that triggers a response
You can see what I am talking about in the diagram below:
In the next segment, we will go more into detail of the 4 types of cell signaling, their meanings, and why they are important

Segment 2: More About Cell Communication

Cell-cell signaling involves the transmission of a signal from a sending cell to a receiving cell, but not all cells exchange signals in the same way because cells are exposed to many signals and may have different responses
The 4 basic categories of cell signaling are, autocrine, juxtacrine, paracrine, and endocrine signaling with the main differences between them being the distance that the signal itself travels
So, first, in autocrine signaling, the cell signals to itself and a great example of this are tumor cells because of their ability to produce and respond to their own growth factors
The cell releases a ligand that binds to receptors on its own surface or to receptors inside of the cell
This signaling is important because during development, cells take on their own identities and reinforce them
In juxtacrine signaling, direct contact between cells is required, and the transfer of signaling molecules transmits the current state of one cell to its neighbor which allows a group of cells to coordinate their response to a signal that only one of them may have received
This is especially important for responses in the immune system and with recognition
Below is a diagram of an immune system cell recognizing a healthy cell:
When the proteins bind to one another, this interaction changes the shape of one or both proteins, transmitting a signal
This kind of signaling is especially important in the immune system, where immune cells use cell-surface markers to recognize the body's own cells and cells infected by pathogens
Next, in paracrine signaling, signals bind through communication over relatively short distances through the release of chemical messengers
This type of signaling is important because it allows cells to communicate with other nearby cells and during development when they allow one group of cells to tell a neighboring group of cells what cellular identity to take on
A type of paracrine signaling is synaptic signaling in which nerve cells transmit signals through the synapse which is the junction between two nerve cells where signal transmission occurs
Finally, the last type of signaling is called endocrine sigaling which occurs when cells need to transmit signals over long distances where the circulatory system is often used as a way for the messages to be transmitted
Signals are produced by specialized cells and released into the bloodstream which carries them to target cells in other parts of the body
Signals that are produced in one part of the body and that travel through the circulation to reach other “far-away” targets are called hormones
Endocrine glands that secrete hormones are called thyroid, the hypothalamus, and the pituitary, and each one releases one or more types of hormones, many of which are strong regulators of development and physiology
Below is a diagram of how this signaling works and you can see how the message is sent through the bloodstream between two different cells

Segment 3: Connection to the Course

Cell communication fits into the bigger picture of this unit which is cell communication and the cell cycle because in order for the body to function properly, the cells need to work together through communication and signals
This process is important because it allows cells to fine-tune their functions and be able to communicate well and errors in communication can be detrimental and lead to cancer or diabetes which is why the cell cycle is also so important

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Fitness (Molecules & Metabolic Pathways)

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode #80 called Unit 3 Cellular Energetics: fitness. Today we will be discussing molecules and metabolic pathways

Segment 1: Introduction to Fitness

This is a much different type of fitness taught back in the evolution unit. This fitness is in energetics and we mainly look at the variation in molecules that allow the organism to survive and/or reproduce in a different environment. The whole point of this fitness is to see how organisms change when a new condition is introduced. For reference, when we stand still and have normal amounts of oxygen, our body uses aerobic respiration, meaning we get energy from the oxygen around us and our body goes through cellular respiration. However when we are running or going through conditions with limited amounts of oxygen, our body switches over to anaerobic respiration. This switch still allows us to get energy, however not as much. This change shows us how fit we are and ties into how our body changes with the different environment. However, that example was just a general overview, in fitness we look at the specific molecules.

Segment 2: More About Fitness

If we want to look at more examples we have to separate plants and animals. A main example of important molecules that provides for the animal is hemoglobin. This cell is found in the blood, and this is the main transporter of oxygen throughout the body. The oxygen bonds to these molecules and it is then transported through the bloodstream to all of the different cells. However, hemoglobin changes and adapts to its environment. We see that hemoglobin binds to oxygen differently throughout stages of life. For fetuses, their hemoglobin is different in terms of more oxygen being able to bond to it. This is because fetuses do not expend as much energy as an adult, however it needs more oxygen for metabolism and growth. The fetal hemoglobin then is able to attach to more oxygen molecules, however that means it is much harder to get oxygen off of the hemoglobin. This is why adults use a hemoglobin that attaches to less oxygens, but it is easier to separate. Now for plants, the main example of fitness is chlorophyll. With low amounts of light, the plant typically uses chlorophyll b which is more of a pigment than a center for photosynthesis. With higher levels of light, the plant typically uses chlorophyll a, which is the main reaction center.

Segment 3: Connection to the Course

This directly relates to the unit by connecting cellular respiration to the real world. We learn about aerobic and anaerobic, however we don’t learn when we use them and under what conditions. But more importantly, we don’t learn what the molecules do to adapt to this. This chapter allows us to conceptually understand why our body does what it does. It is essential to know the connection between variation in the number and types of molecules within cells that allows the organism to survive under different ecosystems.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Calvin Cycle

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Saarim Rizavi and I am your host for episode #79 called Unit 3 Cellular Energetics: The Calvin Cycle. Today we will be discussing the second stage of photosynthesis known as the Calvin Cycle (or the light-independent reactions). We will be talking about what the calvin cycle is in the first place and I will give a brief overview of the whole process. Then, I will go into the specific reactions of the calvin cycle and the three main steps of the calvin cycle which include carbon fixation, reduction, and regeneration. Finally, to end it off, I will place and discuss the calvin cycle in the scope of the broader topic of cellular energetics and just the overall importance of the calvin cycle to the environment. Before I begin, I would like to give credit to a couple of websites and resources that were used to create this podcast which include sciencing.com, national geographic, khan academy, biology libretexts, and Ms. Ribecca’s AP Biology Cellular Energetics Videos. So thank you to them for making this podcast possible.

Segment 1: Introduction to The Calvin Cycle

Calvin cycle is named Calvin cycle because it was named after Melvin C. Calvin who discovered it and won a Nobel Prize in Chemistry for it
What is the Calvin Cycle?
A process that plants and algae use to turn carbon dioxide from the air into sugar (glucose)
Every living thing on Earth depends on the Calvin cycle either directly or indirectly to survive
The calvin cycle takes place in the stroma - the inner space of the chloroplasts
Function - to create three carbon sugars which can be used to build other sugars such as glucose, starch, and cellulose that is then used by plants to function and survive
Steps of Calvin Cycle (quick overview)
Carbon fixation - organic carbon in the form of carbon dioxide in the air is incorporated into organic molecules
Inorganic carbon converted to organic compounds by living organisms
Reduction - the organic molecules produced in the first stage accept electrons and are reduced
Regeneration - the reduced organic molecules use energy from ATP to make RuBP to start the cycle all over again
Cycle is powered by ATP and NADPH from light dependent reactions

Segment 2: More About The Calvin Cycle

“Preliminary step”
In plants, carbon dioxide enters the leaves through the stomata, which is located on the underside of plant leaves
The CO2 diffuses through intercellular space until it reaches the mesophyll cells - CO2 then diffuses into the stroma of the chloroplast
Stroma - besides the CO2, there’s an enzyme called rubisco and three molecules of ribulose bisphosphate (RuBP) - RuBP = 5 carbon acceptor molecule
Carbon Fixation
A reaction between carbon dioxide and RUBP occurs and produces a 6 carbon compound that splits into 2 molecules of a three carbon compound known as 3-PGA, which has 3 carbons and one phosphate
3 molecules of carbon dioxide react with 3 molecules of RuBP to produce 6 molecules of the 3 carbon molecules, 3-PGA - reaction catalyzed by rubisco
A turn of the calvin cycle involves only 1 RuBP and 1 carbon dioxide molecule forming 2 molecules of 3-PGA - it takes 3 turns of the calvin cycle to produce 6 molecules of 3-PGA
Reduction
The 3-PGA molecules created through fixation are converted into molecules of simple sugar, known as G3P
The 6 molecules of 3 PGA use 6 molecules of ATP and 6 molecules of NADPH, which store the light reactions, to generate 6 molecules of G3P, a 3 carbon sugar
Reduction reaction because the 3-PGA molecules gain electrons - the PGA is basically reduced to G3P
ATP - energy is released with the loss of the terminal phosphate group converting it to ADP
NADPH - both energy and a hydrogen atom are lost, converting it into NADP+; NADPH donates electron to a 3 carbon intermediate to make G3P
One turn of the calvin cycle would produce 2 G3P’s so it takes 3 turns to make 6 G3Ps
NADP+ and ADP molecules can return to the light-dependent reactions then to be reused and reenergized
Regeneration
1 of the 6 G3P molecules leaves the Calvin cycle and is sent to the cytoplasm to contribute to the formation of other compounds, like glucose, needed by the plant
The other 5 of the G3P molecules use the energy from 3 molecules of ATP to produce 3 molecules of RuBP
Regeneration requires ATP and involves a complex network of reactions
Summary of key molecules that enter and exit the calvin cycle
In 3 turns of the calvin cycle:
3 CO2 combine with 3 RuBP acceptors to make 6 molecules of G3P (reduction step)
1 G3P exits the cycle and goes towards making glucose, 5 G3P molecules are recycled and regenerate 3 RuBP acceptor molecules
9 ATP molecules are converted to 9 ADP during the fixation and regeneration steps
6 NADPH are converted to 6 NADP+ during the reduction step
Glucose production
It takes 2 G3Ps to build a 6 carbon glucose molecule - It takes three turns of the carbon cycle to make 1 G3P so to make 2, it takes 6 turns of the cycle to produce 2 G3Ps and 1 molecule of glucose - this would take 6 carbon dioxide molecules, 18 ATP molecules, and 12 NADPH

Segment 3: Connection to the Course

Importance of glucose production as a result of the Calvin Cycle
Glucose is the plant’s food source and it enables the plant to survive, function, and grow
Glucose can be stored in plants - this stored glucose provides the energy to help plants flower
Glucose joins with oxygen in the process of cellular respiration in which glucose and oxygen react to produce energy for the plant in the form of ATP
The same applies for all other heterotrophs which depend on plants for food and their source of energy.
For plants: Glucose molecules form cellulose which builds and adds strength to the cell walls of plant cells.
Glucose molecules also form carbohydrates like starch to store energy for cell metabolism for plants
When glucose is combined with nitrates, glucose will form amino acids - when these amino acids join together, they form proteins, and many structural parts of the plant are made of protein - proteins which are stored in a plant’s embryo and vegetative cells are able to produce carbon, nitrogen, and sulfur resources for subsequent growth and development - protein can also be produced in the form of enzymes which help in catalyzing the reaction of photosynthesis
General importance of Calvin Cycle
Without the calvin cycle, organisms wouldn’t have the food, energy , and nutrients they need to survive
Photosynthesis and the calvin cycle enable cellular respiration because the products of photosynthesis, glucose and oxygen, are the reactants of cellular respiration
Carbon cycle could not occur without the calvin cycle
Relation to Cellular Energetics
Photosynthesis is an endergonic reaction which takes in energy in the form of sunlight to build organic compounds
Photosynthesis is an anabolic reaction since sugars are being formed and joined together during the calvin cycle - also considered nonspontaneous
Enzymes are important in the calvin cycle - the cycle couldn’t occur without the enzyme rubisco catalyzing the reaction between CO2 and RuBP
The calvin cycle and photosynthesis need cellular respiration to occur since cellular respiration produces CO2 and water which can then be used in photosynthesis - CO2 is used and reduced in the calvin cycle.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (And always remember, learning new things doesn’t have to be challenging. It’s really easy once you have a goal in mind and a purpose for everything you do)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Light Dependent Reactions

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Helena Holley and I am your host for episode #78 called Unit 3 Cellular Energetics: Light Dependent Reactions. Today we will be discussing the mechanisms of the first stage of photosynthesis known as the light dependent reactions or non-cyclic photophosphorylation.

Segment 1: Introduction to Light Dependent Reactions

The light dependent reactions is a process in which light energy is converted to chemical energy. In plants, this reaction takes place in thylakoid membranes of chloroplasts. The process involves the use of two photosystems called photosystem I and II. These are embedded in the membrane and they contain many pigments which optimize them for harvesting light. The process involved the use of an electron transport chain to create a proton gradient which is used to make ATP and NADH.

Segment 2: More About Light Dependent Reactions

Now that you have an overview of the light dependent reactions, I'll take you through the process step by step. The reactions begin when photosystem II absorbs light causing an electron to be boosted to a higher level. This electron is passed to an acceptor molecule and it is replaced by an electron from water, which causes h20 to split into ½ O2 and 2 H+ molecules. The O2 released is the oxygen we breathe. The high energy electron that is energized by the light is passed down an electron transport chain. The electron releases energy as it travels through the chain which drives the pumping of H+ from the stroma into the thylakoid lumen, building a gradient. Since this proton gradient is created, the H+ ions will naturally want to flow down it. In order to flow down their gradient back into the stroma, they have to go through the ATP synthase enzyme. This creates ATP from ADP and Pi through chemiosmosis. One of the last locations of the electrons in their electron chain is photosystem I where the electron is boosted to an even higher energy level and transferred to an acceptor molecule. This high energy electron travels down a short final leg of the electron transport chain and at the end it is passed to NADP+ resulting in the creation of NADPH.

Segment 3: Connection to the Course

The light dependent reactions are a significant part of the process of photosynthesis. The ATP and NADPH created in the light dependent reactions is used to power the production of carbohydrates from carbon dioxide. Carbohydrates are a main food source for organisms and are essential for survival. Without light dependent reactions, photosynthesis cannot occur and energy for the photosynthetic organisms would not be created. This would result in the organism dieing. The light dependent reactions are essential to the organisms survival. Enzymes are also a key component of light dependent reactions such as the ATP synthase enzyme. As discussed in the course, enzymes require certain conditions in order to function and their functioning is important to the light dependent reactions.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Keep your plants in the sun!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Photosynthesis: An Overview

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Shriya Karthikvatsan and I am your host for episode # called Unit 3 Cellular Energetics: Overview of Photosynthesis. Today we will be discussing what exactly Photosynthesis is, its importance to life, and the processes that make up it.

Segment 1: Introduction to Photosynthesis

We’re going to start off by discussing exactly what photosynthesis is, its importance, and a brief overview of the different stages of it
Photosynthesis is when light energy is captured by photosynthetic molecules that are broken down in cellular respiration to obtain energy (ATP)
Essentially, glucose molecules (or other sugars) are constructed from water and carbon dioxide, and oxygen is released as a byproduct
Also, the carbon in CO2 is used to make carbs and other organic molecules that the organism requires to survive
The process of producing the organic molecules is called carbon fixation where the carbon in CO2 is “fixed” and incorporated into sugars to be used to build the organic molecules
Photosynthesis is important because photosynthetic organisms such as plants, algae, and bacteria play a key role
They introduce chemical energy and help fix carbon by utilizing light energy, meaning they can produce their own food and are therefore called photoautotrophs
Since humans and other organism cannot convert carbon dioxide to organic compounds, they rely on the autotrophs for these compounds and to receive energy
Also, photosynthesis is important because it produces oxygen as a byproduct which affects the Earth’s atmosphere and removes carbon dioxide from the atmosphere, preventing a gas buildup that would be detrimental to us
Photosynthesis simplified can be divided into two stages: the light-dependent reactions and the Calvin Cycle
The light-dependent reactions occur in the thylakoid membrane and require light energy
The Calvin Cycle, or light-independent reactions, takes place in the stroma and doesn’t require light
In the next segment, we are going to go more in depth about these two processes and the specific significant parts of a plant involved in them

Segment 2: More About Photosynthesis

Okay to start we are going to go over the important parts of a plant involved in photosynthesis you should know
Photosynthesis itself takes place in the chloroplast of a plant which contains chlorophyll which is the pigment that absorbs different wavelengths of light from the energy source
The chloroplasts are surrounded by a double membrane and have a third inner membrane called the thylakoid membrane where light-dependent reactions take place
The stroma is the fluid and space in the chloroplast
Here is a diagram of both parts of photosynthesis
The first part of photosynthesis, the light-dependent reactions, are when light energy is converted into chemical energy
This energy conversion occurs through the formation of two compounds: ATP (energy storage molecule) and NADPH (electron carrier)
Water molecules are also converted into oxygen gas
This entire process wouldn’t occur without help from photosystems 1 and 2, and the electron transport system which produces NADPH for the Calvin cycle
PS 2 absorbs light energy to excite electrons to produce ATP
The electrons come from splitting hydrogen atoms in H2O
The protons activate ATP Synthase, an enzyme, and form a gradient
PS 1 excites electrons again to reduce NADP+ to NADPH
The next part of photosynthesis, is the Calvin cycle, where carbon is fixed using NADPH and ATP produced by the light-dependent reactions
It takes place in the stroma and doesn’t require light
It begins with carbon fixation which attaches to RuBP, an organic substance, which is catalyzed by the enzyme rubisco
It produces an unstable 6-Carbon molecule that splits into 2 3-PGA
Then, the Calvin cycle continues on with reduction where the 3-PGA is reduced, and NADPH is oxudized to form G3P
Finally, regeneration occurs in the cycle of RuBP because 5G3P molecules are used for RuBP and 1G3P is used in other processes, hence why it is a cyclic process

Segment 3: Connection to the Course

Overall, this unit was about cellular energetics and how all living things require energy to function
The energy itself can come from a variety of sources, and it is neither created nor destroyed, it is transformed
In photosynthesis, we viewed light energy transformed into chemical energy
Photosynthesis is just one of the processes that produces energy for organisms and that ATP is created in both the light-dependent reactions and Calvin Cycle
Like photosynthesis, cellular respiration is another source of energy for living organisms
They differ in the form of energy absorbed or released
However, they both involve a series of redox reactions where molecules are reduced and involve an electron transport chain
In cellular respiration, electrons flow from glucose to oxygen, forming water and releasing energy
In photosynthesis, they go in the opposite direction, starting in water and winding up in glucose through an energy-requiring process powered by light
As you can see, photosynthesis is just one of the many processes that produce energy and organic compounds for living organisms to function, but it is different in the specific molecules it utilizes

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Anaerobic Respiration

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Adrienne Li and I am your host for episode #76 called Unit 3 Cellular Energetics: Anaerobic Respiration. Today we will be discussing what anaerobic respiration is, the two types, examples, and its connection to the rest of unit 3.

Segment 1: Introduction to Anaerobic Respiration

To start off, let me define what anaerobic respiration is. It is the process that regenerates NAD+ for glycolysis so it can produce ATP and its key characteristic is that it occurs when oxygen is not available. This distinguishes anaerobic from aerobic respiration, which occurs when oxygen is available. Also, it’s important to stress that its main purpose is to regenerate NAD+ which is a big misconception that many people have.

Segment 2: More About Anaerobic Respiration

Diving deeper into anaerobic respiration, there are two types. One is alcohol fermentation which occurs in plants, fungi, and bacteria. It starts out with glycolysis where glucose is converted into pyruvate, but since oxygen is not present, it converts into CO2 and acetaldehyde. Then, energy from NADH is applied to acetaldehyde and converts into ethanol and NAD+, thus regenerating the NAD+ that is necessary for glycolysis to occur and produce 2 ATP. A real life example is seen in yeast, where they use alcoholic fermentation which allows bread dough to rise. This is because CO2 is a waste product of alcoholic fermentation which causes gas bubbles to form. The other type of anaerobic respiration is lactic acid fermentation which occurs in animals. Similar to alcohol fermentation, it uses glucose to create pyruvate but then it is converted to lactate instead of acetaldehyde and lactic acid is produced instead of CO2. During this process, NADH is oxidized into NAD+ which is used in glycolysis to produce 2 ATP. This occurs when we exercise which we feel through the burning sensation during a tough workout. The burning sensation is lactic acid build up, which occurs when our respiratory and cardiovascular systems cannot transport oxygen to our muscles fast enough. Therefore, they resort to lactic acid fermentation to immediately produce ATP.

Segment 3: Connection to the Course

To connect anaerobic respiration to the rest of the unit, let’s zoom out a bit to the bigger picture of cellular energetics. Keep in mind, anaerobic respiration does produce energy, that’s just not its main purpose. With the regeneration of NAD+, it is used in glycolysis to produce 2 ATP. Other cellular pathways that exist include the krebs cycle and chemiosmosis, however they don’t occur in anaerobic respiration because oxygen isn’t present. They do however occur in aerobic respiration because oxygen is present and acts as the final electron acceptor. This aids in the formation of a proton gradient along with the energy of the electrons from NADH and FADH2 which actively transports H+ into the intermembrane space. From there, chemiosmosis occurs where H+ flows from high to low concentration and back into the matrix through ATP synthase, which then creates ATP. This is a brief explanation of aerobic respiration but it shows the different processes that occur in both due to the presence or absence of the final electron acceptor oxygen. So that about sums up anaerobic respiration and its connection to other cellular energetic pathways.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time bio buddies!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Oxidative Phosphorylation

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline Sun and I am your host for episode #5 called Unit 3 Cellular Energetics: OXIDATIVE PHOSPHORYLATION. Today we will be discussing the formation of ATP in the vital final step of cellular respiration.

Segment 1: Introduction to Oxidative Phosphorylation

Oxidative Phosphorylation is the name for the entire final process in which ATP is created; it can be split into two parts which are the ETC and chemiosmosis.
Is an aerobic process which requires oxygen and follows the Krebs cycle.
Uses 3 NADH and 1 FADH2 produced from the Krebs cycle, also requires oxygen as the final electron acceptor.
The final product of Oxidative Phosphorylation is, of course, ATP. A byproduct is H2O.
Takes place in the inner membrane of the mitochondria, involves 4 protein complexes labeled with roman numerals 1-4 from left to right and an ATP synthase that are all embedded within the membrane.

Segment 2: More About Oxidative Phosphorylation

ETC

There are two electron carriers which will start the ETC: NADH and FADH2. I will first talk about NADH, because the process for FADH2 is slightly different. The electron carrier NADH is oxidized into NAD+, losing two electrons which are pumped into protein I. This energy transfer allows one H+ ion (lost from the NADH) to be actively transported into the intermembrane space. The H+ must be actively transported because there is a higher concentration of H+ in the intermembrane space than in the matrix. The electrons are then transferred by a transfer protein to protein III , and the energy that is lost in the transfer is again used to pump an H+ ion into the intermembrane space. Finally the lower-energy level electrons are transported once more to protein IV, and the energy lost in the transfer is used to pump another H+ over. At this point, the 2 electrons are much lower in energy level and must be removed to prevent a backup of electrons, so they will exit the last protein complex and bind with two free-flowing H+ ions and ½ of an O2 molecule to create H2O. This is how oxygen acts as the final electron acceptor and how it contributes to the creation of the byproduct of H2O. In summary, by the end of the process, NADH has pumped 3 total electrons. Now let's talk about FADH2. FADH2 is the other electron carrier and is oxidized at protein II, losing two electrons to be pumped into the ETC and turning into FAD and two H+ ions. It will then follow the same process as NADH. The key difference here is that FADH2 starts at protein II while NADH starts at protein I, meaning FADH2 will only pump two protons, making it slightly less efficient than NADH.

Chemiosmosis (compared to previous process, considerably more straightforward)

Overall, ATP synthase, the central protein complex of chemiosmosis, will convert the potential energy of the proton gradient into chemical energy in ATP. Due to the ETC, there is a higher concentration of protons in the intermembrane space and lower conc. in the matrix, the protons in the higher conc. will naturally want to move down their electrochemical gradient into the matrix. The H+ ions will pass through the ATP synthase back into the matrix. The energy derived from the movement of these protons down their gradient and through the ATP synthase allows for phosphorylation, or the binding of Phosphate to ADP, to occur. From this, we have finally created ATP, and the cycle of cellular respiration is complete.

Segment 3: Connection to the Course

Oxidative Phosphorylation is extremely important, for it is the last component of cellular respiration, one of the most important life functions that generates an organism’s energy in the form of ATP. Without this energy, I would not be speaking here right now, and all life in general would cease. Large quantities of ATP cannot be created without this process, but at the same time Oxidative Phosphorylation cannot occur without the other processes such as glycolysis, pyruvate oxidation, and the Krebs cycle. Just as glycolysis produces pyruvate to be used in the Krebs Cycle, the Krebs Cycle will produce the two electron carriers required for Oxidative Phosphorylation to start. Oxidative Phosphorylation is the important ending piece of the puzzle of Cellular Respiration, and only with its occurrence can we live our lives.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (See you next time)!

Music Credits:

WeVideo Music: Inspiration - Mega Music

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Krebs Cycle

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Episode #74 Krebs Cycle

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 74 called Unit 3 cell energetics: the Krebs Cycle. Today we will be discussing the Krebs Cycle.

Segment 1: Defining The Krebs Cycle

The Krebs cycle, also known as the citric acid cycle, is the third step in cellular respiration, the process by which organisms combine oxygen and other molecules into energy that is used in life-sustaining activities. Before the Krebs cycle, glycolysis and pyruvate oxidation occur.

The Krebs cycle occurs in the mitochondrial matrix in eukaryotes. The matrix of the mitochondria is the part of the mitochondria inside the inner membrane. This process occurs twice for every glucose molecule that goes through glycolysis. The Krebs cycle is a very detailed process.

First, acetyl coenzyme A, which was produced in the previous step of cellular respiration, combines with oxaloacetate to form citrate. This molecule is converted to its isomer, which is then oxidized and releases carbon dioxide. During this process, NAD+ is reduced to form NADH. Next, another molecule is oxidized and NAD+ is again reduced to NADH, and a molecule of carbon dioxide is released. THe coenzyme A of succinyl coensyme A is replaced by a phosphate group which is transferred to ADP to produce ATP, or in some cases, GDP. A four carbon molecule called succinate is also produced. Next, succinate is oxidized and FAD is reduced to FADH2. Water is then added to the resulting molecule, and another molecule of NAD+ is reduced to NADH. 2 Oxaloacetate is also produced which allows the cycle to start again.

Those are the very detailed steps of the Krebs cycle, but the most important part to remember is the energy transfers that occur and what the krebs cycle produces. In the Krebs cycle NAD+ is reduced to NADH, and FAD is reduced to FADH2. ADP and phosphate are combined to produce ATP. Citrate is oxidized, and heat is lost in the process. In the end, the krebs cycle produces 4 CO2, 2 ATP, 6 NADH, and 2 FADH2. Carbon dioxide is the waste product and is moved into the blood, and acetyl coa is used to convey the carbon atoms to the cycle.

Segment 2: Examples of the Krebs Cycle

The Krebs cycle is important because it produces molecules that are required for cellular respiration, which enables organisms to create energy that they need to function. The Krebs cycle occurs in all organisms that undergo cellular respiration. It happens in an aerobic environment.

Segment 3: Digging Deeper into the Krebs Cycle

The Krebs cycle also supports the endosymbiotic theory. Prokaryotes go through the Krebs cycle in the cytoplasm. One main aspect of the endosymbiotic theory is that mitochondria used to be prokaryotic cells, but were absorbed by larger cells to form eukaryotic cells with membrane bound organelles. Since eukaryotic cells go through the krebs cycle in the mitochondria, this supports the endosymbiotic theory.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-run podcasts, make sure that you visit www.hvspn.com. See you next time on My AP Biology thoughts podcast!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Pyruvate Oxidation

Hopewell Valley Student Publications Network — Tue, 25 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Pauline Brillouet and I am your host for episode #73 called Unit 3 Cellular Energetics: Pyruvate Oxidation. Today we will be discussing the details and significance of this step of cellular respiration.

Segment 1: Introduction to pyruvate oxidation

Pyruvate oxidation is the second step in cellular respiration. It is often called the link reaction because it bridges glycolysis to the krebs cycle. The process takes place in the mitochondrial matrix of eukaryotes. The reactants are pyruvate and CoA, and the products are carbon dioxide and acetate. It’s whole purpose is to further oxidize the original glucose molecule that how now split into two pyruvate molecules

Segment 2: More About pyruvate oxidation

Pyruvate is a 3 carbon sugar left over from glycolysis. A carboxyl group is removed from pyruvate, releasing carbon dioxide and leaving it as a 2 carbon sugar. Pyruvate was therefore essentially oxidized and lost electrons. These lost electrons are then used to reduce NAD+ to NADH, so NAD+ is gaining an electron. The 2 carbon sugar now called acetate then binds to coenzyme A (CoA) to form acetyl CoA.

Segment 3: Connection to the Course

The process of pyruvate oxidation is essential because of its products. The carbon dioxide that is released is then able to be ingested by plants so that they can perform photosynthesis. The acetyl CoA produced is needed to kick start the next step in cellular respiration called the krebs cycle. Finally, the reduction of NAD+ to NADH is very important because NADH is now an electron carrier that will get oxidized later in the electron transport system. The oxidation of NADH allows for a proton gradient across the inner mitochondrial membrane to diffuse back through the ATP synthase. This process is also helpful to help visualize redox reactions, where reduction must happen with oxidation and vice versa. NAD+ is only able to be reduced because the pyruvate was oxidized. Overall, glucose is simply being further oxidized in this link reaction to ultimately produce ATP for cell work and functioning.
Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Glycolysis

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name Morgan and I am your host for episode #72 called Unit 3 Cellular Energetics: Glycolysis. Today we will be discussing the first step in the process of cellular respiration

Segment 1: Introduction to Glycolysis

Glycolysis is the first of roughly three, kind of three and a half, steps in the process of cellular respiration. It occurs in the cytoplasm of the cell, and is an anaerobic process. This means that it does not require oxygen to occur, although the overall process of cellular respiration does require oxygen. The purpose of glycolysis in cellular respiration is to start the breakdown of glucose in order to extract energy needed for cell work and metabolism, made in the form of ATP. In organisms that do not use aerobic respiration and cannot perform cellular respiration, the goal of glycolysis is to produce a little bit of ATP, as well as generating NADH to restart the process and continue making small amounts of ATP. The process is started with a molecule of glucose, and at the end we are left with 2 molecules of ATP, 2 of NADH and 2 of a molecule known as pyruvate. So, let's take a deeper look into the steps and energy transfers in glycolysis

Segment 2: More About Steps of Glycolysis and Energy Transfers

The starting molecule of glucose enters the cytoplasm of the cell, and is rearranged into 2 3-carbon sugars with phosphate groups attached. These phosphate groups come from two molecules of ATP splitting into ADP and P. From there, both of these 3-carbon sugars are oxidized, meaning they lose their electrons. These electrons go to molecules of NAD+, and reduce them to NADH. This is an oxidation-reduction reaction, since the molecules of glucose leave and go to NAD+, so glucose is oxidized and once again NAD+ is reduced to NADH. What's left of the oxidized glucose is now our key 3-carbon molecule of pyruvate. Through the reactions oxidizing the 3-carbon sugars of glucose into pyruvate, we have made 2 molecules of ATP and 1 of NADH. However, we must remember that there are 2 molecules of pyruvate that were made, meaning we have a total yield of 4 ATP and 2 NADH. And since we used up two molecules of ATP to get our phosphate groups in the beginning, we have a net yield of only 2 ATP.

Throughout the process of glycolysis, and really all of cellular respiration we are focused on oxidizing and breaking down glucose. This means we are breaking chemical bonds, which we know releases energy. Therefore, glycolysis is an exergonic process.

Segment 3: Connection to the Course

Glycolysis has many important connections to our unit of cellular energetics and our ap biology course overall. First, we remembered OILRIG and oxidation-reduction reactions when dealing with glucose and NAD+/NADH. We also talked about how glycolysis is an exergonic process, since the breaking of bonds releases energy. This means that the delta G of the process is negative.

Additionally, glycolysis occurs in all organisms, whether they are in anaerobic or aerobic conditions. Glycolysis is part of anaerobic respiration for organisms to produce a small amount of ATP as energy and keep regenerating NADH, but for more information on anaerobic respiration listen to episode #76.

Lastly, we can connect topics of enzymes to the process of glycolysis. Each step in the process of glycolysis has a specific enzyme to catalyze it, the most important one being phosphofructokinase. We can apply our knowledge of enzyme activity here, to know that increasing or decreasing factors like pH and temperature can speed up or slow down the rate of the reaction, since they affect the enzyme's ability to lower activation energy.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Cellular Respiration: An Overview

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode #71 called Unit 3 Cellular Energetics: Cellular Respiration:An overview. Today we will be discussing what cellular respiration is,who uses it, and why it's important.

Segment 1: Introduction to Cellular Respiration

All organisms perform cellular respiration. The reactants of cellular respiration are glucose, which is oxidized, and oxygen which is reduced and they both produce carbon dioxide, water, and ATP. The purpose of cellular respiration is to make energy for cell work in the form of ATP. This occurs in a series of metabolic reactions. The reactions involved are catabolic reactions, which break down large molecules into smaller ones, releasing energy in the process which is supported by the overall reactions negative delta G. The ATP produced is eventually recycled and used to make more ATP. Most of the energy is released when reduced molecules are fully oxidized to create CO2. The oxidation occurs in a series of small steps allowing the cell to harvest 34% of the energy released. The rest of the energy is lost as heat.

Segment 2: More About Cellular Respiration

The two types of cellular respiration are anaerobic and aerobic. Anaerobic respiration can occur without oxygen while aerobic respiration requires oxygen to be present. Anaerobic respiration does not release enough energy to power human cells for long. It primarily occurs in muscle cells during hard exercise, after the oxygen has been used up. It also occurs in yeast during fermentation. Many prokaryotes perform anaerobic respiration.Through Anaerobic respiration, glucose is broken down to form 2 pyruvates. The purpose is to regenerate NAD plus for glycolysis, which is a part of aerobic respiration. Anaerobic respiration also keeps the pyruvate produced in the cytoplasm and uses it there. The main reactants are glucose, ADP, and Pi. This then produces ethanol, carbon dioxide and 2 atp. Anaerobic respiration has different products in animals. In animals instead of ethanol being produced, lactic acid is produced.
Aerobic respiration has 4 steps, glycolysis, pyruvate oxidation, the krebs cycle also known as the citric acid cycle, and the electron transport system. Glycolysis occurs in the cytoplasm, pyruvate oxidation and the citric acid cycle occur in the mitochondrial matrix, and the electron transport system occurs in the cristae of the mitochondria. In glycolysis, glucose is converted to pyruvate, ATP is produced, and NADH is produced. The energy transfers include 2 ATP used to produce 4 ATP ,NAD+ being reduced, Glucose being oxidized, and energy lost as heat. Overall, 2 net ATP are produced and no oxygen is used. Next, in pyruvate oxidation, Pyruvate is oxidized which reduces NAD+ to NADH. Coenzyme A reacts with the decarboxylated pyruvate to create acetyl CoA. This process occurs two times per glucose molecule. Again, energy is lost as heat is released. This time, CO2 is produced as a waste product. In the citric acid cycle, Acetyl CoA reacts with oxaloacetic acid to form citric acid . Citrate gets oxidized and loses carbons in the form of CO2. In that process, NAD+ and FAD are reduced into NADH and FADH2. Oxaloacetate is also regenerated since the process is a cycle. ADP+Pi makes ATP and total of 2 ATP is produced. Acetyl COA from the pyruvate oxidation and Pyruvate is needed for the reaction and CO2 is produced and heat is released. Lastly, in the electron transport system, Cells transfer energy from NADH and FADH2 to ATP by oxidative phosphorylation. NADH oxidation is used to actively transport H plus across the inner mitochondrial membrane, resulting in a proton gradient. Electrons from the oxidation of NADH and FADH2 pass from one carrier to the next in the chain. The oxidation reactions are exergonic and the energy released is used to actively transport H+ ions across the membrane.This Diffusion of protons back across the membrane then drives the synthesis of ATP. There is the potential to make 34 molecules of ATP from the electron transport chain but the number in real life is closer to 29. The entire process of aerobic cellular respiration has the potential to produce 36 ATP while anaerobic respiration alone can only produce 2 ATP per glucose molecule.

Segment 3: Connection to the Course

The process of cellular respiration has many connections to AP Biology in general. Cellular respiration is essential to produce ATP which is used by cells to power their metabolism and all their activities. The energy stored in food is broken down into a usable form. Cellular respiration can also connect to the theory of evolution and the theory that all organism evolved from a common ancestor. The fact that all living organisms perform anaerobic cellular respiration also supports this hypothesis because the common ancestor most likely performed anaerobic respiration meaning aerobic respiration evolved later since only some organisms can perform aerobic respiration.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Oxidation and Reduction

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Victoria Villagran and I am your host for episode # 70 called Unit 3 Cellular Energetics: Oxidation and Reduction. Today we will be discussing Oxidation and Reduction

Segment 1: Introduction to Oxidation and Reduction

They are redox reactions, a type of chemical reaction that involves a transfer of electrons between two species, and are vital to the basic functions of life, including photosynthesis
Specifically, an oxidation-reduction reaction is any chemical reaction in which the oxidation number of a molecule, atom, or ion changes by gaining or losing an electron. Energy can also be transferred by the transfer of electrons in reduction-oxidation
Reduction is the gain of one or more electrons; endergonic reactions
Oxidation is the loss of one or more electrons; exergonic reactions
They always happen together
The more reduced a molecules is, the more energy is stored in its bonds
OIL RIG (Oxidation Is Loss; Reduction Is Gain)

Segment 2: More About Oxidation and Reduction in Cellular Respiration

Cellular Respiration: glucose is oxidized and oxygen is reduced and
Only looking at where molecules are being either reduced or oxidized
Glycolysis
Glucose is being slowly oxidized as it is being converted into pyruvate, and then that electron is added to NAD+, reducing NAD+, converting it to NADH.
This produce 4 ATP, 2 Pyruvates, and 2 NADH from 2 ATP, 2 NADH+, and Glucose
The energy in oxidizing glucose or lost from it was lost as heat
Pyruvate Oxidation
Pyruvate is oxidized (removing electrons) which then that electron reduced NAD+ to NADH, connecting glycolysis to the citric acid cycle
This produces NADH, Acetyl CoA, CO2 from Pyruvate and Coenzyme A, and energy is released from the oxidation reaction and lost as heat
Citric Acid Cycle
Acetyl CoA (2C) reacts with oxaloacetic acid (4C) to form citric acid (6C); citrate gets oxidized and loses carbons in the form of CO2. In that process, NAD+ and FAD are reduced into NADH and FADH2. Oxaloacetate is regenerated.
The acetyl group is what is left of the glucose and is broken down (metabolized) in the citric acid cycle
Summary: Gaining electron carriers while oxidizing the carbon molecules or stripping away electrons like glycolysis
To sump it up, NAD = to NADH (reduction), FAD is reduced to FADH2
Citrate is oxidized in many steps
Electron Transport Chain/ ATP Synthesis
Electron transport: electrons from the oxidation of NADH and FADH2 pass from one carrier to the net in the chain. The oxidation reactions are exergonic, energy released is used to actively transport H+ions across the membrane
Cells transfer energy from NADH and FADH2 to ATP by oxidative phosphorylation:
NADH oxidation is used to actively transport protons (H+) across the mitochondrial membrane, resulting in a proton gradient
Diffusion of protons back across the membrane then drives the synthesis of ATP

Segment 3: Connection to the Course of Cell Energetics

Due to oxidation and reduction reactions, cells can use organic and inorganic molecules to create or transfer energy to power the cell, through specific processes such as cellular respiration and photosynthesis, and the synthesis of ATP. Where these molecules are either losing or gaining electrons, and the heat released or absorbed are lost as heat or used to power the step in the process to provide energy for the cell. Which then leads to the bonds in ATP being broken and are strong enough to power different cellular processes or the cell’s metabolism.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. Have a nice day!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

ATP Structure, Synthesis, and Hydrolysis

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Arthur Kim and I am your host for episode # called Unit 3 Cellular Energetics: ATP Structure, Synthesis, and Hydrolysis. Today we will be discussing the structure of ATP as well as the processes under which it is formed and broken down.

Segment 1: Introduction to ATP Structure, Synthesis, and Hydrolysis

ATP is basically the energy currency that our cells use in order to carry out their essential functions.
It is comprised of the nitrogenous base adenine bonded to a ribose sugar, attached to which are three linked inorganic phosphate groups.
The reason why ATP is the energy currency is that a lot of energy is released when the bond between the last two phosphate groups is broken, specifically -57kJ/mol.

Segment 2: More About ATP Structure, Synthesis, and Hydrolysis

ATP is synthesized through the phosphorylation, the adding of an inorganic phosphate group, of ADP.
Happens in two instances.
The phosphorylation of ADP into ATP is a part of glycolysis, and overall, a net 2 ATP is produced.
Synthesized by the enzyme, ATP synthase, which phosphorylates ADP into ATP when protons pass through it via chemiosmosis.
This means of synthesizing ATP is an essential aspect of both cellular respiration and photosynthesis.
The proton gradient that allows ATP synthase to work is generated by the ETC.
Conversely, ATP is hydrolyzed by means of dephosphorylation, where the inorganic phosphate group at the end of the chain is broken off after the ATP molecule reacts with a water molecule.
As stated previously, this process is exothermic, providing the activation energy needed to carry out countless essential biochemical reactions.

Segment 3: Connection to the Course

Being the main energy currency, ATP is a cornerstone for the function of almost all life on Earth.
As all biochemical reactions have an activation energy requirement to proceed, the hydrolysis of ATP is absolutely essential.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Metabolic Pathways & Coupled Reactions in Living Organisms

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Alex Jing and I am your host for episode 68 called Unit 3 Cellular Energetics: Metabolic Pathways & Coupled Reactions in Living Organisms . Today we will be discussing the purpose of metabolic pathways and coupled reactions in living organisms

Segment 1: Introduction to Metabolic Pathways & Coupled Reactions in Living Organisms

Metabolism encompasses all reactions that happen within cells
Series of reactions are organized into metabolic pathways
These reactions are catalyzed by enzymes, and are either
Catabolic, which breaks down molecules through hydrolysis, or
Anabolic, which builds molecules using dehydration synthesis
Coupled reactions are reactions that are paired together, where one reaction usually releases energy and the other reaction requires energy
Catabolic reactions are coupled with anabolic reactions so that the energy released by the catabolic reaction is used for the anabolic reaction

Segment 2: More About Metabolic Pathways & Coupled Reactions in Living Organisms

An example of a metabolic pathway is the calvin cycle, which sends pyruvates into a series of reactions to product NADH and FADH, both of which are used to produce ATP.
This is done by continuously reducing the pyruvate to provide electrons for NAD+ and FAD+ to reduce to NADH and FADH
This allows the body to continuously break down pyruvates in a cyclic fashion to produce NADH and FADH to produce ATP.
An example of coupled reactions in the body is how cells use ATP. Many processes like active ion transport, muscle contraction, and chemical synthesis, are not spontaneous. The body uses ATP to provide the energy for these reactions to proceed by coupling the reactions with the decomposition ATP, using the energy released to fuel the reaction.

Segment 3: Connection to the Course

Metabolic pathways and coupled reactions are extremely important to biology. Metabolic pathways allow organisms to manipulate molecules that they consumed into molecules that the body can regularly use
Coupled reactions allow the body to transfer the energy used in an exergonic reaction to power a reaction that uses the energy released.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (Enter your closing Tag-line)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Endergonic and Exergonic Reactions

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #67 called Unit 3 Cellular Energetics: endergonic and exergonic rxn. Today we will be discussing the differences between endergonic and exergonic reactions and how they play a role in metabolic processes.

Segment 1: Introduction to endergonic and exergonic rxn

● Exergonic

○ Release energy

○ Products have less free E than reactants

○ Energetically downhill

○ Tend to be spontaneous

○ Tend to be catabolic aka break down rxn

○ Delta G is neg

■ Remember delta g is free energy aka usable energy

● Endergonic

○ Absorb energy

○ Products have more free E than reactants

○ Energetically uphill

○ Tend to not be spontaneous

○ Tend to be anabolic aka create

○ Delta G is pos

Segment 2: More About endergonic and exergonic rxn

● Example of endergonic rxn

○ Dehydration synthesis

○ Combining molecules

○ Release water

○ Take in energy

● Example of exergonic rxn

○ Hydrolysis of ATP

○ Breaking apart molecules

○ Water molecule is taken in

○ More energy out of system

○ Releases energy

Segment 3: Connection to the Course

● There is a series of intermediate reactions that form a metabolic pathway

● While enzymes play a role in these reactions, an important concept that connects exergonic and

endergonic reactions is coupled reactions

○ This is when a catabolic reaction that breaks down something is coupled with a reaction that

makes something

○ Let's remember that endergonic reactions are usually anabolic exergonic reactions are usually

catabolic

● So in the case of ATP hydrolysis, E is released by the exergonic rxn because remember the bonds are

being broken so E is released and this energy can now go and drive an endergonic reaction

● This coupling of reactions plays a big role in the intermediate reactions that form metabolic pathways

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

● "Ice Flow" Kevin MacLeod (incompetech.com)

● Licensed under Creative Commons: By Attribution 4.0 License

● http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Laws of Thermodynamics

Hopewell Valley Student Publications Network — Mon, 24 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode # 66 called Unit 3 Cellular Energetics: The Laws of Thermodynamics. Today we will be discussing the three laws of thermodynamics.

Segment 1: Introduction to the Laws of Thermodynamics

I’ll start by listing the three laws of thermodynamics, and then I’ll explain each one conceptually. The first law of thermodynamics states that energy is always conserved, and can never be created or destroyed. The second law states that the sum of the entropy of a system and its surroundings must always increase. Lastly, the third law states that a perfect crystalline solid at absolute zero has an entropy of zero.

Segment 2: More About the Laws of Thermodynamics

Now let’s dig deeper into each law. As I stated, the first law of thermodynamics is about conservation of energy. Rather than being destroyed, energy in the system is converted to other forms of energy. For example in a swinging pendulum, energy is converted from potential energy to kinetic energy as it swings. In each swing, a small amount of energy is transferred to heat due to friction with the air. This eventually causes the pendulum to stop. As you can see, there is no energy destroyed in this system. Energy goes from potential to kinetic until all of the energy gets transferred to heat.
The second law of thermodynamics is about entropy in a system. Entropy is most easily described as disorder. So, when we say entropy is always increasing, what this means in the most basic sense is that disorder of the universe or a system is always increasing. An analogy for this is a bedroom. As time goes on, your bedroom will become more and more messy if you don’t clean it. However, your bedroom will not become more and more neat. This is similar to entropy because energy in a system has a tendency to become more disordered or dispersed, just like your bedroom has a tendency to become more disordered.
The third law of thermodynamics has to do with absolute zero. Absolute zero is conceptually the coldest possible temperature. Temperature is described as a measure of available heat energy. As the temperature goes down in a system, the kinetic energy of particles drops as well. If the temperature drops enough, then the kinetic energy of particles completely runs out and the particles come to a stop. This is called absolute zero. At this temperature, any substance becomes solid. This means that the entropy of the substance at absolute zero will be zero. Since no particles are moving, there is only one possible state for a substance to be in. Basically, there is no disorder, meaning there is no entropy. However, it should be stated that absolute zero is impossible to reach.

Segment 3: Connection to the Course

These laws that govern large systems are also what govern metabolic pathways like cellular respiration and photosynthesis. When we talk about the reactions happening in our metabolic pathways, we’ll often state that energy is lost. This relates back to the first law of thermodynamics. When we say that, we don’t really mean that energy is lost. What we really mean is energy is lost as heat. When we look at photosynthesis and cellular respiration, we can track where the energy is being transferred.
When we lose energy as heat in each reaction during photosynthesis or cellular respiration, we are really increasing the entropy of the system. This relates directly to the second law of thermodynamics which states entropy in a system has a tendency to increase.
The third law of thermodynamics doesn’t relate much to what we have learned in this course so far, but it’s important to understand it so that we can further understand how entropy and absolute zero work.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com.

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Enzyme Activators and Inhibitors

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 3 Cellular Energetics

Welcome to My AP Biology Thoughts podcast, my name is Chloe McGregor and I am your host for episode #65 called Unit 3 Cellular Energetics: Enzyme activators and inhibitors. Today we will be discussing the role of activators and inhibitors in enzyme activity.

Segment 1: Introduction to activators and inhibitors

It is important to understand the enzyme substrate complex first. Substrates and Enzymes are extremely specific to one another regarding the shape and charge of the site at which they bond. This site is called the active site. Each different substrate utilizes a specific enzyme, and is broken down from there. However, enzyme activity can be altered by both inhibitors and activators. More specifically, inhibitors are often disadvantageous as they decrease the rate at which the enzyme can work. On the other hand, activators work in order to turn enzymes back on so they can work. There are so many processes going on in the body which are not all happening at the same time. Because of this, enzymes are often deactivated, and not at work. This is why activators are so important because they activate the enzyme in order for it to function again.

Segment 2: More About Enzyme activators and inhibitors

To go more in depth, there are 2 types of enzyme inhibitors. Competitive inhibitors attach to the active site of the enzyme which prevents the substrate from binding to the enzyme. This is known as competitive inhibition because the substrate is competing with the inhibitor for the active site. To combat this, you can increase the substrate concentration in order to ultimately outcompete the inhibitors. Another type of inhibitor is the noncompetitive inhibitor. This is when it attaches to a different site on the enzyme causing the enzyme to change shape which prevents any substrate from binding at all. Another word for this is allosteric regulation. This inhibition can not be combatted because the enzyme changes shape, so increasing the substrate concentration would have no impact at all. In addition to these common inhibitors, feedback inhibition is when the final product of a reaction acts as an inhibitor to the first enzyme. This shuts down the pathway, and can be done either competitively or noncompetitively. There are also two branches of activators. Allosteric activation is when a new molecule binds to a different site on the enzyme to open the active site back up. Phosphorylation, on the other hand, happens when the existing protein structure is chemically modified. An example of this can be shifting a hydrophobic region to a hydrophilic region to allow certain reactions to occur. Phosphorylation also opens back up the active site similar to allosteric activation, however there is no outside molecule.

Segment 3: Connection to the Course

Inhibitors and activators are important in the greater scheme of things. In terms of cell energetics, both cellular respiration and photosynthesis are metabolic pathways. This means that there are a ton of tiny steps involved each utilizing different enzymes. In terms of activators, it is important that enzymes are activated and ready to catalyze a reaction when it is time. Oxidative phosphorylation is a great example of enzyme activation which is so crucial in order to make a sufficient amount of ATP. In terms of inhibitors, they are important for regulating metabolic pathways. Inhibitors can be beneficial as they stop the overproduction of products when there is no need for them. This is evident in the glycolytic pathway through allosteric regulation. Protein structure is also also crucial to the way a cell does work, so inhibiting an enzyme can cause a domino effect as the tertiary and quaternary structures begin to unfold. Overall, activators and inhibitors are important factors when studying enzyme activity, and it is important to understand their effects on the catalysis of different reactions.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. (Enter your closing Tag-line)!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Apoptosis

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #64 called Unit 2 Cell Structure and Function: Why Apoptosis?

Segment 1: Introduction to Apoptosis

Apoptosis is when a cell undergoes a programmed death. This is different from necrosis which is when cells die from injuries. Apoptosis is the most convenient way for an organism to remove cells that need to be removed.

Segment 2: More About Apoptosis

In apoptosis a cell commits suicide for a variety of reasons. One reason could be because some cells need to be removed in order to shape a structure. For most organisms, especially those with hands and feet, apoptosis is necessary for proper growth and development. For organisms with hands and feet, the hands and feet start off as a block of tissue that needs to have some cells removed so it can take a shape where it can be useful. To the organism. An example of this comes from the human hand. Hands are formed from larger blocks of tissue. Some parts of this larger block need to be removed so the block of tissue can take the structure of a hand. The cells that need to be removed go through apoptosis. This process also happens on other structures like the tails of tadpoles. Another reason why cells may need to go through apoptosis is because they are damaged or infected. If the DNA in a cell is damaged, this could potentially negatively affect the entire organism. Because of this the cell will go through apoptosis to ensure it won’t do any damage to the organism. Another way the cell could be damaged is by viral infections. If a virus has infected a cell, the cell will undergo apoptosis. Apoptosis also happens when cells need to be taken away to maintain balance, or if the cell was somewhere for a temporary task and is no longer needed.

What happens to a cell that undergoes apoptosis? They start off by shrinking while bubble-like structures form around the surface of the membrane. The DNA as well as organelles then get cut into smaller pieces. These pieces end up trapped in membranes which then signal phagocytic cells to come to them. What’s different about the membranes, that the pieces are enclosed in, is that there is a lipid called phosphatidylserine (fosfa-tidal-serine) that’s on the surface when it’s usually on the inside of the membrane. This lipid allows the phagocytic cells to envelop them.

Another reason that apoptosis is important is because it helps prevent cancerous, infected cells or damaged cells from damaging the organism by killing those cells before they can do any harm. When a cell’s DNA is damaged, it can go through repairs to fix it, but these repairs can only go so far. If the DNA is damaged to the point where it cannot be repaired, the cell undergoes apoptosis. Now on to cancerous cells. Before cells become cancerous, they normally use internal apoptosis cues which allows them to die off before any harm is done. Sometimes though, the cancerous cells can avoid the internal apoptosis cue and will not die. If this happens, then immune cells can detect them and force the cell to go through apoptosis through an external cue. If a cancerous cell is somehow able to avoid both the cues, then it will be able to divide and mutate which could be harmful or fatal to the organism.

Segment 3: Connection to the Course

Apoptosis is one of the most important processes in cells. Without it, an organism's development would become abnormal and they would likely die from a viral infection or cancer. Just like photosynthesis or the krebs cycle, apoptosis is a process that is essential to an organism and its cells. Apoptosis is something that is important to the survival of many different organisms that aren’t even closely related. The fact that apoptosis is used in so many different organisms can even be used as proof of evolution.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Water Potential

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode #63 called Unit 2 Cell Structure and Function: Water Potential. Today we will be discussing the basics of water potential in relation to cells.

Segment 1: Introduction to Water Potential

There is a common misconception in differentiating osmosis and water potential. Osmosis is the movement of water through the semipermeable membrane. Water potential is the potential energy of water per unit area compared to pure water, so in simpler terms it allows us to figure out where water is going to flow. Water will always flow from high to low water potential. There are two equations to calculate it. First, water potential is equal to the solute potential plus the pressure potential. The solute potential is a factor of osmosis, while the pressure potential is a factor of pressure on a cell wall. The second equation comes into play to calculate the solute potential. The equation is -iCRT, where i is the ionization constant, C is the molar concentration, R is the pressure constant, and T is temperature in kelvin degrees. The units are bars.

Segment 2: More About Water Potential

Most of the water potential problems you will be presented with will be straightforward algebra to plug into the solute potential equation to then determine the net flow of the water. For example, it is given that a cell’s pressure potential is 3 bars and the solute potential is -4.5 bars. The cell is placed in an open beaker of sugar water with a solute potential of -4 bars and you are asked to determine the net flow of the water. You would find the cell’s water potential by adding 3 and -4.5 bars to get -1.5 bars, which is greater than the water potential of the sugar water, so the water will flow out of the cell. A key takeaway from this example is that pressure potential in an open beaker will always be zero. Another example could give you the same information, but the cell was placed in an NaCl solution instead, which therefore changes the ionization constant to 2 because there are now 2 ions in the solution. Lastly, the most complex example would involve cubes of vegetables like potatoes or zucchini to be placed in sucrose solutions with different concentrations. The percent change in mass of each cube would be calculated after the experiment held at a constant temperature. It will ask you to calculate the water potential of the cubes. The best way to come around these problems is to graph the sucrose concentrations versus the percent change of mass. This will result in a linear relationship, where the x-intercept represents the cell in an isotonic state when equal amounts of water are leaving and entering. So you would then plug in the value of the concentration at the x-intercept into the iCRT equation and go from there.

Segment 3: Connection to the Course

Water potential is a concept to have mastered because it explains the most basic observations. It explains why humans cannot drink salt water because since seawater has a lower water potential than our cells, drinking it will only cause water to flow out of our cells and into the seawater. This ultimately will kill our cells because they will shrivel up and shrink, which reduces your chances of survival. On the other hand, it also explains why red blood cells cannot be found in distilled water. The water would go into the more hypertonic red blood cell causing it to swell and then burst. Overall, water potential explains the results of isotonic, hypertonic, and hypotonic solutions all due to osmosis.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Osmotic Pressure of Plant Cells

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Arthur Kim and I am your host for episode #62 called Unit 2 Cell Structure and Function: Osmotic Pressure of Plant Cells. Today we will be discussing osmosis and turgor pressure in plant cells and their effects.

Segment 1: Introduction to osmotic pressure of plant cells.

Osmotic and Turgor pressure are what allow plant cells to maintain their shape and form.
Key terms:
Osmotic Pressure: Pressure on the cell from the inside out as a result of water entering the cell via osmosis.
Turgor pressure: The pressure of the cell membrane pressing against the cell wall as a result of the cell being full of water.
Plasmolysis: A plant cell collapsing as a result of losing too much water.
Isotonic solution: When there’s an equal concentration of solute on both sides of a membrane.
Hypotonic solution: When the concentration of solutes inside the cell is greater than on the outside.
Hypertonic solution: When the concentration of solutes outside the cell is greater than on the inside.

Segment 2: More About Osmotic Pressure of plant cells

The rigidity of the cell wall allows plant cells to survive in both isotonic and hypotonic solutions.
In hypotonic solutions, the excess water results in Turgor pressure against the cell wall, but the cell wall does not give.
This enables the plant cell to become extremely rigid, giving the plant its structure.
In hypertonic solutions however, plant cells would lose water and therefore plasmolyze, killing the cells.
Turgor pressure from osmosis prevents the cell from collapsing in on itself.

Segment 3: Connection to the Course

The fact that cell walls are able to withhold Turgor pressure allows plant cells to store excess amounts of water. This poses a major evolutionary advantage because the plants that can survive through droughts will more likely produce offspring.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Osmotic Pressure of Animal Cells

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode #61 called Unit 2 Cell Structure and Function: Osmotic Pressure of Animal Cells. Today we will be discussing _the osmotic pressure of animal cells.

Segment 1: Introduction to Osmotic Pressure

What is osmosis?
The movement of a solvent/water through a semipermeable membrane from a low concentration or high water potential, where there is less solute to a higher concentration or low water potential, and it’s goal is to reach equilibrium of equal concentration of solute on the inside and out of the membrane/cell
an example of passive transports as it does not require energy
What is osmotic pressure?
Osmosis creates pressure
The pressure that must be applied to the solution side to stop fluid movement when a semipermeable membrane separates a solution from pure water.
the pressure that would be required to stop water from diffusing through a barrier by osmosis. In other words, it refers to how hard the water would “push” to get through the barrier in order to diffuse to the other side.
Determined by solute concentration, water will “try harder” to diffuse into an area with a high concentration of a solute, such as a salt, than into an area with a low concentration.

Segment 2: More About Osmotic Pressure of Animal Cells

Water moves to hypertonic areas
It can threaten the health of cells and organisms when there is too much or too little water in the extracellular environment compared to the inside of the cell.
Animal cells lack a cell wall, and use active transport systems (especially the NA+ K+ ATPase that moves 3 NA+ out for each 2 K+ that move in) to move ions outside the cell reducing the osmotic pressure.
Most protozoa use a special contractile mechanism. Water collects in a vesicle, and microfilaments force a contraction that squeezes water back outside the cell. This pump mechanism protects the cell from osmotic pressure

Segment 3: Connection to the Course

How does the osmotic pressure of animals connect back to cell structure and function?
Without osmotic pressure the animal cells would not be able to move solvent/water through a semipermeable membrane from a low concentration to high concentration, and not reach equilibrium of equal concentration of solute on the inside and out of the membrane/cell
This will collapse its structure and both will then lead the cell to death unable to perform its necessary functions
It is vital as the cell’s membrane is selective toward many of the solutes found in living organisms
It determines the state/survival of the cell as well, like when it is placed in a hypotonic, isotonic, or hypertonic solutions

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Isotonic, Hypertonic, and Hypotonic Conditions

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode #60 called Unit 2 Cell Structure and Function: Isotonic, Hypotonic, and Hypertonic Conditions. Today we will be discussing the differences between these conditions

Isotonic, hypertonic, and hypotonic are all words to describe the conditions of a cell in relation to the amount of solute and water in them. An isotonic condition is when the concentration of water is the same inside and outside of the cell. This creates an equilibrium, so there will be no large movement of water in or out of the cell. However, an isotonic solution does allow for osmosis, but the rate of water moving in and out of the cell will always be the same. If a cell is in a hypertonic solution, water will flow out of the cell because there is a higher concentration of solute outside of the cell. This causes water to flow out of the cell because the concentration of water is lower outside of the cell, water will flow out of the cell to try to create an equilibrium. The word hypertonic comes from the Latin prefix hyper, which means above. In a hypertonic solution, a cell will shrink. If a cell is placed in a hypotonic solution, there is net flow of water into the cell because the solute concentration outside the cell is lower than inside the cell. Because of this, the water concentration inside the cell is lower than outside the cell, causing water to flow into the cell and the cell to expand.

Plant and animal cells can thrive in different conditions because of their different characteristics. For example, red blood cells find isotonic solutions ideal because they maintain constant conditions. However, in plants, an isotonic solution will cause the pressure in the cells to decrease, and the plant will appear to wilt. In hypertonic solutions, neither plant nor animal cells thrive. In red blood cells, hypertonic solutions will cause the cells to shrivel and possibly die. In plant cells, hypertonic solutions will cause the plant to wilt because water leaves the cells. In order to avoid hypertonic situations, one can make sure that the plant or animal is properly hydrated. For animal cells, hypotonic solutions are harmful, and red blood cells may burst because the net flow of water is into the cell. However, hypotonic solutions are ideal for plant cells, because their cell walls don’t allow them to burst. In hypotonic conditions, plant cells become slightly enlarged but this is beneficial as it allows the plants to be more rigid and not wilt. Hypotonic solutions in plants can be caused by regular watering.

Isotonic, hypertonic and hypotonic conditions are all very different, but they all indicate the health of the organism. The difference in reactions by plant and animal cells to these conditions show the different structures of plant and animal cells. Because plant cells have cell walls, they are able to thrive in hypotonic conditions whereas animal cells will likely die. However, these different structures enable their respective organisms to live, as we saw with plants and hypotonic solutions, which keep them from wilting. This shows that each type of cell has evolved to be able to best keep its organism alive.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Active Transport: Endocytosis, Exocytosis, and Protein Pumps

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Morgan Bernstein and I am your host for episode #59 Unit 2: Active Transport: Endocytosis, Exocytosis, and Protein Pumps.

Segment 1: Introduction to Active Transport

First, we have to know that within any cell, things are always moving. Proteins need to get places, waste has to be excreted, and food is consumed.

Two umbrella terms of movement- Passive Transport and Active Transport
Passive Transport=no energy required, almost like a habit
Active transport = within a vesicle, does require energy

Active transport is what we will be discussing in this episode, but be sure to check out episode 58 to learn about passive transport as well!

Why does active transport require energy?

Goes against the concentration gradient
Things are moving from low concentration to high concentration (disrupts equilibrium and requires extra energy)
Can happen across a cell membrane or within the cell itself

Segment 2: Examples of Active Transport: Endo/Exocytosis and Pumps

The first type of active transport is one that does cross a cell-membrane barrier, and it is known as the sodium-potassium pump.

Two potassium ions into the cell and takes three sodium ions out
Works because of the protein pump in the plasma membrane.
Three sodium ions bind to the carrier protein pump inside the cell, and are transported out using the energy available from ATP.
Protein then changes shape to allow for the potassium ions to bind to it as well, and pumps those inside of the cell membrane where they are transported for use in the cell before the process repeats.
Higher concentration of potassium ions inside the cell than outside, and a higher concentration of sodium ions outside the cell, so this sodium-potassium pump is going against the concentration gradient and is therefore a form of ACTIVE transport
Requires energy.

Another form of active transport comes in endocytosis and exocytosis

First, cytosis means cell, which is present in all three terms
Endo = enter, + cytosis = cell, so endocytosis = into the cell
Exo = exit, + cytosis = cell, so exocytosis = exiting the cell.

Endocytosis

Things brought into the cell across the membrane, but not through a pump
Requires energy
Happens inside a vesicle (small cellular bubble that holds and transports other molecules and ions)
Molecules or ions outside of the cell are enclosed by a part of the plasma membrane, forming the vesicle, and vesicle brings the contents through the membrane into the cell for transport

Exocytosis

export proteins or excrete waste products
Requires energy

Necessary protein or waste products inside of a transport vesicle, vesicle connects with plasma membrane and contents released into outside environment.

Segment 3: Connection to the Course

Active transport has many connections to our Unit 2 about Cells and to biology in general.

Goes against the rules used for any other cellular movement ex. osmosis or diffusion.
Usually moving from high concentrated areas to low concentrated areas, active transport is OPPOSITE and requires energy.

These processes are all due to the selective permeability of the plasma membrane of cells.

Membrane structure of phospholipids and proteins (w/0 = everything or nothing would be able to enter and exit a cell)
No active transport without transport vesicles and protein pumps
Potassium is charged- could not enter phospholipid bilayer
Important to remember the characteristics and functions of the cell membrane and organelles when studying types of cellular movement such as active transport.

We can also connect active transport to the most basic of everyday activities; eating and drinking

phagocytosis and pinocytosis- cellular eating and cellular drinking
Without this, cells would be unable to get essential nutrients needed to function (humans hungry/dehydrated)

Lastly, I want to touch on one more type of cellular transport that requires energy, which is transcytosis. movement across a cell, also takes place in a vesicle

Transport vesicles move proteins to various regions of the cell to perform necessary processes

Connects to central dogma through the making of proteins (ribosomes to Endoplasmic Reticulum and Golgi Apparatus, DNA translation, RNA transcription, protein synthesis)

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Passive Transport: Diffusion, Osmosis, and Facilitated Diffusion

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Jacky and I am your host for episode #4 called Unit 2 Cell Structure and Function: Passive Transport. Today we will be discussing the different types of Passive Transport which are Simple Diffusion, Osmosis, and Facilitated Diffusion.

Segment 1: Introduction to Passive Transport.

For cells to survive, they must take in or expel certain particles and substances. What monitors their entry or exit is the plasma membrane in a process known as membrane transport.
Two types of transport: active and passive.
Active requires atp energy, cell is purposely doing it
But today focusing on passive transport, where no energy is required to move materials in or out, natural process known as diffusion
3 main types: Simple diffusion, osmosis, and facilitated diffusion
In all types, movement is based on a concentration gradient, substances move from areas of high conc. To low, whether this is in or out of cell
Seeking equilibrium, a balance in concentration

Segment 2: More About Passive Transport

Start with simple diffusion
The movement of particles down the concentration gradient across the semipermeable lipid membrane.
If there is a greater concentration of a particle on one side of the membrane, simple diffusion will occur and the particle will move to the area of lower concentration.
These particles must be small and non-polar, as only these types of particles can make their way through the lipid membrane.
For example CO2 and O2, CO2 is often produced and of high conc. Within cells so it will diffuse outwards. O2 is often present in higher conc. Out of cell, so it will typically diffuse inwards.
A useful analogy would be to think about the smell of cooking wafting through the house. When you cook, the food molecules are highly concentrated in the air around the stove, so the smell is strongest around there. However, the food molecules will soon diffuse throughout the house into areas of lower concentration, which is why the smell of the food will eventually reach you in a different room.
Osmosis: A type of simple diffusion except with water as the specific particle diffusing
Specifically, movement of water molecules down the concentration gradient across semipermeable lipid membrane
Water in an area with higher conc. Of water vs solute Will diffuse into an area with lower conc of water. Vs solute
For example...
If placed in a hypertonic solution, where the concentration of solutes is higher than the cell, water will flow out of the cell and into the solution to balance out the lower conc. Of water outside
If placed in a hypotonic solution, where conc. Of solutes are lower than the cell, water will flow into the cell to balance out the lower conc. Of water in it
Osmosis’s ultimate goal however is to create an isotonic environment, where the concentration of solute and water is equal inside and outside of the cell. In this case, water will still be flowing in and out, and cells will be able to function normally.
Facilitated diffusion
Sometimes simple diffusion will not work, as certain particles are blocked by the semi-permeable cell membrane whether due to size or polarity
Cell still needs these particles, so they must find another way to get them: this way is facilitated diffusion
Facilitated diffusion occurs with the help of specialized proteins called channel proteins and carrier proteins. These proteins provide a larger opening for needed molecules to pass through passively.
Channel proteins are not specialized for certain molecules, and will like the cell membrane discriminate based on size (only for channel proteins, size allowance is larger)
Often carry across ions
An example of channel protein is an aquaporin, designed for quick transport of water, quicker than the time needed to cross cell membrane
Carrier proteins are often more specialized, usually taking in only one specific type of molecule, and undergo a specific process when transporting the molecule]
The carrier channel will mold itself to the shape of the particle before guiding it into or out of the cell
This is why it is so selective, as different molecules have distinct shapes that specialized carrier proteins may not accept
An example of a molecule transported by carrier proteins is glucose. Glucose is a large polar molecule that cannot undergo simple diffusion, so it must be specifically move into the cell by a carrier protein

Segment 3: Connection to the Course

Passive transport and its 3 types are important for many reasons
Most significantly, bring in particles/molecules vital to the survival of the cell, such as water and sugars
Works in tandem with active transport. Cell cannot wastefully expend ATP on bringing in every type of molecule; passive transport remedies this by allowing many important molecules to pass through naturally without extra energy used. This saved energy can be used to perform many other cell functions.

Passive transport also maintains homeostasis for the cell by adhering to the concentration gradient. When particles diffuse from high to low conc., they are helping to maintain balance so that the cell is not overwhelmed by too much or too little of something.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

The Importance of a Selectively Permeable Membrane

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode #57 called The Importance of a Selectively Permeable Membrane. Today we will be discussing The Importance of Selective Permeable Membrane

Segment 1: Introduction to the Selective Permeable Membrane

Let’s start out on what a membrane is. When you look at a cell, or even think about a cell. There is typically a thin barrier surrounding the contents of the cell. Plant, animal, eukaryotic or even prokaryotic, they all have a membrane. This little barrier is made out of a phospholipid bilayer. The lipids bond their tails, which are hydrophobic. Their hydrophilic heads bond together as well creating a wall. Sometimes in the cracks of this wall are proteins. These proteins are either integral, or goes all the way through the wall, or peripheral, which only goes into the wall a little. These proteins are the key to the cell wall being semi permeable. Now what does that word even mean? Semi permeable means the cell membrane only lets in specific molecules, depending on the size and shape of the molecules. The cool thing is that some proteins are also defined as active transport. Which means they need energy to allow molecules to move through the membrane. They act sort of like a clothespin, on the side that's on the outside stays open. When the right molecule enters the open chamber, it closes which in turn opens the other side, and allows the molecules to freely float past. The other type of transport is passive, which is just a protein with a specific size hole, that certain molecules can float freely past. It is key that the cell membrane filters what enters and exits the cell. The diffusion of substances through the cell membrane allows for the cell to be properly maintained and protected.

Segment 2: More About the Selective Permeable Membrane

The cell is a delicate arrangement of organelles that work together in harmony. Each organelle has a defined function that is essential for the survival of that cell, and neighboring cells. If the integrity of this cell is compromised, then surrounding cells along with that one could perish. It may not be that much of a problem because cells on us die every day. However, in either smaller organisms or essential cells, such as the heart or brain, this could be particularly harmful. In order to know why a selectively permeable membrane is so essential to the survival of cells, we have to look closer as to what it does. Let's start with the excrement of substances. Depending on the metabolic activity of the cell, the byproduct of the reaction doesn’t just stay in the cell. It passes through the membrane and exits the cell. It is important that the cell loses the byproduct because it is useless to the cell. An abundance could cause the cell to rupture because of the lack of space. The other role the membrane has is keeping the cell protected from outside threats as well as maintaining homeostasis. The cell membrane serves as a line of defense because it forbids any useless molecules to enter and potentially harm the cell. This filter is essential for the life and efficiency of the cell. Allowing useful molecules for metabolic purposes, DNA replication, vitamins or even just to balance out the cell.

Segment 3: Connection to the Course

This connects with the rest of the unit by explaining specific functions of each organelle while even tying in macromolecules. The use of proteins for diffusion as well as the use of lipids for the protection of the cell, it all ties together. It explains why cells become hypotonic or hypertonic as a result of surrounding solute gradients. It explains how molecules such as glucose or oxygen either get in or out of the cell, helping it metabolize. And finally, it explains how complex cells really are. There are a lot of factors that come into play when dealing with cells. Just looking at the membrane, we can see how outside molecules get in and we see the first line of defense of every cell.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Cell Size (Surface Area to Volume Ratio)

Hopewell Valley Student Publications Network — Fri, 14 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Adrienne Li and I am your host for episode #56 called Unit 2 Cell Structure and Function: Cell‌ ‌Size‌. Today we will be discussing ‌the concept of surface‌ ‌area‌ ‌to‌ ‌volume‌ ‌ratio and how it contributes to cell size and efficiency.

Segment 1: Introduction to Cell‌ ‌Size‌

To start with the basics, cells are incredibly small and on average have a diameter of 100 micrometers. To understand why cells are so small, it’s important to address the concept of surface area to volume ratio. A cell’s surface area is the amount of cell membrane available for diffusion and how much diffusion that can happen at one time. On the other hand, its volume is amount of cytoplasm contained within the cell membrane and how long It takes to get from the membrane to the center of the cell by diffusion. Accordingly, as the ratio between surface area and volume increases, the cell efficiency increases because an increased surface area allows more nutrients and waste to enter and exit the cell. This is why cells are so small because it allows for more reactions to occur. In order to increase surface area, cells take on a complex folding shape and once it reaches a point where the surface area doesn’t allow enough nutrients to pass, the cell divides or dies. However, cells aren’t too small either because then, hereditary material and organelles would not be able to fit and the surface area would not be large enough to adequately exchange materials.

Segment 2: More About Cell‌ ‌Size‌

To illustrate cell size and the importance of surface area to volume ratio in real life, an example is seen in red blood cells which deliver oxygen to body tissues. They have a biconcave disc shape where the diameter at the thickest point is 2–2.5 micrometers and 0.8–1 micrometers at the thinnest point. Because they have that impression in the middle, it increases the surface area of the red blood cell. As a result, it increases the rate that oxygen is exchanged and allows the red blood cell to function efficiently. This is also seen in mitochondria where its inner membranes, called the cristae, have complex folds. This is where the electron transport chain is located which passes electrons from NADH and FADH2 to molecular oxygen and creates an electrochemical gradient that stores energy used to create ATP during chemiosmosis. Since these folds increase the surface area of the mitochondria, it increases the rate of ATP synthesis because there is more space for more embedded proteins to carry out reactions. Another example is seen in gut epithelial cells which play a role in digestion and water and nutrient absorption. These cells have microvilli which are integral to their function because the hair like protrusions increase the surface area so nutrients are absorbed quicker into the blood stream.

Segment 3: Connection to the Course

To dig deeper into cell size and its connection to Cell Structure and Function, we can take a look at the three previous examples. In each example, the cell or organelle’s structure allows it to have the greatest surface area. With an increased surface area, more reactions occur which increases the cell’s efficiency. Accordingly, this is why cells are the size they are and have the structures they have because it allows them to function optimally. If the red blood cell wasn’t shaped like a concave disc, it would have less surface area and diffuse oxygen at a slower rate. If the mitochondria’s inner membranes didn’t have folds, it would also have less surface area and synthesize ATP at a slower rate. And lastly, this is the same for the epithelial cells where if they didn’t have villi, they would have less surface area so the nutrients would be absorbed at a slower rate. So as you can see, cell size plays an integral role in cell structure and function because it determines how well a cell can carry out its functions. And that sums up this episode about cell size.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Function of the Cell Wall

Hopewell Valley Student Publications Network — Thu, 13 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode #55 called Unit 2 Cell Structure and Function: Function of the Cell Wall. Today we will be discussing the cell wall and its importance to living organisms.

Segment 1: Introduction to Function of the cell Wall

The cell wall is a unique structure to plants, fungi, and some prokaryotic organisms. This structure surrounds the cell’s plasma membrane and provides structural support and protection to the organelles and the cell against mechanical and osmotic stress. The cell wall provides strength, shape, and rigidity to the cell, it is responsible for transporting substances between the interior and exterior of the cell, it acts as a barrier, it functions as a storage unit by storing carbohydrates for use in plant growth, and it allows for turgor pressure which is exerted by fluid in the cell that presses the cell membrane against the cell wall.

Segment 2: More About Cell wall

So now that you know what the cell wall does, we can take a closer look at what exactly it is made off. The plant cell wall is mainly made of cellulose which, fun fact, is the most abundant macromolecule on earth. Along with cellulose the cell wall is also composed of microfibrils, hemicellulose, pectin, lignin, and soluble protein. These components are arranged in layers. The first layer is the primary cell wall, and this is positioned closest to the inside of the cell. It mainly consists of pectic polysaccharides and structural proteins, and It is permeable and thinner than the other layers. This layer provides the strength and flexibility needed for cell growth. The next layer is the middle lamella which is the outermost layer. It primarily consists of pectic and it acts as an interface between the other neighboring cells. It also glues them together. The last layer is the secondary cell wall. It is formed inside the primary cell wall and it can consist of cellulose and lignin. It can provide additional rigidity and waterproofing. This layer also gives the cell the square/rectangular shape. It is the thickest layer and is permeable, along with the whole cell wall. In fungi the cell wall is primarily made of chitin. Fungi also have hydrophobins which gives the cell strength, helps it adhere to surfaces, and helps control the movement of water into the cell. In prokaryotes the cell wall is primarily composed of peptidoglycans. It contains an inner peptidoglycan layer and an outer layer composed of lipoproteins and lipopolysaccharides. A unique property of the cell wall is that it is fully permeable to smaller molecules while the membrane is selectively permeable.

Segment 3: Connection to the Course

The cell wall is a vital component to plants, fungi, and some prokaryotic organisms. It provides unique properties that allow for these organisms to survive. For example, turgor pressure, as a I mentioned earlier, is the pressure of the cell contents against the cell wall. This is what allows for organisms to hold water and maintain a solid structure. Turgor pressure decreasing means that the plant has lost water. Visually, the loss of turgor pressure can be seen by a wilted flower or leaf. If a plant cell did not have a cell wall, turgor pressure would not be able to happen because the cell membrane cannot support a hypotonic environment, therefore the cell would burst. Another important property of the cell wall is that it provides strength and structure to the cell. This is very important because it helps protect the cell from damage that would be more susceptible too if there was no cell wall. Cell walls also store carbohydrates that plants use for growth. Finally, the last unique property of cell walls I'm going to talk about is plasmodesmata, which are pores or channels between plant cell walls that allow molecules and communication signals to pass between individual plant cells. Without a cell wall, a lot of organisms would not be able to survive, this is why they are so vital.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Movement Organelles (Cilia and Flagella)

Hopewell Valley Student Publications Network — Wed, 12 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode 54 called Unit 2 Cell Structure and Function: Movement Organelles. Today we will be discussing cilia and flagella, which are known as the movement organelles of the cell due to their importance in the movement and locomotion of cells through different means. I’ll be starting off by giving an introduction to Cilia and Flagella (so, talking about their structure and what they both are exactly). Afterwards, I’ll go through the variety of functions that cilia and flagella partake in and take on. Finally, I will place cilia and flagella into the broader scope of “cell structure and function” and expand a little bit on their importance and finish off by quickly presenting the consequences if cilia and flagella were absent.

Segment 1: Introduction to Cilia and Flagella

Cilia and flagella overview
Tube like appendages that allow for motion in eukaryotic cells
Cilia - found in both animals and microorganisms, but not in most plants
Flagella - mostly used for motility in bacteria and gametes of eukaryotes
Cilia structure
Small hair-like protuberances on the outside of eukaryotic cells
Responsible for locomotion of cell itself or of fluids on cell surface
Involved in mechanoreception - detection/response of animals to stimuli
Structure
Made up of microtubules coated in plasma membrane
Microtubules - small hollow rods made of protein tubulin
Contains 9 pairs of microtubules forming the outside of a ring; two central microtubules (axoneme) - microtubules held together by cross-linking proteins
Dyneins - motor proteins between the 9 outer pairs - allow cilia to be motile
Proteins (hydrolyze ATP for energy) undergo conformational changes which allow for complex movements - cause the bending in the cilium as microtubules slide
Cilia - 0.25 micrometers in diameter and 20 micrometers in length
Found on cell surface and beat back and forth to create movement
Non-motile cilia
Don’t have the center microtubule structure or dynein arms - can’t move
Flagella structure
Hair life organelles - longer and less numerous protrusions
Used by cells and microorganisms for movement
Specialized flagella in some organisms used as sensory organelles that can detect changes in temperature and pH
Eukaryotic
Very similar to cilia
Have 1+ (generally many) flagella which move in a whiplike way
Core is a bundle of 9 pairs of microtubules surrounding 2 central microtubules like cilia, sliding of microtubules cause movement, etc.
Depend on ATP for energy
Prokaryotic/Bacterial
Helically shaped structures that contain the protein flagellin
Base of flagellum near the cell surface is attached to the basal body and the flagellum rotates in a clockwise or counterclockwise direction
Get energy from this proton motive force across the cell membrane

Segment 2: More About Cilia and Flagella

Cilia Function
Important in movement of cell itself or of substances that go past the cell
In ciliates, cilia responsible for the movement of the whole organism such as the unicellular protist Paramecium (cilia responsible for the movement and feeding)
Help to remove contaminants from organs or tissues by helping to move fluids over the cell
Lining of the nasopharynx and trachea covered in cilia - ciliated epithelial cells remove mucus, bacteria, and other debris from the lungs
Present in the lining of the fallopian tubes - help in fertilization by movement of the egg towards the uterus
Non-motile cilia
Sensory apparatus for cell - detect signals
Play roles in sensory neuron
Found in the kidneys to sense urine flow
In eyes on the photoreceptors of retina where they function to transport vital proteins from the inner segment of the photoreceptor to outer segment through sense and initiating movement
Provide habitats for symbiotic microbiomes in animals
Known to filter, clear, localize, select, and aggregate bacteria and control adhesion for ciliated surfaces
Flagella Function
Used to propel a cell (ex: bacteria and sperm) through liquid
Specialized functions
Some eukaryotic cells used flagellum to increase reproduction rates
Eukaryotic and bacterial flagella are used to sense changes in the environment, such as temperature or pH disturbances
Found in sponges and other aquatic species to help move water for respiration
Eukaryotic flagella can serve as sensory organelles
Flagella may be used as a secretory organelle

Segment 3: Connection to the Course: Cell Structure and Function

Prokaryotic and eukaryotic cells contain cilia and flagella - aid in cell movement and movement of substances around cells and along tract
Consequences of lack of cilia/flagella
Cells unable to move to attain food and nutrients
Cell cycle affected - proteins would not be able to function properly
Reproduction would likely not occur
Cell communication would be affected
Contaminants may not move past cell and could negatively harm the cell
Cell can’t swim away from non ideal conditions or invaders
Transport of certain proteins and bacteria would not occur
Cells may not be able to detect signals - reaction to stimuli would be affected

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Lysosomes and Vacuoles

Hopewell Valley Student Publications Network — Wed, 12 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode #53 called Unit 2 Cell Structure and Function: Lysosomes and Vacuoles. Today we will be discussing the importance of each in regards to the cells and our bodies, and how they fit into the overarching topic of Cell Structure and Function.

Segment 1: Introduction to Lysosomes and Vacuoles

We will begin by discussing what exactly lysosomes and vacuoles are and why they are so important for our cells to contain
Both of these are essential organelles, and organelles are subcellular structures with specific jobs to perform in the cell, much like an organ does in the body
Lysosomes are membrane-bound sacs of enzymes which digest cellular macromolecules
They are made by proteins from the ER and enclosed in vesicles by the Golgi apparatus and are formed by budding from the Golgi apparatus
They break down excess cell parts, and can be used to destroy invading viruses and bacteria so if the cell is damaged beyond repair, lysosomes can help it self-destruct through a process called apoptosis
Lysosomes also play a role in phagocytosis which is when a cell engulfs a molecule to break it down which is known as “cell eating”
White blood cells have more lysosomes than other cells because they destroy bacteria, dead cells, cancerous cells, and foreign matter through disgestion
Vacuoles are fluid-filled enclosed structures separated from the cytoplasm by a single membrane which are found mostly in plant cells and fungi
They have a less prominent role in some protists, animal cells, and bacteria and in animal cells they function to sequester waste products; in plant cells, they help maintain water balance
Overall, they function to provide nutrient storage, detoxification, and as waste exportation
Vacuoles are also known as “specialized lysosomes” because both function to get rid of waste products, but when that product is water, the vacuole activates its function to balance water inside and outside a cell

Segment 2: More About Structure/Function of Lysosomes and Vacuoles

Above is a picture of the structure of lysosomes which are generally known to be very acidic meaning it has to be protected from the rest of the inside of the cell
The membrane around it stores the digestive enzymes that require the acidic, low-pH environment, also known as hydrolytic enzymes
Hydrolytic enzymes break down large molecules into smaller ones such as large amino acids into smaller proteins and by doing so they provide necessary nutrients to the rest of the cell
Storing the large molecules is detrimental to your health and can cause disease
Another type of lysosome storage disease is where the small molecules that are produced from those large molecules can't get out of the lysosome
They're stored there because the transporters for moving these small molecules out are missing genetically
Above, is a picture of the vacuole which is similar to vesicles, another organelle, because both are membrane-bound sacs, but vacuoles are significantly larger than vesicles and are formed when multiple vesicles fuse together
Filled tight with water, the vacuole pushes the cytoplasm into a thin strip adjacent to the membrane and pushes outwards like a water filled balloon; it is this turgor pressure that holds the cell firm and provides the characteristic shape of plant structures such as leaves.
So when the plant has been without water for a long time, the central vacuoles lose water, the cells lose shape, and the whole leaf wilts

Segment 3: Connection to the Course

Lysosomes and vacuoles fit into the bigger picture of cell structure and function because they contribute to supporting the origin of eukaryotic cells, one of the big ideas of Unit 2
Eukaryotic cells arose through endosymbiotic events that which rise to the energy-producing organelles within the eukaryotic cells such as the lysosomes and vacuoles
Living systems are organized in different structural levels that interact with each other to contribute to the survival of organisms
They also affect living systems through their presence in cells because of their specific structures and functions
Their specific structural elements allow for the cell to help organisms capture, store, and use energy

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Macromolecules that Make up the Cell Membrane

Hopewell Valley Student Publications Network — Tue, 04 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Nikki Evich and I am your host for episode #52 called Unit 2 Cell Structure and Function: Macromolecules that make up the Cell Membrane. Today we will be discussing the structure of the cell membrane.

Segment 1: Introduction to the fluid mosaic model

So what is a fluid mosaic model?

A fluid mosaic model describes the structure of the plasma membrane as a mosaic of components that gives the membrane a fluid character
fluid combination of phospholipids, cholesterol, and proteins.
All in all- made up of a bunch of different molecules that are distributed across the membrane. If you were to zoom in on the cell membrane, you would see a pattern of different types of molecules put together, also known as a mosaic. These molecules are constantly moving in two dimensions, in a fluid fashion, similar to icebergs floating in the ocean.

Segment 2: More About each macromolecule

Lipids

Phospholipid bilayer- made of of hydrophobic tails and hydrophilic heads
Saturated fatty acids are chains of carbon atoms that have only single bonds between them. As a result, the chains are straight and easy to pack tightly. Unsaturated fats are chains of carbon atoms that have double bonds between some of the carbons. The double bonds create kinks in the chains, making it harder for the chains to pack tightly
Double or triple bonds- not organized
Saturated better organized
Cholesterol-help with structure and fluidity of the because they prevent the phospholipid bilayer from separating too far
The cholesterol molecules are randomly distributed across the phospholipid bilayer, helping the bilayer stay fluid in different environmental conditions.
Without cholesterol, the phospholipids in your cells will start to get closer together when exposed to cold, making it more difficult for small molecules, like gases to squeeze in between the phospholipids like they normally do. Without cholesterol, the phospholipids start to separate from each other, leaving large gaps.
Carbons
Glycolipid- lipid with a carb attached outside of cell membranes
Help stabilize membrane structure
Glycoprotein-protein with a carb attached
Help stabilize membrane structure
Proteins
Many different proteins
Channel proteins
acts like a pore in the membrane that lets water molecules or small ions through quickly ○ Peripheral proteins (hang on side)
transport or communication
Integral protein (all the way through)
transporting larger molecules, like glucose, across the cell membrane. They have regions, called “polar” and “nonpolar” regions, that correspond with the polarity of the phospholipid bilayer
What affects cell fluidity besides
Temperature-high lipids spread, low they get too close

Segment 3: Connection to the Course

Why is the cell membrane so important?

Fluid form makes it not totally closed off but
permeable-permeability is very important so the cell can import and export
needed materials
Plays a role in homeostasis
Allows cell to survive in diverse environments
We learned about all the different macromolecules and how
they make up cells- this is an example of how macromolecules make up an
integral part of the cell

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Comparing the Energy Related Organelles

Hopewell Valley Student Publications Network — Tue, 04 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode #51 called Unit 2 Cell Structure and Function: Comparing the Energy Related Organelles. Today we will be discussing the similarities and differences between the mitochondria and chloroplast.

Segment 1: Introduction to the energy related organelles

Both eukaryotes and prokaryote cells need energy to function. Eukaryotes rely on the mitochondria and chloroplast to provide their cell with energy. The Mitochondria and the chloroplast also both contain their own DNA and are able to grow and reproduce independently within the cell. Mitochondria are found in plant and animal cells while chloroplasts are found only in plant cells. The mitochondria work to convert oxygen and nutrients into ATP through a process known as cellular respiration. Without a mitochondrion, many animals would not exist because they would not be able to obtain enough energy. The mitochondria enable cells to produce 15 times more ATP than they could otherwise. The number of mitochondria in a cell depends on the metabolic requirements of that cell. They were first discovered in the 1800s but until the 1950s they were believed to transmit hereditary information. In contrast, the chloroplast produces energy through photosynthesis. It has a high concentration of chlorophyll, the molecule that captures light energy, and this gives many plants green color. Chloroplasts are essential for the growth and survival of plants and photosynthetic algae. Chloroplasts take light energy and convert it into energy stored in the form of sugar and other organic materials. Cells need both chloroplasts and mitochondria to undergo both photosynthesis and cell respiration. After photosynthesis, which occurs through the chloroplast, that produces oxygen and glucose, plants need to break down the glucose and they use cellular respiration to do this, which happens in the mitochondria. There Is one plant that does not have a chloroplast, Rafflesia, which obtains its nutrients from other plants. Since it gets all of its energy from parasitizing another plant, it no longer needs its chloroplasts, and has lost the genes coding for the development of the it.

Segment 2: More About the the Mitochondria and Chloroplasts

There are many similarities and differences between the structures of the 2 organelles. Mitochondria have an inner and outer membrane, with an intermembrane space between them. The outer membrane contains proteins known as porins, which allow the movement of ions into and out of the mitochondrion. The space within the inner membrane of the mitochondria is known as the matrix, which contains the enzymes of the Krebs and fatty acid cycles, alongside DNA, RNA, ribosomes and calcium granules. The inner membrane contains a variety of enzymes. It contains ATP synthase which generates ATP in the matrix, and transport proteins that regulate the movement of molecules into and out of the matrix. The inner membrane is arranged into folds known as cristae in order to increase the surface area available for energy production. Chloroplasts are surrounded by a double membrane similar to the double membrane found within a mitochondrion. Within the chloroplast is a third membrane that forms stacked, disc-shaped structures called thylakoids. Embedded in the thylakoid membrane are molecules of chlorophyll. A stack of thylakoids is called a granum, and the space surrounding the granum is called the stroma. Just like the structure of the mitochondria was important to its ability to perform aerobic cellular respiration, the structure of the chloroplast allows the process of photosynthesis to take place.

Segment 3: Connection to the Course

The mitochondria and chloroplast can be connected to the greater theme of cell organelle functions and the endosymbiotic theory. The similar function of the mitochondria and chloroplast allows us to understand how a cell gets energy and functions as well as how the function of these 2 organelles impacts the other organelles in a cell. The endosymbiotic theory is based on the fact that both the mitochondria and chloroplast can produce their own energy being able to reproduce independently and contain their own DNA. This provides possible evidence that mitochondria and chloroplasts may have existed as prokaryotes before joining with other organelles to form eukaryotic cells.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

The Making of a Protein (Organelles and Path)

Hopewell Valley Student Publications Network — Tue, 04 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Alex and I am your host for episode 50 called Unit 2 Cell Structure and Function: The Making of a Protein. Today we will be discussing the process of how proteins are formed inside cells.

Proteins are one of the most important macromolecules. They are responsible for many essential functions in the body. They come in many forms such as enzymes, antibodies, and hormones.

But how are proteins created in the body?

First, transcription occurs to produce mRNA. DNA in the nucleus unwinds to expose the bases to act as a template. DNA polymerase breaks the hydrogen bonds between the bases. RNA polymerase then takes the exposed bases to create an RNA chain from the DNA. Once the whole strand is copied, the mRNA leaves the nucleus through the nuclear envelope pores. The mRNA then goes under some modifications such as adding a protective cap to protect the mRNA from enzymes. Furthermore, introns, or Junk DNA, is removed from the mRNA.

Afterwards, the mRNA attaches to a ribosome in the cytoplasm, and begins the process of translation. Here the ribosome will work down the mRNA strand, 3 nucleotides at a time. The ribosome will take the 3 nucleotides and assign the corresponding amino acids to be linked.

Now, the polypeptide chain undergoes three stages of folding to shape the protein for its specific function. The protein first folds using hydrogen bonds to hold the new structure together into a secondary structure such as an alpha helix. The next two steps are very similar to the first, with the protein undergoing further stages of folding to create a complex quaternary structure.

Protein synthesis is one of the most vital aspects of biology. Organisms had evolved to use DNA as a blueprint for synthesizing proteins, which allows a cell to create a menagerie of different proteins to carry out different tasks.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

· Twitter @thehvspn

Comparing and Contrasting the Prokaryotic and Eukaryotic Cells

Hopewell Valley Student Publications Network — Tue, 04 May 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode #49 called Unit 2 Cell Structure and Function: Comparing and Contrasting the Prokaryotic and Eukaryotic Cells. Today we will be discussing the comparison between the functions and structures of these two cell types.

Segment 1: Introduction to Prokaryotes and Eukaryotes

The main difference between prokaryotic and eukaryotic cells is the presence of the nucleus and other internal membranes. This lack of membrane in prokaryotic cells often causes them to lack crucial organelles which are present in Eukaryotic cells.
In Eukaryotic cells, the genetic information, the DNA, is held within the nucleus.
In a prokaryotic cell, the genetic material is carried on a singular piece of DNA which is attached to the cell membrane, and there is no enclosing membrane which causes the genetic information to come into direct contact with the cytoplasm. (This whole system is called a nucleoid, a concentration of DNA)
Overall, the main difference is the presence of membrane bound organelles in eukaryotic cells, and absolutely no membrane bound organelles or a nucleus at all in prokaryotic cells.

Segment 2: More About Prokaryotes and Eukaryotes

Going more in depth, prokaryotes are ultimately unicellular organisms. In contrast, eukaryotic organisms can be unicellular, but eukaryotes are the building blocks of larger organisms

Two examples of prokaryotes include bacteria and archaea. Eukaryotic cells make up everything besides these two organisms including fungi, plants, and animals.
Specific similarities between the organelles present in both prokaryotic and eukaryotic cells is that they both contain a plasma membrane, ribosomes, cytoplasm, and DNA. Although they carry genetic information differently, it is important to remember that they both still possess it.
It's important to understand the origin of these two different cells, and how it came about that they have different contents. According to the endosymbiotic theory, it is believed that two or more prokaryotic cells, living in a symbiotic relationship with each other, ultimately evolved into the mitochondria, present in only eukaryotic cells. One prokaryotic may have engulfed another, created an enclosed membrane for the new organelles that were being created by the presence of two prokaryotic cells.

Segment 3: Connection to the Course

The endosymbiotic theory is very critical to the evolution aspect of all living things. Because two prokaryotic cells were able to work together in their own beneficial way to make a eukaryotic cell, which now make up all living things besides bacteria and archaea, is very significant. Once the eukaryotic cells were created, evolution was able to take its course, and lead us to where we are now. The creation of the membrane bound nucleus in eukaryotic cells made a huge structural difference, and made complex evolution possible. Overall, both prokaryotic and eukaryotic cells play a major role in the biological world, but it is especially important to appreciate how the eukaryotic cells were created, and how evolution took place after this occurrence.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Nucleic Acids Structure and Function

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #48

Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode #48 called Unit #1 Chemistry of Life: Nucleic Acids Structure Function & Examples. Today we will be discussing an overview of nucleic acids in terms of their components, function, and examples.

Segment 1: Introduction to Nucleic Acids Structure Function & Examples

Nucleic Acids are one of the big macromolecules necessary for life. They are complex organic substances present in living cells whose molecules consist of many nucleotides linked in a long chain. Let’s first talk about what makes up nucleic acids. Their monomers are nucleotides which are all made up of a phosphate group, a pentose sugar, and a nitrogenous base as shown in the diagram. The nitrogen atoms in the nitrogenous base are the extra element that differentiates nucleic acids from the three other macromolecules with the abbreviation CHOPN. Through a dehydration reaction, nucleotides link together with a phosphodiester linkage which is between the sugar and phosphate groups. The drawing shows a water molecule taken out to form this a covalent bond. The nucleotides bonded together make up the polymers of nucleic acids which are DNA and RNA.

Segment 2: Example of Nucleic Acids Structure Function

DNA and RNA are the main two examples of nucleic acids. There are major differences as well as similarities between DNA and RNA that are important to know. DNA, also known as deoxyribonucleic acid, is made up of the deoxyribose sugar, is double stranded and arranged in an antiparallel pattern. DNA is always found in the nucleus of eukaryotic cells and contains information for thousands of proteins. Its bases are cytosine, guanine, adenine, and thymine. On the other hand, RNA uses all of these bases except thymine is replaced by uracil. RNA is also only single stranded and contains information for only one protein as it leaves the nucleus after formation. They are similar in their directionality and bonding. Their nucleotides are all linked by covalent bonds and have a 3’ to 5’ directionality. The linear sequence of nucleotides have ends, defined by the 3’ hydroxyl and 5’ phosphates of the sugar in the nucleotide. During DNA and RNA synthesis, nucleotides are added to the 3’ end of the growing strand, resulting in the formation of a covalent bond between nucleotides.

Since DNA is structured as an antiparallel double helix, each strand runs in the opposite 5’ to 3’ orientation. This means that adenine nucleotides pair with thymine nucleotides via two hydrogen bonds. Cytosine nucleotides pair with guanine nucleotides by three hydrogen bonds. This is all shown in this diagram where the black boxes are where another nucleotide would be added, and there are more hydrogen bonds highlighted in pink between Guanine and cytosine because of the antiparallel double helix.

Segment 3: Digging Deeper Nucleic Acids Structure Function & Examples

Nucleic acids fit in the greater picture of the unit called Chemistry of Life because of their functions. As mentioned before, they carry information for making proteins which brings back the topic of the central dogma. Through transcription, the information in a strand of DNA is copied into a new molecule of messenger RNA, which is then decoded during the process of translation to build a polypeptide. Humans cannot survive without all nine essential amino acids found in proteins, so nucleic acids are essential for protein synthesis. DNA and RNA also have a hereditary function because it is inherited from parent to offspring, so is responsible for any gene mutations and the genetic biodiversity of populations. Just to highlight just how important nucleic acids are, DNA is the blueprint for life.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Carbohydrates, Lipids, Proteins, and Diet

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 2 Cell Structure and Function

Segment 1: Introduction to Passive Transport.

For cells to survive, they must take in or expel certain particles and substances. What monitors their entry or exit is the plasma membrane in a process known as membrane transport.
Two types of transport: active and passive.
Active requires ATP energy, cell is purposely doing it
But today focusing on passive transport, where no energy is required to move materials in or out, natural process known as diffusion
3 main types: Simple diffusion, osmosis, and facilitated diffusion
In all types, movement is based on a concentration gradient, substances move from areas of high conc. To low, whether this is in or out of cell
Seeking equilibrium, a balance in concentration

Segment 2: More About Passive Transport

Start with simple diffusion
The movement of particles down the concentration gradient across the semipermeable lipid membrane.
If there is a greater concentration of a particle on one side of the membrane, simple diffusion will occur and the particle will move to the area of lower concentration.
These particles must be small and non-polar, as only these types of particles can make their way through the lipid membrane.
For example CO2 and O2, CO2 is often produced and of high conc. Within cells so it will diffuse outwards. O2 is often present in higher conc. Out of cell, so it will typically diffuse inwards.
A useful analogy would be to think about the smell of cooking wafting through the house. When you cook, the food molecules are highly concentrated in the air around the stove, so the smell is strongest around there. However, the food molecules will soon diffuse throughout the house into areas of lower concentration, which is why the smell of the food will eventually reach you in a different room.
Osmosis: A type of simple diffusion except with water as the specific particle diffusing
Specifically, movement of water molecules down the concentration gradient across semipermeable lipid membrane
Water in an area with higher conc. Of water vs solute Will diffuse into an area with lower concentration of water. Vs solute
If placed in a hypertonic solution, where the concentration of solutes is higher than the cell, water will flow out of the cell and into the solution to balance out the lower conc. Of water outside
If placed in a hypotonic solution, where conc. Of solutes are lower than the cell, water will flow into the cell to balance out the lower conc. Of water in it
Osmosis’s ultimate goal however is to create an isotonic environment, where the concentration of solute and water is equal inside and outside of the cell. In this case, water will still be flowing in and out, and cells will be able to function normally.
Facilitated diffusion
Sometimes simple diffusion will not work, as certain particles are blocked by the semi-permeable cell membrane whether due to size or polarity
Cell still needs these particles, so they must find another way to get them: this way is facilitated diffusion
Facilitated diffusion occurs with the help of specialized proteins called channel proteins and carrier proteins. These proteins provide a larger opening for needed molecules to pass through passively.
Channel proteins are not specialized for certain molecules, and will like the cell membrane discriminate based on size (only for channel proteins, size allowance is larger)
Often carry across ions
An example of channel protein is an aquaporin, designed for quick transport of water, quicker than the time needed to cross cell membrane
Carrier proteins are often more specialized, usually taking in only one specific type of molecule, and undergo a specific process when transporting the molecule]
The carrier channel will mold itself to the shape of the particle before guiding it into or out of the cell
This is why it is so selective, as different molecules have distinct shapes that specialized carrier proteins may not accept
An example of a molecule transported by carrier proteins is glucose. Glucose is a large polar molecule that cannot undergo simple diffusion, so it must be specifically move into the cell by a carrier protein

Segment 3: Connection to the Course

Passive transport and its 3 types are important for many reasons
Most significantly, bring in particles/molecules vital to the survival of the cell, such as water and sugars
Works in tandem with active transport. Cell cannot wastefully expend ATP on bringing in every type of molecule; passive transport remedies this by allowing many important molecules to pass through naturally without extra energy used. This saved energy can be used to perform many other cell functions.
Passive transport also maintains homeostasis for the cell by adhering to the concentration gradient. When particles diffuse from high to low conc., they are helping to maintain balance so that the cell is not overwhelmed by too much or too little of something

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Impact of Temperature and pH on Enzymes

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #46

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode 46 called Unit 1 The Impact of Temperature and pH on enzymes. Today we will be discussing what an enzyme is and how the pH and temperature of the environment affects the enzyme and its substrate.

Segment 1: Introduction to The Impact of Temperature and pH on enzymes

An enzyme is a protein or a RNA molecule that acts as a catalyst in chemical reactions, helping to reduce the activation energy needed for the reaction to occur. Often, this speeds up the rate of reaction. Enzymes are not changed or consumed by the reactions they catalyse and as a result can be reused. Enzymes are typically named after the molecules they react with, which is called the substrate, and they end with the suffix ‘-ase’. The active site is the region on the surface of the enzyme which binds to the substrate molecule. The active site and the substrate complement each other in terms of both shape and chemical properties. Enzymes are selective and each enzyme only speeds up a specific reaction. pH is a scale from 1-14 used to specify how acidic or how basic a solution is. A number lower than the neutral 7 is considered an acid while a number higher than 7 is a base. With enzymes, changes in pH can affect active sites by changing its shape or charge and making it harder for substrates to bind. Small changes in pH above or below the Optimum for the enzyme do not cause a permanent change to the enzyme, since the bonds can be reformed. However, extreme changes in pH can cause enzymes to Denature and permanently lose their function. The optimum pH, or the pH where the enzyme is most active, depends on where it normally works. For example, enzymes in the small intestine have an optimum pH of about 7.5, but stomach enzymes have an optimum pH of about 2. Low temperatures result in insufficient thermal energy for the activation of a reaction to proceed. Increasing the temperature will increase the speed and motion of both enzyme and substrate, resulting in higher enzyme activity since a higher kinetic energy will result in more frequent collisions between the enzymes and substrates. At an optimal temperature for the enzyme, the rate of activity will be at its peak. Higher temperatures will cause enzyme stability to decrease, because the thermal energy disrupts the enzyme’s hydrogen bonds. This causes the enzyme’s active site to lose its shape, resulting in denaturation.

Segment 2: Example of The Impact of Temperature and pH on enzymes

Trypsin and pepsin are both enzymes in the digestive system which break protein chains in food into smaller peptide chains or into individual amino acids. Pepsin works in the highly acidic conditions of the stomach. It has an optimum pH of about 1.5. On the other hand, trypsin works in the small intestine, parts of which have a pH of around 7.5. If at a pH of around 7, a substrate attaches itself to the enzyme via two ionic bonds, then a change in pH can definitely make it difficult for the substrate to bond to the enzyme. In an example enzyme, the groups allowing ionic bonding are caused by the transfer of a hydrogen ion from a COOH group in the side chain of one amino acid to an -NH2 group in the side chain of another. At a lower pH, the -COO- will pick up a hydrogen ion and with this an ionic bond can no longer form between the substrate and the enzyme. If those bonds were necessary to attach the substrate and activate it, then at this lower pH, the enzyme won't work. With a pH higher than 7, the NH3+ will lose a hydrogen ion and again an ionic bond can’t form. The tertiary structure of the protein is also in part held together by ionic bonds. At very high or very low pH's, these bonds within the enzyme can be disrupted, and it can lose its shape and if it loses its shape, the active site can be lost completely. In the human body the optimum temperature for an enzyme is around 37 degrees celsius. However, some enzymes work better at lower temperatures and some work well at higher temperatures. For instance, animals from the Arctic have enzymes adapted to have lower optimum temperatures while animals in desert climates have enzymes adapted to higher temperatures. While higher temperatures do increase the activity of enzymes and the rate of reactions, temperatures above 40 degrees Celsius, will start to break them down.

Segment 3: Digging Deeper into The Impact of Temperature and pH on enzymes

The impact of temperature and pH on enzymes can be connected to the greater picture of macromolecules. Proteins are made of units called amino acids, and in enzymes that are proteins, the active site gets its properties from the amino acids it's built out of. These amino acids may have side chains that are large or small, acidic or basic, hydrophilic or hydrophobic. The set of amino acids found in the active site, along with their positions in 3D space, give the active site a very specific size, shape, and chemical behavior. Due to these amino acids, an enzyme's active site is uniquely suited to bind to a particular target, the enzyme's substrate, and help them undergo a chemical reaction. Dehydration and hydrolysis reactions are catalyzed by specific enzymes and a specific enzyme breaks down each macromolecule. For instance, amylase, sucrase, lactase, or maltase break down carbohydrates. Enzymes called proteases, such as pepsin and peptidase, and hydrochloric acid break down proteins. Lipases break down lipids. These broken down macromolecules provide energy for cellular activities.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Enzyme Substrate Complex

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #45

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode #45 called Unit 1 Chemistry of life: Enzyme substrate complex. Today we will be discussing how enzymes interact with their specific substrates.

Segment 1: Introduction to Enzyme Substrate Complex

It’s important to understand what enzymes are first before looking into their relationship with substrates. Enzymes are proteins that increase the activation energy of a chemical reaction. Each enzyme is specific to a certain substrate. A substrate is the substance on which the enzyme acts. Enzymes are usually named after their substrate with the ending -ase. For example, lactase is the enzyme that breaks down lactose. Enzymes and substrates work in a key and lock relationship. The Enzyme substrate complex is when the substrate binds to the enzyme’s active site and creates a molecule. The enzyme works to break apart the substrate into products, ultimately increasing the activation energy

Segment 2: Example of Enzyme Substrate Complex

As stated before, enzymes and substrates are specific to one another, and they cannot work together unless the enzyme is the right shape. Although this may not seem important, there are many factors that can affect the way enzymes work. For example, pH levels, temperature, and substrate concentration. Enzymes have an optimal level of activity where they are most productive. In terms of pH, each enzyme has an optimal pH, and extremely increasing this level can cause the enzyme to denature. When an enzyme denatures, this means that the enzyme unfolds and cannot properly bind to the substrate, therefore causing a decrease in activity. In terms of temperature, enzymes have a generally large range of optimal activity, but once the temperature passes the highest optimal temperature, the enzyme will denature at a fast rate. When substrate concentration increases, enzyme activity will also increase until they are working at their fastest rate in regards to how many enzymes are present to work.

Segment 3: Digging Deeper Enzyme Substrate Complex

When amino acids are building proteins, the way that they fold together determines their function. Because enzymes are proteins, their specific fold is very important in regards to how they bind with the substrate. When enzymes denature, this is detrimental to the function of the protein, and the enzyme is unable to work properly.
Enzymes are extremely important to the human body because they speed up the rate of a variety of reactions that help us build muscles, destroy toxins, and break down food particles during digestion.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Proteins Structure and Function

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #44

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode 44 called Unit 1 Ecology: Proteins structure and function. Today we will be discussing everything about proteins.

Segment 1: Introduction to Proteins

You may be asking, what is a protein? Well, a protein is a macromolecule that helps us with muscle growth and development. It is most commonly found in animals and we even produce our own proteins. Such macromolecules are created in the cells of an organism. When it comes to what they look like, the simple answer is, it depends. In simple biology, they mainly talk about them in their primary structure. Which is it’s simplest and most basic structure. It consists of amino acids in a singular line. These amino acids are made up of a centralized alpha carbon, with a amino group, carboxyl group, a singular hydrogen and a variant group stemming from it. Digging deeper into each group, we see that an amino group consists of one Nitrogen with three hydrogens. The carboxyl group has a carbon that is bonded to an oxygen and double bonded with another oxygen. The variant group is anything that defines that amino acid. Any variant of atoms can go here and that is what makes each amino acid unique and different. Now in addition to their primary structure, there is the secondary structure (which is a single helix) tertiary structure and the quaternary structure. All of them are just multiples of the previous structure and each structure plays a different role. Just like how, a quaternary structure is made up of multiple polypeptide chains that connect and form one macromolecule. Now they bond to each other in a specific way. Looking at the primary structure, each group is connected using a peptide bond. This is a covalent bond as a result of losing water. So that means it is a dehydration synthesis reaction. These bonds link the carboxyl group from one amino acid to the amino group of another. The result of this bond is the compound being polar and having a nitrogen and carbon backbone. These bonds could range from one to 1000 different amino acids. The huge giveaway to identifying a protein is the carboxyl group, so look for a carbon double bonded with an oxygen and single bonded with another. And second, identify the amino group, along with the alpha carbon, these are keys to look for when identifying a protein.

Segment 2: Example of Proteins

Proteins and amino acids are found in everything living. They range from different functions such as transportation, structural, defense, storage, enzymes and hormones. For example, in animals, we have living tissue that connects all of our bonds, this is called collagen. It is very strong and is composed of 3 polypeptide chains that are intertwined to form the strong protein that keeps us together. More examples include hemoglobin, keratin, pepsin, insulin and albumin. As you can see, these proteins are what keep us together, they are what we are made of. However, in us, there are extremely useful proteins called enzymes. Enzymes break down compounds into simpler molecules so our body can process them. Enzymes reduce the amount of energy needed for these compounds to break down. They fit into them like a lock and key, while connected, the enzyme dissolves the compound. The body uses the remains for easy energy.

Segment 3: Digging Deeper into Proteins

Looking at this, we see that proteins are quintessential for life. Animal or not, every living organism has it, and every living organism uses it. Protein is a macromolecule of life and nothing can live without it. It is made by the body straight from RNA. It’s structure is unique and it’s open ended side chain leaves room for so many different abilities. One such example is enzymes. The molecules in the side chain have a certain polarity, it repels and attracts itself in such a way that it forms a hole. A hole that is perfect size and shape to fit a specific chemical to break down. The structure and shape of each protein leaves for some variation in function, but no matter the function, nothing can survive without it.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Lipids Structure and Function

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #43

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode #43 called Unit 1 Lipids Structure, Function & Example. Today we will be discussing what lipids are and look at some examples. Then we will take a look at their significance.

Segment 1: Introduction to Lipids, Structure & Examples

First of all, what are Lipids? Well, Lipids are molecules that contain hydrocarbons and yield high energy. They are formed by the chemical linking of small constituent molecules. They consist of a glycerol molecule (which is a small organic molecule with three hydroxyl groups) that is bonded to long hydrocarbon chains and depending on the lipid, they can be bonded to other molecules as well. Lipids are hydrophobic meaning they are nonpolar and insoluble in water. Some are amphipathic. This means that part of the lipid is hydrophobic and another part in hydrophilic. These lipids form molecular aggregates with their hydrophilic ends touching the water and the hydrophobic parts on the inside. This is what oil looks like when mixed with water. So now that we understand what Lipids are, let's take a look at some examples.

Segment 2: Example of Lipids

There are many varieties of lipids, and each of these varieties have different structures and functions. The main groups of lipids are Triglycerides, Phospholipids, Steroids, and Waxes. Triglycerides are your fats and oils. They consist of a glycerol backbone and three fatty acid tails. A fatty acid is a long hydrocarbon chain attached to a carboxyl group. The fatty acid tail is bound to the glycerol backbone via ester linkages, which are linkages containing an oxygen atom next to a carbonyl. Triglycerides can be unsaturated or saturated. In order to be saturated the bonds between neighboring carbons in the hydrocarbon chain have to be single bonds. In order to be unsaturated there has to be at least one double bond between neighboring carbons in the hydrocarbon chain. Saturated triglycerides are called fats and they are solid at room temperature because of their tightly packed. They are mainly found in animals. Unsaturated triglycerides are called oils and they are liquid at room temperature because of their cis structure that causes them to bend so they cant be tightly backed like saturated fats. They are mainly found in fish and plants. Phospholipids consist of a glycerol backbone, two fatty acid tails, and the modified phosphate group occupies the third carbon in the glycerol backbone. These are amphipathic molecules. The fatty acid tail chains are hydrophobic, and the phosphate group head is hydrophilic. Phospholipids are found in biological membranes because of their amphipathic property. Their hydrophobic tails stand as a barrier between the inside of the cell and its surroundings while the hydrophilic ends touch the outside and inside of the cell and allow for only certain components to travel between the membrane. This structure is called a bilayer, and it creates a low-energy, stable arrangement. Steroids are another lipid molecule. Their structure consists of four fused carbon rings. The hydrocarbon tail is connected to the steroid at one end, and the hydroxyl group is connected to the other end. Many steroids have an -OH functional group (called sterols), and some have short tails. Cholesterol is the most common steroid, is mainly created in the liver, and is the precursor to many steroid hormones. For example, sex hormones, testosterone and estradiol. In the bloodstream there is good and bad cholesterol. HDL is good and lowers your risk for some health conditions, while LDL is bad and does the opposite. Finally, waxes are the last main group of lipids I am going to discuss. They contain long fatty acid chains connected to alcohols by ester linkages. Many produced by plants also have plain hydrocarbons mixed in as well. Waxes cover feathers of some aquatic birds and the lead surfaces of some plants. This is why water beads up on the leaves of many plants and why water runs off birds wings.

Segment 3: Digging Deeper Lipids Structure Function & Examples

As you can see lipids have many different roles in organisms. Phospholipids are essential to membrane structure . Wax forms water-repellent layers on leaves so they aren't soaked and they protect birds from getting wet and freezing. Cholesterol provides building blocks for hormones, is the starting hormone for other important molecules in the body such as Vitamin D and bile acids, and is important to altering the fluidity and dynamics of cell membranes. Triglycerides are essential for vitamin absorption as a lot of vitamins are fat soluble. They are also an efficient way to store energy over long periods of time (which prevents you from starving), and they provide insulation for the body. Fat has more than double the amount of energy than carbohydrates and protein, meaning they are a great source of energy. Lipids are essential to the brain structure and also signaling. Without lipids organisms would not be able to function or survive.

Carbohydrates Structure and Function

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #42

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode #42 called Unit 1 The Chemistry of Life: Carbohydrate Structure, Function, & Examples. Today we will be discussing the functional groups found in carbohydrates, the different types and functions as well as examples of carbohydrates.

Segment 1: Introduction to Carbohydrate Structure, Function, & Examples

To start off, let me explain what a carbohydrate is. A carbohydrate is one of the four major classes of macromolecules along with lipids, proteins, and nucleic acids. It consists of carbon, hydrogen, and oxygen in a 1 to 2 to 1 ratio and you might have seen variations of its chemical formula like C6H12O6. Carbohydrates have two major functional groups that are clusters of atoms with certain properties and functions. The first functional group are hydroxyls or alcohols that contain an oxygen atom bonded to a hydrogen atom. Through dehydration synthesis, they form an ether bond which is when an oxygen atom is bonded to two alkyl or aryl groups so in this case, two carbon chains. The other group are carbonyls which contain aldehydes and ketones. The main difference between the two is the positioning of the carbonyl group where aldehydes have a carbon atom bonded to a hydrogen atom and a hydrocarbon group while ketones are bonded to two hydrocarbon groups.
Carbohydrates also have four different types which are monosaccharides, disaccharides, oligosaccharides, and polysaccharides. Monosaccharides are the smallest type of carbohydrate and contain 1 sugar molecule as the prefix suggests. Disaccharides contain 2 sugar molecules while oligosaccharides are polymers that contain 3-9 sugars and lastly, polysaccharides have 10 or more sugars. Regardless of the type of carbohydrate, they contain chains of hydrocarbons that form a hexagon shaped structure.
Moving onto the functions of carbohydrates, one of them is that they are sugars which act as a source for energy. Since most cells prefer glucose as their source of energy, carbohydrates are vital to carry out basic functions. Carbohydrates also act as energy storage when the body already has enough energy to support its functions. Later once the body uses up its immediate source of energy, carbohydrates like glycogen are broken down. Furthermore, glucose is converted to ribose and deoxyribose, which are components of nucleic acids like DNA and RNA. They also tie into amino acids because they are substrates that interact with enzymes during chemical reactions.

Segment 2: Example of Carbohydrate Structure & Function

To illustrate carbohydrates in real life, examples of monosaccharides include glucose, fructose, and galactose. Although they have the same chemical formula, they differ in the structural orientation of the carbon atoms. As for disaccharides, three examples include sucrose, which is table sugar, lactose, which is the sugar found in milk, and maltose, which is created in seeds and other parts of plants. Again, they share the same formula but differ in the types of monosaccharides that they contain. However, it’s important to note that glucose is the commonality between all carbohydrate polymers because it’s a part of every disaccharide, oligosaccharide, and polysaccharide. For oligosaccharides, examples include raffinose and stachyose while examples for polysaccharides include glycogen, cellulose, starch. These 3 polysaccharides tie into the functions of carbohydrates that I discussed earlier where glycogen is the main energy storage in animals and is stored in the liver and muscles, cellulose creates the rigid, structure of plant cell walls, and starch is the main energy storage in plants. As for energy sources, an example is the human brain which only uses glucose to produce energy and function. This is why we feel light headed if we haven’t had food or sugar for an extended amount of time.

Segment 3: Digging Deeper Carbohydrate Structure, Function, & Examples

To dig deeper into carbohydrates and its connection to the chemistry of life, it shares two similar processes with the other macromolecules which are dehydration synthesis and hydrolysis. In dehydration synthesis, polymers are created from monomers by taking water out and forming covalent bonds between the monomers. Specifically for carbohydrates, it forms a glycosidic linkage. For example, when forming sucrose, the alcohol group from glucose reacts with the anomeric carbon from fructose and forms an ether bond. In hydrolysis, the opposite occurs where water is used to break the bonds in polymers and convert it to monomers. For example, animals break down glycogen into glucose when they are fasting in order to obtain energy and maintain homeostasis. Another concept it ties into is polarity which is the distribution of electrical charge in atoms and determines how atoms share their electrons and interact with other molecules. Carbohydrates are polar which means they are soluble in water. However, their solubility decreases as they become bigger so monosaccharides are very soluble but polysaccharides are not. For example, carbohydrate’s polar properties are seen in sucrose because it dissolves easily in water which is due to the attraction between the hydrogen bonds of water and the dipole-dipole interactions of sucrose. So that about sums up carbohydrates and its relevance to the chemistry of life.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Monomers and Polymers of Macromolecules

Hopewell Valley Student Publications Network — Tue, 06 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #41

Welcome to My AP Biology Thoughts podcast, my name is Arthur and I am your host for episode 41 called Unit 1: Monomers and Polymers of the Macromolecules. Today we will be discussing dehydration and hydrolysis reactions in regards to macromolecules.

Segment 1: Introduction to Monomers and Polymers of the Macromolecules

The formation and breaking of macromolecules are essential for complex life to function. We will be discussing the chemical mechanisms by which macromolecules both form and break down.
Monomers: The unit components of the larger macromolecules.
Polymers: What is formed when the monomers bond together, which are known as macromolecules.
Dehydration synthesis: A water molecule being ejected in order to allow for a monomer to covalently bond to another monomer or polymer.
Hydrolysis: A polymer splitting apart after reacting with a water molecule.
Activation energy: An energy threshold, which must be met in order for a reaction to proceed.

Segment 2: Example of Monomers and Polymers of the Macromolecules

Monosaccharides are the monomers of carbohydrates. In the presence of the necessary enzyme, a hydroxyl group is ripped off one of the monosaccharides and a hydrogen off the hydroxyl group of the other. This results in the two monosaccharides bonding together via an ether (glycosidic) bond as well as the formation of a water molecule. Conversely, this reaction can happen in reverse via hydrolysis.
The formation of triglycerides involves dehydration synthesis. An ester linkage is created between a fatty acid and a glycerol and a water molecule is released. A hydrogen is ripped of the carboxylic acid from the fatty acid and the hydroxyl is ripped off the glycerol.
Polypeptide chains form via dehydration synthesis between two amino acids. An OH is ripped off the carboxylic acid and a hydrogen is ripped off the amine group, allowing the amino acids to covalently bond as well as allowing the formation of a water molecule. This occurs many times allowing for long polypeptide chains to form, which eventually leads to proteins.

Segment 3: Digging Deeper Monomers and Polymers of the Macromolecules

The creation of macromolecules from monomers gives complex life its structure (ex. Cellulose). Additionally, the breaking down of macromolecules is essential for metabolism and the operations of cells (ex. Breaking down polysaccharides down to glucose for cellular respiration).

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Elements and Functional Groups of the Macromolecules

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #40

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode 40 called Unit 1: Elements and Functional Groups of the Macromolecules. Today we will be discussing the elements and functional groups of macromolecules.

Segment 1: Introduction to Functional groups and elements of the macromolecules

Functional Groups:

Collections of atoms that attach the carbon skeleton of an organic molecule and confer specific properties.
Each type of organic molecule has its own specific type of functional group.
Functional groups in biological molecules play an important role in the formation of molecules like DNA, proteins, carbohydrates, and lipids.

Functional groups include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl

Carbohydrates:

Elements: Carbon, Hydrogen, and Oxygen (1:2:1 ratio)

Functional Groups:

Hydroxyl
Carbonyl
Aldehyde (O= on the end of carbon chain)

Ketone ( O= in the middle of a carbon chain)

Proteins/Amino Acid:

Elements: Carbon, Hydrogen, Oxygen, and Nitrogen

Functional Groups:

Carboxylic acid
R group
Amine

Lipids:

Elements: Carbon, Hydrogen, and Oxygen (sometimes P, N, and S)

Functional Groups:

Hydroxyl
Carboxylic Acids
Esters (ester linkages)

Nucleic acids:

Elements: Carbon, Hydrogen, Oxygen, Phosphorus, and Nitrogen

Functional Groups:

Phosphate
Some nitrogenous bases have Carbonyl and Amino
Sugars have hydroxyl

Segment 2: Example of these groups in the Macromolecules

Carbohydrates:

Proteins/Amino Acid:

Lipids:

Nucleic Acids:

Segment 3: Digging Deeper Connect it to the Chemistry of life/How do these functional groups affect the macromolecules

Functional groups are specific groupings of atoms within molecules that have their own characteristic properties, regardless of the other atoms present in a molecule. They are responsible for the macromolecules functions, which play a role in the chemical processes necessary for living organisms to survive.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Water Cycle

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #39

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 39 called Unit 1 macromolecules: the water cycle. Today we will be discussing the water cycle.

Segment #1: Intro to the Water Cycle

The water cycle is one of a few biogeochemical cycles which also include the nitrogen and carbon cycles. Each cycle is unique but plays an important role in sustaining life. In the water cycle, water vapor is made when the sun causes evaporation in bodies of water such as the ocean by heating the water into vapor. Snow can also be vaporized in the process called sublimation. This vapor is moved by the winds to other parts of the world. When it reaches air that is cooler, it condenses into precipitation (which is seen as rain or snow). It then returns to the ocean or the land. If it returns to the land, it eventually travels tco plants or other bodies of water that will eventually get it back to the ocean. If it is absorbed by plants, the water is used for photosynthesis or can be lost in transpiration.

Segment #2: Digging Deeper into the Water Cycle

Since the water cycle is a cycle, it is difficult to find examples of it. However, we can provide examples for the different steps of the cycle. An example of evaporation would be when the sun warms water in a pond enough to change its state from liquid to gas. This can happen in any body of water, such as oceans, as previously mentioned, lakes, or rivers. After evaporation, the water molecules are in the sky. Precipitation takes many forms, but its most recognizable form is rain. Precipitation is any type of water that falls from the sky, so It can also be in the form of snow, hail, freezing rain, or sleet. The last step of the water cycle is collection, which is when water goes back to its original source. One example of this is if it rains on a lake that leads to an ocean. This would carry the water back to the ocean, its original source, to be evaporated as the cycle continues. The water cycle is constant, which means that as some water particles are being evaporated, others are in the form of precipitation, and still others are being collected.

Segment #3: Making larger Connections with the Water Cycle

The water cycle helps to regulate temperatures in both organisms and on earth. One example of this is when oceans heat up more slowly than air since the water absorbs the light energy. Hydrogen bonds make this possible because it takes more energy to break the hydrogen in water to convert the liquid into a gas than to heat up gas that is already a gas. This property keeps the temperature on the earth more stable. Evaporation also helps animals and plants too cool down. Evaporation carries heat energy away from the organism which provides cooling. Additionally, water’s expansion when it freezes is also caused by hydrogen bonds. When water freezes the hydrogen bonds move outward to 90 degree angles which causes the water molecules to be further apart. This also makes it less dense which is why ice floats on water. Because of this, life is still able to survive under ice in the ocean since the ice is only on the top.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Phosphorus Cycle

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #38

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode 38 called The Phosphorus Cycle. Today we will be discussing what makes up the Phosphorus Cycle, its significance, and how it fits into the greater topic of the Chemistry of Life.

Segment 1: Introduction to The Phosphorus Cycle

We will begin by discussing what exactly phosphorus is and why it is so important to life as a whole
Phosphorus is an essential nutrient found in the macromolecules of humans and other organisms including their DNA
Key part of the phospholipids that form our cell membranes
In aquatic ecosystems, phosphorus is actually a limiting nutrient (one that is the most scarce) which limits growth
The phosphorus cycle itself is a very slow process, and most of it exists in nature as the ion PO4 3-
Phosphorus can be found in fertilizers, and when it is carried off in lakes or oceans, it can cause the overgrowing of algae, or eutrophication which depletes the body of water of oxygen which is detrimental to the ecosystem overall
It isn’t available for plants to use because most phosphorus is locked up in sediments and rocks, and the phosphorus in the soil isn’t available for plants
Several reversible pathways are formed which is what the availability of phosphorus in soil depends on:
Bacteria: It converts plant-available phosphate into organic forms that are then not available to plants
Adsorption: Inorganic (and available) phosphorus can be chemically bound (adsorbed) to soil particles, making it unavailable to plant
pH: Inorganic phosphorus compounds need to be soluble to be taken up by plants which depends on the acidity (pH) of the soil, so if soils are less than pH 4 or greater than pH 8, the phosphorus starts to become tied up with other compounds, making it less available to plants
Many farmers replenish phosphorus through the use of phosphate fertilisers which is obtained by mining deposits of rock phosphate

Segment 2: Example of The Phosphorus Cycle

Here is a picture of what the Phosphorus Cycle looks like
First, since phosphate compounds are found in sedimentary rocks, the rocks weather, and the phosphorus they contain slowly leach into the soil and surface water
These compounds are taken up by plants and then transferred to the animals that eat these plants
When plants and animals excrete wastes or die, phosphates can be consumed by detritivores or returned to the soil
Phosphorus-containing compounds may also be carried in surface runoff to rivers, lakes, and oceans, where they are taken up by aquatic organisms
When phosphorus-containing compounds from the bodies or wastes of marine organisms sink to the floor of the ocean, they form new sedimentary layers
Over long periods of time, phosphorus-containing sedimentary rock may be moved from the ocean to the land by a geological process called uplift
When plants and animals die, decomposition results in the return of phosphorus back to the environment via the water or soil

Segment 3: Digging Deeper Into Phosphorus Cycle

The Phosphorus Cycle fits into the greater picture of the Chemistry of Life in terms of the fact that it is required for all organisms to live and grow since it is an essential component of ATP (energy complex), the structural components holding DNA and RNA together, cellular membranes, and other critical compounds
Phosphorus forms parts of important life-sustaining molecules that are very common in the biosphere, and is in fertilizers, rocks, and minerals as well

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Carbon Cycle

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #36

Segment 1: Introduction To The Carbon Cycle

Carbon cycle Def

The way nature reuses carbon atoms
The process in which carbon travels from the atmosphere into organisms and the Earth and back into the atmosphere

Background info about cycle

Carbon in constant state of movement from place to place and stored in reservoirs - moves between these reservoirs through photosynthesis, burning fossil fuels, respiration, etc.

Cycle = cyclic - if you start at one reservoir, you will get back to that same reservoir
Earth = closed system - amount of carbon on the planet never changes
Nature keeps carbon levels balanced - amount of carbon released from reservoirs equal to amount obtained by same reservoirs

Steps

Carbon moves from atmosphere to plants - carbon first came from frequent volcanic activity and asteroid impacts - carbon attached to oxygen in CO2
For photosynthesis, CO2 is pulled from the air by plants to help in the process of producing food in the form of glucose which the plants consumes
Carbon moves from plants to animals through food chains - animals eat these plants that have this carbon that the plants got from atmosphere
Carbon moves plants and animals to soil - bodies, wood, leaves decay - carbon released as production from decomposition reaction go into ground - buried sometimes and turned in fossil fuels in millions of years
Fossil fuels burned as human energy resources, carbon is then moved to the atmosphere as carbon dioxide - every year, 5.5 billion tons of carbon is released by burning fossil fuels and around 60% of this amount stays in the atmosphere while remainder becomes dissolved in seawater
Carbon can get to atmosphere by respiration - release carbon dioxide as animals exhale - producers use energy from sunlight to make bonds between carbon atoms; animals break these bonds to release the energy they contain - turns carbon compounds into single carbon units - released into atmosphere as carbon dioxide
Carbon could be released back into the atmosphere - volcanoes erupt, fires blaze, solid waste
Carbon moves from the atmosphere to bodies of water - bodies of water absorb carbon from the atmosphere - dissolved into water
Oceans release CO2 - carbon dioxide from atmosphere comes into contact with ocean water - reacts with water molecules to form carbonic acid
When carbonic acid > carbon dioxide amount in the atmosphere, some carbonic acid may be released into the atmosphere as carbon dioxide

Segment 2: Getting Into Specifics: The Carbon Cycle

Geosphere
Geological component of the carbon cycle - operates slowly
Important determinant of amount of carbon in the atmosphere
Of the carbon stored in geosphere, 80% of it is limestone and its derivatives which form from the sedimentation of calcium carbonate stored in the shells of marine organisms; other 20% is stored as kerogen (organic matter in sedimentary rocks) - kerogen formed through the sedimentation and burial of terrestrial organisms under high heat and pressure
How its released into atmosphere
Carbon dioxide could be released during the metamorphism of carbonate rock - recycled into the Earth’s mantle at convergent boundaries.
Through volcanoes and hotspots
Removed by humans through extraction of kerogens in form of fossil fuels - burned and emit carbon
Ocean reservoir - biological pump
Ocean divided into surface layer and mixed layer 300 feet below
Dissolved inorganic carbon in the surface layer exchanged rapidly with the atmosphere - deep ocean contains more carbon mainly due to its larger volume - exchange of carbon between these two layers of the ocean is extremely slow
Carbon enters the ocean through the dissolution of atmospheric carbon dioxide - small part of turned into carbonate; can also enter through rivers as dissolved organic carbon
It is converted by organisms into organic carbon through photosynthesis and can then be either exchanged throughout the aquatic food chain or end up in the deeper carbon rich layers of the ocean as dead soft tissue or in shells as calcium carbonate
The carbon can stay in deep layer for a while before being deposited as sediment or returned to the surface of the water
When the aquatic organisms that contain carbon die and decompose, they also release carbon dioxide back into the water
Terrestrial biosphere
Most carbon is organic - ⅓ stored in inorganic forms like calcium carbonate
Carbon uptake in the terrestrial biosphere is dependent on biotic factors - follows a diurnal and seasonal cycle
Carbon can leave reservoir by being exported into the ocean or rivers by erosion or into the atmosphere through soil respiration (carbon in soil being respires by soil organisms)
Fast carbon cycle
Present in biosphere - complete within years
Moves carbon from atmosphere to biosphere to atmosphere
Involves short-term biogeochemical processes between the environment and living organisms in the biosphere
Consists of the movement of carbon between the atmosphere and terrestrial and marine ecosystems, and soils and seafloor sediments
Involves the annual and seasonal processes of photosynthesis, vegetative growth and decomposition
Slow carbon cycle
Can take millions of years to complete
Moves carbon through the Earth’s crust between rocks, soil, the ocean, and the atmosphere
Includes longer geochemical processes that involve the rock cycle - weathering of rocks can take millions of years
Exchange that takes place between the ocean and atmosphere can take centuries
Mountain building is what returns this geological carbon to Earth’s surface - takes hundreds of thousands of years
Deep carbon cycle
The movement of carbon through the Earth’s mantle and core
Deep carbon cycle enables carbon to return to Earth - maintains living organisms of Earth

Segment 3: Digging Deeper Into the Carbon Cycle

Carbon - building block for life and is known as such due to its ability to form complex macromolecules
The backbones or components for macromolecules is carbon - the carbon atom has properties that enable it to form covalent bonds to as many as 4 different atoms, making this element versatile and ideal to serve as the basic structural component of macromolecules
Proteins
Made up of an amino group (has C), a carboxylic group (has C), and a side chain (made up of C) - all connected by and bonded to a carbon atom
Function - allow metabolic reactions to take place, they provide a source of energy, they assist in cellular and tissue repairs, they form blood cells, they catalyze reactions, etc.
Lipids
Made up on hydrocarbon fatty acid tails
Function: allow for energy storage, insulation, cellular communication and protection
Carbs
Made primarily of a carbon chain and an aldehyde and a ketone, which both also consist of carbons
Function: enable humans to attain their energy and fuel that they need to function physically and mentally
Nucleic acids
Consist of carbon in the sugar phosphates that make them up
Function: hold the instructions needed for an organism to develop, survive, and reproduce; protein synthesis
Carbon/CO2 important aspects
Allow photosynthesis to be possible - assures that all heterotrophs and autotrophs don’t die
Major part of cellular respiration
Carbon dioxide and greenhouse gases in general keep our planet livable by holding onto some of Earth’s heat energy so that it doesn’t all escape into space - enables heat to be retained in the atmosphere
Human impacts on carbon cycle
Carbon cycle normally works to ensure the stability of variables such as the Earth’s atmosphere, the acidity of the ocean, and the availability of carbon for use by living things
Humans, by burning fossil fuels, deforestation, geological and carbon sequestration, and by using limestone to make concrete have caused a drastic increase in the rise of carbon dioxide in the atmosphere
More and more carbon in the air = more heat energy being absorbed and global temperatures rising and rising and weather is changing all over and becoming more extreme
Ocean acidification - reducing the amount of carbonate that coral and plankton need and killing off aquatic life not suited for lower pH’s
No true stability; balance of cycle and amounts of carbon in different reservoirs messed up
Great amount of carbon in atmosphere (affects ecological aspects) → this carbon dioxide taken in by plants, the ocean, and aquatic organisms → ocean acidification; plants attaining too much CO2 - thicken their leaves and photosynthesis less → heterotrophs could eat plants with excessive amounts of carbon or inhale it from atmosphere → too much carbon dioxide can kill animals since it can decrease the amount of oxygen reaching the body

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Properties of Water

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #35

Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #35 called Unit 1 Chemistry of Life: Water Properties. Today we will be discussing how the chemical makeup of water gives it unique properties that allow it to foster life.

Segment 1: Introduction to Water properties

Water consists of 2 hydrogen atoms covalently bonded to a single oxygen atom. The electronegativity of the oxygen makes the molecule partially positive by the Hydrogen atoms and partially negative by the oxygen atom. This creates a polar molecule that can hydrogen bond to other molecules. This makeup is key to many of water’s unique properties.

Segment 2: Example of Water properties

The first property of water that is unique is its high specific heat

Takes a lot of energy to increase the temperature of water
This is bc pf H bonds, need enough E to break all H bonds and H bands are strong

Ice floats

This is unique
Solid float when less dense than liquid
Lattice structure created between max amount of H bonds cause water to expand, making it less dense
Seen in glaciers or everyday life

Adhesive and Cohesive

Cohesion-resist coming apart
Adhesion-attraction between water and solid surface
Strong H bonds
Can adhere to anything because partial charge
In stems of plants

Solvency

Can dissolve anything with partial or full positive or negative charge and breaks apart
The positive and negative charges of water attract charges in other compounds, pulling them apart into smaller molecules. Example: a block of salt gets pulled apart into Na+ and
Cl- ions

Segment 3: Digging Deeper water properties

Ice floats- water would freeze and glaciers are home to arctic animals

Adhesive and cohesive= capillary action and plants getting water solvency. It means that wherever water goes, either through the air, the ground, or through our bodies, it takes along valuable chemicals, minerals, and nutrients, Water serves to suspend the red blood cells to carry oxygen to the cells. It is the solvent for the electrolytes and nutrients needed by the cells, and the solvent to carry waste material away from the cells.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Water… The Universal Solvent

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #34

Welcome to My AP Biology Thoughts podcast, my name is Morgan Bernstein and I am your host for episode #34 in (Unit 1 Macromolecules: (Water, the Universal Solvent)). Today we will be discussing the properties of water that make it the universal solvent.

Segment 1: Introduction to water as a universal solvent

Water is a molecule- two hydrogen atoms and one oxygen atom, chemical formula of H2O.
Bonds= chemical properties
Bonds within water are covalent bonds (extremely strong so a lot of energy to break a water molecule apart)
Important bond with water is hydrogen bond- between water molecules instead of within.
Occurs when a hydrogen is bonded to electronegative atoms, Nitrogen, Fluorine, Oxygen.
The reason this bond is so special is because of the polarity of water molecules. electrons are not shared equally between atoms.
Hydrogen atoms are partially positive where oxygen atoms are partially negative. When it joins with another water molecule, the partially negative oxygen atom gravitates towards the partially positive hydrogen atom, forming our hydrogen bond.
Lastly, we need to know what a solvent is in order to understand why water is known as the universal one. A solvent is a substance that is able to dissolve another substance, in order to make a solution. Water is known as the universal solvent

Segment 2: Example of solutes in water

soluble= salt, sugar, food coloring and coffee.
insoluble= oil, flour and sand.

The partially positive hydrogen atoms and partially negative oxygen atoms in water that make it polar are also the reason that so many substances are soluble in water.

In salt, the partially negative chlorine atom in salt will automatically be attracted to the partially positive hydrogen atom in the water. Vice versa, the partially positive sodium atom will be attracted to the partially negative oxygen atom.
Then the weak hydrogen bonds break and salt can dissolve

On the other hand, something like oil will never be able to dissolve in water, because it is nonpolar. sharing of electrons within oil is even, no partially positive or partially negative charge.

Not attracted to either part of the water molecule and the hydrogen bonds don't break, two substances never mix

Even though it is not able to dissolve nonpolar substances, water is known as the universal solvent because it is able to be a solvent for more solutes than any other substance

Segment 3: Digging Deeper into the properties of water

Water as a universal solvent has many other connections to our unit of macromolecules and biology in general.

One variable that affects the solubility of water is temperature.

Increased temperature means higher kinetic energy means higher solubility. Salt dissolves more in boiling water than in ice.

Another important fact when considering solubility is saturation. When all bonds are formed between water and salt, solution is saturated and no more dissolves.

When talking about macromolecules, water plays an important role as well.

Carbs- soluble, but less soluble as becomes polysaccharide
Lipid- soluble polar glycerol head but nonpolar insoluble fatty acid tail. Overall mostly insoluble.
Proteins-depends on shae and r group
Nucleic acids- mostly soluble, dna and rna

Adhesion- water sticks to other things ex leaf

Cohesion- water sticks to itself ex on penny

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

The Nitrogen Cycle

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #37 Nitrogen Cycle

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #37 called Unit #1 Chemistry of Life: Nitrogen Cycle.

Segment 1: Introduction to the Nitrogen Cycle

The nitrogen cycle is a complex cycle that circulates nitrogen on Earth. Nitrogen is extremely important for life because it plays roles in the production of proteins and nucleic acids. Because of this it is essential for all life. On earth, 78 percent of the atmosphere is nitrogen. Despite this abundance, most organisms are unable to use nitrogen in the form of gas. This is where the nitrogen cycle comes in. The steps of the nitrogen cycle are nitrogen fixation, nitrogen assimilation, ammonification, nitrification, and denitrification. Because this is cyclical, there is no real “first” step to the nitrogen cycle. Instead, the nitrogen is continuously cycling in through its various forms. Nitrogen first gets into the soil by precipitation. The water carries nitrogen into the soil. The nitrogen then finds its way to the bacteria that live on the roots of plants. Then the nitrogen is combined with hydrogen at the roots to make ammonium. This process is called nitrogen fixation. This can also be done by lightning in the atmosphere. After the nitrogen has become a part of ammonium, nitrifying bacteria add oxygen in order to create nitrites. This process is called nitrification. Unlike ammonium, the nitrites are not toxic. After this, once again more nitrifying bacteria come in and turn the nitrites into nitrates. After this process, the plants can finally absorb the nitrates. The process of plants absorbing the nitrates is called assimilation. Still, all of the nitrates are not used for plants. Some of the nitrates can go to denitrifying bacteria which turn the nitrates back into the atmosphere. This process is called denitrifying. Also, after the plants have absorbed the nitrates, then animals eat the plants with nitrogen in them in order to get nitrogen. Once the animals leave waste or die, the get broken down by decomposers which allow for ammonification to occur once again where the nitrogen can go back into the cycle as ammonium.

Segment 2: Example of Nitrogen Cycle

Now we can look at how specific plants and animals use nitrogen or are a part of the nitrogen cycle. Simple examples of this can come from primary consumers which take the nitrogen directly from the plants. For example, rabbits are primary consumers who get their energy from plants. From plants, they also get nitrogen. A rabbit might eat plants like lettuce, beans, broccoli, and even some flowers. All of these plants, in order to live, will have nitrogen in their cells. After the rabbit eats one of these plants, the nitrogen gets transferred into their system. Then they can use the nitrogen for proteins or nucleic acids which are essential to their survival.

Another specific exam can be of humans. Humans eat plants and animals frequently. Nitrogen comes from both of these food sources. When humans eat vegetables, the vegetables were once plants that absorbed nitrogen through the soil. Then when we eat the plants, we absorb that nitrogen. Also, when humans eat meat, the animal had at one point eaten plants with nitrogen in them which allowed them to have nitrogen. Then we absorb that nitrogen from the animal.

Segment 3: Digging Deeper Into the Nitrogen Cycle

Nitrogen is extremely important for all living things. This is because nitrogen is involved in many essential processes. For this reason, the nitrogen cycle has a big part to play in the chemistry of life. Specifically, out of the four macromolecules, nitrogen is involved in the formation of proteins and amino acids. Proteins are arguably the most important macromolecule as they serve a variety of functions such as in the creation of enzymes, and are necessary for the function and structure of the body’s tissue. Also nucleic acids are arguably the second most important macromolecule. This is because nucleic acids are the bases for DNA and RNA which provide the storage and expression of genetic information which also tell proteins what to do. For this reason the nitrogen cycle is extremely important especially for biochemistry.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

“Ice Flow” Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Polarity of Water and Hydrogen Bonding

Hopewell Valley Student Publications Network — Mon, 05 Apr 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 1 Episode #33

Welcome to My AP Biology Thoughts podcast, my name is Alex and I am your host for episode 33 called Polarity of Water and Hydrogen Bonding. Today we will be discussing the importance of water polarity and hydrogen bonding in biology.

Segment 1: Introduction to Hydrogen Bonds

What is water polarity and what are hydrogen bonds? Water is polar because of its asymmetrical structure and uneven distribution of electrons. The structure of water is asymmetrical because of electron pairs within the oxygen, causing the O-H bonds to be pushed down towards each other. The uneven distribution of electrons is caused by the oxygen having a higher electronegativity, pulling in the bonded electrons more strongly than the hydrogen. This causes a partial negative charge on the oxygen side, and a partial positive charge on the hydrogen side. Hydrogen bonds happen when a positively charged hydrogen of one molecule has a polar covalent bond with a Nitrogen, Oxygen, Fluorine, or Chlorine of another molecule.

Segment 2: Example of Water Properties

An example of these properties are the cohesive property of water. This is caused by the hydrogen bonding in the water, creating an attractive force between the molecules, this allows water molecules to clump together, which gives water its surface tension and adhesion to other molecules.

Another example of water’s polarity is its high heat of evaporation. The relatively strong hydrogen bonds are able to strongly hold the water molecules together. This makes it take a lot of energy to break the bonds between water molecules, and evaporate the liquid. This is an important property of water as it allows water to present on most of Earth no matter the current temperature or climate.

Segment 3: Making Connections

The polarity of water and hydrogen bonding is an essential part of biology. These two properties are responsible for so many properties of water, which are extremely essential for life to exist. Ice floats because of the hydrogen bonds in water, but if ice sank then many aqueous ecosystems would die in the winter as the ice would freeze the entire lake instead of the surface. Water’s polarity also gives it a very high specific heat capacity, which allows organisms to effectively regulate their body heat through releasing water from their systems. The polar structure of water is essential for all living organisms, especially because many organisms are primarily composed of water. Water’s polarity leads to many more properties, such as being a universal solvent, as well as the universal base and acid, all of which are essential properties to all living things.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Connect with us on Social Media

Twitter @thehvspn

Global Warming and Climate Change

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #32

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode 32 Unit 8 Ecology: Global Warming and Climate Change. Today we will be discussing Global warming, climate change and how they affect environments and species.

Segment 1: Introduction to Global Warming and Climate Change

Global warming is the increase in temperature through many years largely due to the effects of greenhouse gases being released into the atmosphere. Though they are similar, climate change is slightly different from global warming. Climate change refers to the changing climate over a period of time. This means changes in precipitation, temperature, and wind patterns. Climate change and global warming is mostly because of human activity when they release carbon dioxide, pollutants, and greenhouse gases into the atmosphere. These gases absorb sunlight and radiation that bounce off of the Earth’s surface and increase the global temperature. Global warming then causes other climate change such as increased precipitation. When the global temperature is increased, this allows more evaporation to occur and the atmosphere to hold more moisture. Also, as arctic regions melt, water levels rise promoting even more evaporation. As a result, precipitation becomes much more intense in many regions. The increase in temperature also causes changes in wind patterns. As temperatures increase in some regions, winds become slower.

Segment 2: Example of Global Warming and Climate Change

Global warming and climate change has disastrous effects on the environment and many species. Global warming affects some regions more directly than others. For example, arctic regions like Greenland are heavily affected. In Greenland, as the air and water temperature increase, there are disastrous effects like losing sea ice, the melting of the ice sheet, and habitat destruction of species that live there. On average, Greenland loses an average of 234 billion tons of ice mass per year. This is a drastic change because in the 1990’s this was only 25 billion tons lost per year. This change in Greenland affects species like polar bears. Polar bears rely on sea ice in order to hunt seals. Because the sea ice has been so drastically reduced, polar bears have had to adapt to this change but have been struggling to do so. It’s now predicted that the populations of polar bears will drop by 30% in the upcoming decades. This would cause the total number of polar bears to become under 9,000. Many other species are also affected. To start, Moose populations are heavily affected by climate change. As temperatures rise, winter ticks, parasites that often feed on the blood of moose, increase in population. As the population of winter ticks increase, a higher number of them end up on moose. There can be up to tens of thousands of these ticks on one moose. When there are many ticks on one moose, the moose often die especially when they are young. Another species affected are salmon. Salmon require cold and fast flowing rivers. As temperatures increase, the water temperature increases and the flow of rivers can change. This affects how they interact with their environment. Also, similar to the moose, the parasites that feed off of salmon increase in population which causes them to die off at higher rates. Another species that is affected are the sea turtles. When the temperatures increase this causes sea levels to rise, increased precipitations, and more extreme storms. This causes nesting and foraging sites to become unsuitable and makes it harder for the sea turtles to survive. For one last example, giant pandas are another animal heavily affected by global warming and climate change. As temperatures increase, the main food source for pandas, bamboos, are becoming wiped out. Because pandas are losing their main food source, they are dying off as well.

Segment 3: Digging Deeper Global Warming and Climate Change

Global warming has direct effects on ecology. Ecology refers to organisms, their populations, and how they interact with their environment. Global warming and climate change directly affects all levels of ecology from individual organisms, populations, communities, and ecosystems across the Earth. Global warming can affect entire ecosystems as temperatures increase, storms become more intense, arctic regions melt, and sea levels rise. This of course would affect the way organisms interact with their environment.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Invasive Species

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #31

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode 31 called Invasive Species. Today we will be discussing invasive species. Before I start, I’d like to give credit to several different sources including the National Wildlife Federation, National Geographic, Eric Guise’s AP Biology videos, as well as UC Riverside Center For Invasive Species Research, New York Invasive Species Information, Wikipedia, National Geographic, the Global Invasive Species Database, and last but not least, the Wisconsin Department of Natural Resources.

Segment 1: Introduction to Invasive Species

Invasive species description

Non-native, spread rapidly, economic/environmental harm
Adapts to new area and reproduce quickly - cause some type of harm
Spread by human activities - pest control, traveling from one place to another, people releasing pets into the wild (goldfish and burmese python), animals and pets could escape from humans
Impacts and reasons for impacts
Invasive species = no natural predators or control - no limiting factors
They can outcompete native species for same resources
They could prey on many native organisms
Affects smaller ecosystems and food chains in negative ways
Biodiversity would be lessened
They could change the abundance of certain significant species important to other organisms
Native species would be defenseless new invader with no limitations
Invasive species could carry or cause disease, prevent native species from reproducing
They can change native food web
Abiotic conditions impacted - invasive plants affect water quality, tree cover, and can create fuel for wildfires

Segment 2: Examples of Invasive Species

Brown Tree Snake

Spread through travel
WW2 - snake transported from South Pacific to Guam - stowaway in ship cargo or in landing gear of aircraft
Could have been used to suppress the rat populations in Guam which were very high before 1950s
Snakes - no natural predators+abundant prey = exponential growth
Snake has caused great damage to forests of Guam - decimated birds and herpetofauna
Local extinction of half of over Guam’s native bird and lizard species, ⅔ of Guam’s native bat species - reduced pollination by lizards and birds - reduced native plant regeneration and coverage
Impacted local health and economy
Venomous - health hazard to infants and young children
Increased disease carried by insects - kept in check by Guam’s native native lizards and birds - dengue fever and infant salmonellosis
Cause constant power outages - affect private, commercial, and military activities
Agricultural pest - insects increase in population due to killing off of birds and lizards; insects reduce crop yields
Asian Tiger Mosquito
Native to southeast Asia - spread along major transportation routes - commercial movement of scrap tires - spread to over 900 countries in 26 states (now in south central US)
Apparent in Europe, Caribbean, Africa, and the Middle East
Introduced to California in shipments of ornamental bamboo from south China and were found at the Port of Houston in 1985 in a shipment of used tires
Domestic in Torres Strait around Australia and Queensland and in Nigeria
Outcompeted/ridden off species with similar breeding habitats - yellow fever mosquito in Florida and Ae. Guamensis in Guam
They transmit pathogens and viruses - yellow fever, dengue fever, usutu virus (humans), roundworms and heartworms (animals), wolbachia infection (arthropods) - affects over 40% of arthropods that contract it
Northern snakehead
Native to China, possibly to Korea and Russia too
Entered US when aquarium owners discarded them into local waterways after attaining them from foreign markets or within US
Could have been released into US waterways for fisherman - fish is important in Asia
Small prey threatened by feeding juvenile snakehead - zooplankton, larvae, small; adults prey on fish, amphibians, reptiles, birds, mammals - effect ecological conditions and biodiversity
Kudzu
Native to China, Japan, and India
Introduced to NA in 1876 in Japanese pavilion at Philadelphia Centennial Expositions and in Japanese pavilion at New Orleans exposition in 1884
Promoted by government for erosion control and as drought tolerant, nitrogen fixing legume
Thousands of acres planted by CCC for hillside stabilization projects
Aggressive - found in over 30 states
Kill plants by smothering them under blanket of leaves; break branches; uproot trees; eliminate light availability for trees - kudzu grows on top of things to maximize light amount they receive
Ability to outcompete (need little nitrogen, acquire resources quickly, etc.) = formation of monospecific plant communities that alter plant communities
Economic liabilities - millions per year in lost forest production for southern commercial timber producers

Segment 3: Digging Deeper Into Invasive Species

Methods of control - manual, chemical, biological, cultural, mechanical
Biological
Using living organisms to reduce seed production and vigor of invasive populations
Control organisms come from native range of the target species and require period of study to ensure they remain specific to target population rather than harm the native species
Biological control time consuming, doesn’t always work
Worked with galerucella beetle used to control European perennial purple loosestrife
Chemical
Using pesticides and herbicides to curb invasive species growth - varies depending on target species and its size, growth stage, and affected species - not done with rare species, etc.
Manual
Hand pulling, digging, flooding, mulching, burning, removal of alternate hosts, and destruction/removal of nests, egg masses or other life states - persistence necessary
Not used on pervasive species
Mechanical
Cutting, girding, mowing, chopping, and making barriers using tools or machines - better with chemicals
Cultural
Manipulation of environment - replacement of restoration of plant community
Invasive species can sometimes be more of a positive over time
Ex: Study in Proceedings of National Academy of Sciences - researcher looked at seaweed Gracilaria vermiculophylla which spread from Japan with export of oysters
Foul up fishnets and boat propellers and remove O2
Provides habitat and shelter for native animals - invertebrates in mud, crab, shrimp, fish, etc.
Denmark - same algae lived with habitat forming animals, not harmful for mussels/seagrass, provide habitats for invertebrates
Summary - relation to ecology
Basically talk about how they harm natural resources, cause competition, extinction - changes in interactions with environment
Decreased populations = more decreases
Cause of 6th extinction

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Simpson Diversity Index

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode # 30

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode 30 called Unit 8 Ecology: Simpson Diversity Index. Today we will be discussing how diversity in an ecosystem can be measured mathematically on a scale from 0 to 1.

Segment 1: Introduction to Simpson Diversity Index

The Simpson Diversity Index measures the diversity in a habitat while taking into account the number of species present and the abundance of organisms in each species. There is a simple equation to this Index which will give you a number from 0 to 1 as your answer, 1 being infinite diversity, and 0 being no diversity at all.

Segment 2: Examples of Simpson Diversity Index

The Simpson Diversity Index is important because it can help measure how diversity changes in response to a natural event or human impact. For example, scientists could measure the diversity of a habitat before and after a forest fire, and analyze the Simpson Diversity index to understand how the diversity was affected by the fire. Biodiversity in a habitat is important because each species has a specific role, and a significant decrease in the number of species could have a detrimental effect on the habitat. Keystone species are especially important to a habitat because a majority of species rely and depend on them. If the keystone species gets wiped out, it is more than likely for the Simpson Diversity index to drastically decrease.

Segment 3: Digging Deeper into Simpson Diversity Index

When natural selection results in adaptive radiation, the Simpson diversity index can change drastically. For example, Darwin’s Finches created 13 different species which is an increase in the biodiversity of the ecosystem. Another example is extinction. When a natural disaster causes the diversity index to decrease, many niches are left unoccupied, and the habitat can fall apart leading to extinction.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Symbiotic Relationships

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #29

Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #29 called Unit 8 Ecology: Symbiotic Relationships.. Today we will be discussing the 3 symbiotic relationships in nature.

Segment 1: Introduction to symbiotic relationships

Symbiosis is any type of a close and long-term biological interaction between two different biological organisms, be it mutualistic, commensalistic, or parasitic. The organisms, each termed a symbiont, may be of the same or of different species

Segment 2: Example of symbiotic relationships

Mutualism: 2 organisms benefit from one another
Example: oxpecker (a kind of bird) and the rhinoceros or zebra. Oxpeckers land on rhinos or zebras and eat ticks and other parasites that live on their skin. The oxpeckers get food and the beasts get pest control.
Commensalism: 1 organism benefits and other organism is not impacted
Example :Remora fish have a disk on their heads that makes them able to attach to larger animals, such as sharks, mantas, and whales. When the larger animal feeds, the remora detaches itself to eat the extra food.
Parasitism: 1 organism benefits and the other is negatively impacted
Example: Moose and ticks-In such numbers the ticks drain so much blood that the host moose can become anemic and malnourished

Segment 3: Digging Deeper into symbiotic relationships

How does this topic fit into the greater picture of ecology?

Ecology is all about organisms relationships with each other and the environment
Helps classify how they all fit in with each other
because they are a major driving force of evolution- coevolution-evolve together. This networking and cooperation among species allows them to survive better than they would as individuals.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Density Independent vs Density Dependent

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #28

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode #28 called Unit 8 Ecology: Density Independent vs Density Dependent limiting factors.. Today we will be discussing exactly that, limiting factors in an ecosystem that are considered density independent and density dependent.

Segment 1: Introduction to Density Independent vs Density Dependent

Population density- the number of organisms within a given area or ecosystem (how crowded)

Low density ecosystems- organisms spread out (country/rural)

High density ecosystems- lots of organisms in little space (New York City)

Organisms can't grow exponentially or else the earth would be covered in all sorts of animals and population, so we need something that limits the population

Limiting Factor- something in an ecosystem that helps contain a population’s size by slowing or stopping growth, (biotic or abiotic)

Density dependent factors- higher the density of the population, the higher the impact of the limiting factor will be. When there are more organisms, more will be affected

Density independent- regardless of the density (crowdedness/ number of organisms) the limiting factor will decrease the population the same amount.

large population and small population would be equally impacted

Segment 2: Example of density dependent and density independent limiting factors

What are these limiting factors?

Density dependent factors are food, shelter, water, parasites, and predators.

There is competition for these resources so in a larger population, more animals are competing for these factors, and more animals will NOT have access to them
A smaller population has less competition, and will not suffer as much from this lack of resources.

The same goes for parasites and predators.

Big population has more prey for the predators to feed on and more animals the parasites can attach to
A small population will not be as impacted by this type of limiting factor.

Density independent limiting factors - fire, flood, hurricanes, and pollution. natural disasters

limit populations regardless of size

EXAMPLE: In a large or small ecosystem which has just experienced a hurricane, many of the organisms are going to die off, and the population size will decrease. If the hurricane kills 50% of the population, it is going to have the same impact in both ecosystems. Obviously with a larger population there will be a larger number of organisms who are killed, but both populations will be reduced to half of their original size.

Segment 3: Digging Deeper into the significance of limiting factors

Population growth rates- exponentially increases continuously, getting larger and larger without decreasing (population without any limiting factors)

logistical growth population - carrying capacity, do experience limiting factors.

limiting factors lower the carrying capacity of a population and stop the growth of that population

Cause resource partitioning, where organisms occupy various parts of the ecosystem to avoid competition.

Density dependent factors such as food, water, and shelter often cause competition among organisms in an ecosystem

Lastly, limiting factors are influenced by humans in many ways.

We have a direct impact on limiting factors such as shelter and food - building houses or deforestation.
We also can have an indirect impact through water quality and pollution by other actions.

Density independent limiting factors can lead to density dependent limiting factors. Fire started by humans has a direct effect on the ecosystem, but the aftermath of destroyed shelters also has an effect.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Logistic vs Exponential Growth

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #27

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode 27 called Unit 8 Ecology: Logistic VS Exponential Growth.

Segment 1: Introduction to Logistic and Exponential Growth

Logistic Growth: populations grow as fast it can with the limited resource it has to support the growth, making the population growth dependent on the availability of resources, when resources start to decrease or come to a stop, that is called carrying capacity

Exponential growth may happen for a while, if there are few individuals and many resources. But when the number of individuals gets large enough, resources start to get used up, slowing the growth rate. Eventually, the growth rate will plateau, or level off, making an S-shaped curve. The population size at which it levels off, which represents the maximum population size a particular environment can support, is called the carrying capacity, or K
Any kind of resource important to a species’ survival can act as a limit, causing the carrying capa For plants, the water, sunlight, nutrients, and the space to grow are some key resources. For animals, important resources include food, water, shelter, and nesting space. Limited quantities of these resources results in competition between members of the same population, or intraspecific competition (intra- = within; -specific = species).

Exponential Growth: resources are unlimited, populations grow as fast as they can, J-shaped curve, the populations faces no predators, like an invasive species

Segment 2: Example of Logistical and Exponential Growth

Yeast (logistic growth)

a microscopic fungus used to make bread and alcoholic beverages,
can produce a classic S-shaped curve when grown in a test tube.
In the graph shown below, yeast growth levels off as the population hits the limit of the available nutrients.
(If we followed the population for longer, it would likely crash, since the test tube is a closed system – meaning that fuel sources would eventually run out and wastes might reach toxic levels).

Spotted Lantern Fly (an Invasive species) or Bacteria

The Spotted Lanternfly is an invasive species that destroys fruit crops, trees and plants by hopping from plant to plant, crop to crop, and tree to tree.
Although native to regions in China, India, and Vietnam, it was first detected in Berks County, Pennsylvania in 2014.
Since then, Pennsylvania vineyards have seen considerable damage in high infestation areas and the Mid-Atlantic states of Delaware, Maryland, New Jersey, Virginia and West Virginia have also suffered from its presence.
Insecticides are effective at killing the insect on grapevines, but they are expensive and of limited use because of constant re-infestation from the Spotted Lanternfly dispersing from wild hosts to surrounding vineyards.
They are constantly growing due to them not having predators to kill them off, them adjusting perfectly to the environment, and are just constantly growing, spreading their home.

Segment 3: Digging Deeper Logistical and Exponential Growth

Logistic and exponential growth fall into Population ecology, the study of how populations — of plants, animals, and other organisms — change over time and space and interact with their environment. Populations are groups of organisms of the same species living in the same area at the same time. And are examples of population growth: how the size of the population is changing over time.
Studying how and why populations grow or shrink, help scientists make better predictions about future changes in population sizes and growth rates. This is essential for answering questions in areas such as biodiversity conservation and human population growth. Also population growth gives scientists insight into how organisms interact with each other and with their environments. This is especially meaningful when considering the potential impacts of climate change and other changes in environmental factors (how will populations respond to changing temperatures? To drought? Will one population prosper after another declines?).

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

The Population Growth Equation

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #26

Welcome to My AP Biology Thoughts podcast, my name is CJ and I am your host for episode 26 called Unit 8 Ecology, The Population Growth Equation. Today we will be discussing The Population Growth Equation.

Segment 1: Introduction to Human Impact in Ecology

Let's start us off with a little bit of background knowledge. The population growth equation was founded in the late 18th century by a couple of biologists. The big one was Thomas Malthus. He saw that populations grew in a geometric pattern. He came up with two models. It is important that we distinguish these two models. One is for logistical growth and the other is for exponential growth. Just like in math, exponential growth is just a line on a graph that looks like a “J”. In fact, in biology, they are often called Exponential growth curves “J” curves. Now logistical growth is similar, up until a crucial point of the population. The curve seems to hit an impasse, or a number on the ‘Y'' axis that will never see a point. Instead of the line continuing up like in an exponential graph, it levels out and shoots to the right, as if hitting a limit. Now this limit is not just a number on an axis. This number represents the carrying capacity of an ecosystem. This carrying capacity is the maximum amount of species in a singular environment. This is most likely due to limiting factors, whether it be biotic or abiotic. Now limiting factors are things in an ecosystem that prevent a species from growing in population without a limit. Now biotic limiting factors are living things, such as lack of food or abundance of predation. These all can limit the total population of a species. Abiotic limiting factors are nonliving things, such as a storm or lack of water or pollution. All of which could kill off a population or make them compete for vital resources.

Segment 2: Example of Human Impact in Ecology

A huge example of exponential growth rates, are any invasive species. Invasive species in the dictionary are defined as having exponential growth in their population. No predators and unlimited resources. Where they go their population is destined to boom and show no signs of slowing. Invasive species we know and hold near and dear to our hearts are stink bugs, the Asian Giant Hornet, Asian Carps, Japanese Beetles, and of course, the Spotted Lantern Flies. All of these came over and had no predators, so naturally, they breed and reproduce unlimitedly. This is a huge problem because their large numbers knock out any other species with the same niche.

Segment 3: Digging Deeper Human Impact in Ecology

Enough about the qualitative information about Population Growth Curves, and to the quantitative. Exponential growth curves have an equation of dN/dT = rN. Now, dN/dT stands for the rate at which the population grows. R stands for the maximum growth rate per capita. N stands for the population size. There are other ways to find dN/dT however. The easiest is to subtract the total number of births in a year, with the total number of deaths. For the logistical curves, the equation is similar, except for the equation K minus N over K being multiplied in there. K stands for the carrying capacity. This tiny equation basically stands for the maximum amount of a species in an ecosystem. This can be vital when trying to investigate ecosystems and seeing what limiting factors have the greatest impact. Seeing the carrying capacity can help us realize where a species is capped off at and where its population cannot supersede.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Endotherms and Ectotherms

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #25

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode #25 called Unit 8 Ecology: endotherms and ectotherms. Today we will be discussing the difference between endotherms and ectotherms.

Segment 1: Introduction to endotherms and ectotherms

Endotherms are organisms that use internally generated heat to maintain body temperature. They typically keep a steady body temperature regardless of their environment due a process called homeostasis. Homeostasis, which are mechanisms like shivering and sweating, keeps an endotherm's internal temperature steady. On the other hand, Ectotherms are organisms that mainly depend on external heat sources in order to regulate their body temperature. Their body temperature fluctuates based on their surrounding environment’s temperature. Their regulation methods include seeking sun when they need heat and shade when they need to cool down. Unlike endotherms, they are able to survive off of a range of body temperatures instead of needing to maintain a set temperature. Since ectotherms use outside sources for heat, they are able to eat much less food than endotherms. Ectotherms have a much lower metabolic rate than endotherms because they use a lot less internal energy to regulate their body temperature. About 50% of ectotherms food energy is used for growth and reproduction, while endotherms use most of their food energy during metabolism to maintain their body temperature. This is why endotherms require 5 to 20 times more food than an ectotherm of the same size.

Segment 2: Example of Endotherms and Ectotherms

Weather with a t-shirt on, just like every endotherm, you would start shivering. That is unless you are some kind of superhero. On the other hand, if heat generation exceeds heat loss, regulating mechanisms will increase heat loss. So if you were in Florida during August with a winter coat on you would start perspiring, or if you were a very hot dog you would start panting. Now onto Ectotherms, these are the organisms known as “cold-blooded animals”. Ectotherms include most fish, amphibians, reptiles, and invertebrates. When an ectotherm needs to increase its body temperature, it will seek out heat sources. For example, an alligator will bath in the sun, or a lizard will sit on hot pavement. On the other hand, when ectotherms need to cool off, they will seek out shade. For example, a lizard might go hang out under a shaded rock. However, some ectotherms regulate their body temperature by living in environments that have fairly constant conditions. These include a lot of marine invertebrates, who live in aquatic conditions that fluctuate very little, so they don’t have to seek out heat or cooling sources. Their body temperature matches that of the surrounding water.

Segment 3: Digging Deeper Endotherms and Ectotherms.

So after learning all of this about ectotherms and endotherms, you might be wondering why organisms need to regulate their body temperature? Well the simple answer is that they would die if they didn’t. When cells are as cold as water’s freezing point crystals will form inside of them, which will most likely cause the cells membrane to rupture. On the other side, when the body gets too hot (above 104 degrees Fahrenheit) enzymes and proteins in cells will most likely start to lose shape and function, aka denature. As khan academy explains “The rate of chemical reactions changes with temperature, both because temperature affects the rate of collisions between molecules and because the enzymes that control the reactions may be temperature-sensitive.” Reactions are usually faster with higher temperatures up until the denature point. Every species has its own system of metabolic reactions and enzymes that function optimally in a particular temperature range. So by regulating body temperature to a certain range, organisms are able to keep their metabolic reactions running smoothly. Without body temperature regulation organisms would not be able to survive.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Autotrophs, Heterotrophs, and Chemotrophs

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #24

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 24 called Unit 8 Ecology: Autotrophs, Heterotrophs, and Chemotrophs. Today we will be discussing the differences between autotrophs, heterotrophs, and chemotrophs.

Segment 1: Defining Autotrophs, Heterotrophs, And Chemotrophs

Autotrophs, heterotrophs, and chemotrophs are organisms who obtain energy in different ways. Autotrophs create their own energy. The word autotroph comes from the root words auto which means self and trough which means food. Most autotrophs use the process of photosynthesis to make their food. This process creates sugars from carbon dioxide and sunlight. Autotrophs are also called producers because they provide oxygen and a food source for animals who are in higher trophic levels. Autotrophs form the base of ecosystems’ energy pyramid since they are eaten by herbivores.
Herbivores are a type of heterotroph. Heterotrophs are organisms that consume other organisms in order to obtain energy because they cannot create their own food. There are multiple kinds of heterotrophs. Herbivores eat plants to obtain energy and are also called primary consumers because they eat the autotrophs, who are the lowest trophic level in a given ecosystem. Carnivores consume meat from other organisms. They are usually predators and can also be secondary and tertiary consumers. Secondary consumers eat herbivores and tertiary consumers eat other carnivores. Carnivores can also be scavengers, which are organisms that eat animals that are already dead.
Chemotrophs can be either autotrophs or heterotrophs. They obtain their energy by the oxidation of electron donors in their environments. This means that they take electrons from available molecules and add oxygen to them to form other molecules for energy. Chemoautotrophs can synthesize their own organic molecules (include auto because they make their own energy). Chemoheterotrophs obtain energy by ingesting preformed carbon molecules since they can’t make their own.

Segment 2: Examples of Autotrophs, Heterotrophs, And Chemotrophs

Some examples of autotrophs are most plants, phytoplankton, and some bacteria. All of these organisms create their own food. The majority of animals are heterotrophs. Deer, rabbits, and some bird species are examples of herbivores because their food source comes only from plants. Lions, snakes, and sharks are examples of carnivores because they get their energy from hunting and consuming other organisms. Bears, dogs, and humans are all omnivores because they eat both plant and animal matter. Scavengers include raccoons and turkey vultures, who usually eat other decaying animals.
Some examples of chemotrophs are some types of bacteria and fungi (but not all bacteria and not all fungi are chemotrophs). These organisms require carbon to survive and reproduce. Because they most often live in hostile environments such as deep sea vents, chemotrophs aren’t as well-known as autotrophs and heterotrophs.

Segment 3: Digging Deeper into Autotrophs, Heterotrophs, And Chemotrophs

These categories fit into the bigger picture of evolution because they show how food webs and trophic levels work together. For example, autotrophs are necessary for heterotrophs to survive. Heterotrophs make up the primary, secondary, and tertiary consumers (higher trophic levels) because they eat autotrophs (lowest trophic level. This shows that all species rely on each other to survive.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Trophic Levels and Energy Flow

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #23

Welcome to My AP Biology Thoughts podcast, my name is Alex and I am your host for episode 23 called Trophic levels and energy flow.. Today we will be discussing these ideas and their importance to ecology.

Segment 1: Introduction to Trophic Levels

Trophic levels are a means to categorize species in an ecosystem by their distance from the energy source. This separates species into different categories, such as producers, primary consumers, and secondary consumers, with some species being able to inhabit multiple categories depending on what they eat.
Energy flow refers to how energy is transferred throughout an ecosystem. Energy generally flows in a linear direction, with energy going from low trophic levels to high trophic levels, with energy being lost to the environment as heat. So, what are examples of these ideas?

Segment 2: Examples of Trophic Levels

A simple example of trophic levels would be an ecosystem of a plant, a worm, and a bird. In this ecosystem, the plant produces energy from the sun, the worm eats the leaves of the plant, and the bird eats the worm. This ecosystem would have the plant be the producer, as it gets its energy from the sun, with the worm being a primary consumer and the bird being a secondary consumer.
Using this same ecosystem, we can also determine how energy flows through the system. The plant produces energy from the sun, and uses a portion of the energy to keep itself alive. This energy is lost to the environment as heat. When a worm eats the leaves, it gets only a portion of the energy that was made by the plant. The same thing happens to the bird: the worm uses some of the energy to live, and

Segment 3: Digging Deeper into Trophic Levels

These topics are extremely useful when explaining the number of organisms in each species. While producers are plentiful due to their ability to be self sufficient, we see that species which take up higher trophic levels exist in relatively small populations. This is due to the fact that only a fraction of energy is transferred between trophic levels, around only 10% per level. This makes food a huge limiting factor for many secondary and tertiary consumers, who have to constantly forage for relatively few calories. Although trophic levels and energy flow are relatively basic ideas, they are essential in understanding many interactions and population numbers of ecosystems.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Food Webs and Food Chains

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #22

Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode 22 called Unit 8 Ecology: Food Web and Food Chains and types of organisms.. Today we will be discussing the classification of different organisms in each trophic level of food webs and varying food chains

Segment 1: Introduction to Food Chains and Food Webs

To start off, let's differentiate between food chains and food webs. The picture shows how food chains are a smaller representation of an ecosystem, so several food chains within one ecosystem make up a food web. Therefore, a food chain will show only one organism at each trophic level, while a food web will show multiple producers for example. That brings us into identifying the types of organisms in these food chains and webs. At the bottom are the producers that convert the solar energy into chemical energy that can be used by other organisms. All producers are autotrophs, meaning they make their own food. These producers are eaten by herbivores known as primary consumers. The next trophic levels are made of secondary consumers, tertiary consumers and so on. These consumers are either omnivores or carnivores. Two other types of organisms that are often forgotten about are detritivores and decomposers. Detritivores consume material to break it down, so this would be like an earthworm. Decomposers feed off of dead decaying matter like fungi. Fungi release a liquid that breaks down the matter to suck up the nutrients. A key element of food chains is that only 10% of energy is transferred between trophic levels, so producers must provide a lot of energy to sustain the highest consumers.

Segment 2: Examples of to Food Chains and Food Webs

A very local example of a food chain here in NJ is shown in the picture including grass as a producer eaten by a grasshopper, who would then be eaten by a small bird. This bird as a secondary consumer would be eaten by a snake as a tertiary consumer. And to take it one step further, an owl could eat the snake. This is an example of only one food chain, so a NJ food web would maybe also include a deer as a primary consumer and a fox as a secondary consumer.

Segment 3: Digging Deeper into Food Chains and Food Webs

Food webs and the role of each organism involved within the food chain fit into the greater picture of ecology because of the effects that changes in energy availability can have on the ecosystem. For example, if there is a decrease in the amount of free energy available to the producer level, it affects everyone. Each trophic level would receive less energy so populations would decrease, and the top trophic levels might even die out. Another example of the effects of energy availability is the germination period of many organisms. A lot of organisms have their babies in the spring when the sun is out for longer periods of time. This is because the producers get more sun energy to grow, which then means that more energy is transferred to the primary consumers to reproduce. To conclude, in the bigger picture of things, the future of food webs is pretty promising. With elevated CO2 levels in the atmosphere from climate change, producers that make their own organic molecules from carbon dioxide will produce more energy. Therefore, more energy is available at the heterotroph levels so populations of consumers would increase. Overall, food webs explain population size and therefore population growth.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Plant Behavior

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #21

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode #21 called “Plant Behavior (phototropism, gravitropism, thigmotropism)”. Today we will be discussing the definitions of all of those concepts as well as a few examples to go along with them. Then, we will connect all of that to the overarching topic of evolution. Hope you enjoy!.

Segment 1: Introduction to Plant Behavior (phototropism, gravitropism, thigmotropism)

We will be discussing the topic of plant behavior which is how plants respond to changes in their environments
Like all organisms, they detect and respond to stimuli in their environments, but they cannot physically move to get away from danger since they are rooted to the soil
Instead, a plants primary means of response is to change how it is growing based on a number of factors
Their responses are normally hormone based because they do not have nervous systems to control them
They can have responses to both internal and external stimuli, however in this episode we will mainly be focusing on their external responses to stimuli
Plant roots always grow downwards because they have specialized cells that respond to gravity which is an example of a tropism
A tropism is turning towards or away from a stimulus in the environment
The first type of tropism is called phototropism which means the plant is growing towards a light source
This response is controlled by a plant growth hormone called auxin
Auxin stimulates cells on the dark side of a plant to grow longer which provokes the plant to bend towards the light
The next type of tropism is called gravitropism, or geotropism where “geo” means the Earth and tropism refers to turning
Gravitropism is the growth of a plant’s organ or change in the direction of its growth in response to gravity
Since plant cells are able to sense gravity, if a root is not growing towards the center of the earth, the cells become aware of that and change it
Auxin is also stimulated either at the root caps or the shoots to allow cell elongation
Finally, there is also thigmotropism which is the response to touch
The stimulating factor is generally a hard surface that can change the direction of the plant’s growth or the growth of one of its organs
Thigmotropism can be in the form of opening or closing of parts of the plant such as the petals or leaves, the coiling of the plant around the surface, as well as other ways

Segment 2: Examples of Plant Behavior

The first example is a picture of a plant shoot exhibiting the response of phototropism
It is growing toward the light source which is the sun in this case, and its cells are being elongated due to the auxin being released on the dark side of the shoot
There are two types: positive phototropism is growth towards a light source; negative phototropism is growth away from light
Shoots generally display positive phototropism which is being demonstrated in this example since it is bending towards the light which helps the green parts of the plant get closer to a source of light energy, which can then be used for photosynthesis

This picture is demonstrating gravitropism in both a positive and negative way because the roots are growing down, and the shoots are growing up
Positive gravitropism occurs when roots grow into soil because they grow in the direction of gravity
Amyloplasts, which are found in the root caps of plants, settle downward in response to gravity
Negative gravitropism occurs when shoots grow up toward sunlight in the opposite direction of gravity

The most common example of thigmotropism can be seen in the behaviors of a plant called a tendril
Tendrils are common on twining plants such as the morning glory, and prior to touching an object, tendrils often grow in a spiral like form
However, when the tendril touches an object, epidermal cells control the growth of the tendril which can result in the tendril completely circling the object within five to ten minutes
Thigmotropism by tendrils allows plants to “climb” objects and thereby increases their chances of intercepting light for photosynthesis.

Segment 3: Digging Deeper into Plant Behavior

How does this topic fit into the greater picture of ecology?

Overall, ecology is the branch of biology that deals with the relations of organisms to one another and to their physical surroundings
The behaviors exhibited by plants display their relation to the environment and how they need to respond to their surroundings in order to survive
Their physical surroundings are known as stimuli because they insinuate a response from the plants through their upward and downward growth

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Animal Behaviors Part 2

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #20

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode 20 called Unit 8 Ecology: Animal Behaviors Part 2: Instincts, Fixed-Action Patterns, Imprinting, and Associative Learning. Today we will be discussing some of the different animal behaviors, what causes these behaviors, and how this connects to ecology.

Segment #1: Introduction to Instincts, Fixed-Action Patterns, Imprinting, and Associative Learning

Animal behavior includes all the ways animals interact with other members of their species, with organisms of other species, and with their environment. These behaviors are prompted by both internal and external stimuli. Animal behaviours can be both innate and learned. Innate behaviors are genetically hardwired and learned behaviours are learnt through the individual animals experience. All animals are said to have innate behavior apart from humans. Humans have instincts, like the instinct to eat, but this can be influenced by human consciousness and the environment. An instinct is the ability of an animal to perform a behavior the first time it is exposed to the proper stimulus. This is an animal's first reaction and since it doesn't have to be learned, it is an innate behavior.

Segment #2: Examples of Instincts, Fixed-Action Patterns, Imprinting, and Associative Learning

naturalist, found that when young birds came out of their eggs they would become attached to the first moving object they encountered. In most cases in the wild, that would be their mother. But Lorenz replaced himself as the object of their affection. They would also attach to inanimate objects like a white ball and an electric train – if it was presented at the right time. Associative learning is where animals learn something based on a stimulus. A new response becomes associated with a particular stimulus and this applies to almost all learning done by animals with the exception of habituation. This type of behavior is learned over time. An example of this is Pavlov’s dogs. Pavlov started his experiment from the idea that dogs don’t learn to salivate whenever they see food. This reflex is an instinct .In his experiment, Pavlov used a metronome as his neutral stimulus. By itself the metronome did not elicit a response from the dog's. Next, Pavlov began clicking the metronome before he gave food to his dogs. After a number of trials of this, he presented the metronome on its own. The sound of the clicking metronome on its own now caused an increase in salivation. So the dog had learned an association between the metronome and the food.

Segment #3: Digging Deeper

These behaviors can be connected to the greater topic of ecology. Ecology looks at the responses of organisms to their environments and animal behaviors are animals behaviors to stimuli often caused by their environment. These behaviors can also be connected to the idea of taxis behaviors since many of the behaviors follow a pattern and can be predicted. Certain behaviors can also help an organism survive to reproduce, making them more fit. An example of this is the instinctive behavior of baby birds to open their mouth for food. The birds that are genetically hardwired with the behavior to open their mouth will be more likely to survive and pass this behavior into their offspring.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Animal Behaviors Part 1

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #19

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode #19 called Unit 8 Ecology: Animal Behavior Part 1. Today we will be discussing learned behaviors including associative learning, trial and error, habituation, observational learning, and insight and how it ties into the greater picture of ecology.

Segment 1: Introduction to animal learned behaviors

General introduction

Animal Behaviors: how animals interact with each other and their environment
Learned behaviors: behaviors developed through experience or are taught

Definition of Animal Learned Behaviors

Associative learning: learning to correlate a stimulus with a consequence or effect
Trial and error/operant conditioning: learning to associate a behavior with a reward or punishments
BF Skinner theory: belief that learning and changes in behavior are caused by an individual’s response to stimuli. The response either leads to a consequence or reward and over time, it reinforces/alters how an organism responds.
Habituation: decrease in response to a repeated stimulus that causes little effects/impact, enables animals to disregard unimportant stimuli
Insight: uses reason and past experiences to solve problems and form conclusions

Segment 2: Example of animal learned behaviors

Associative: Pavlov’s dogs, giving dogs steak and ringing the bell leads the dog to start salivating over time when the bell is rung because it associates it with steak
Trial and error/operant conditioning: in the Skinner box, a mouse learns to press the level because the pressing level behavior leads to a reward (food pellet)
Habituation: over time baby birds will stop fearing leaves falling since they learn that it poses no harm
Observational learning: baby wolves wolves observe and copy the behavior of adult wolves when they hunt which teaches them predatory skills and effective hunting behaviors such as hunting in packs and surrounding its prey
Insight: Jane Goodall observed that chimpanzees use twigs as a tool to “fish” for food
They would use the twig and poke a hole into a termite mound and eat the insects clinging to it.
Over time, they have been seen making several different types of tools such as sharpening sticks for hunting and stones as hammers to crack open nuts.

Segment 3: Digging Deeper into animal learned behaviors

How does this topic fit into the greater picture of ecology?

Ecology: how organisms interact with one another and with their physical environment
Behaviors are learned through external stimulus from the environment
Seen in associative learning, trial and error, habituation, and insight
Abiotic factors such as food and water lead organisms to gain learned behaviors
Behaviors are learned through organism interactions with another
Seen in observational learning
Changes in behavior due to physical environment: when the environment changes, learned behaviors will change in order to adapt
Behaviors that increase fitness will allow individuals with that behavior to have a greater chance of passing it on to their offspring. Over time, the behavior will dominate in the species since organisms learn that it is beneficial to their survival

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Innate, Learned and Complex Behaviors

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #18

Welcome to My AP Biology Thoughts podcast, my name is Jacky and I am your host for episode 18 called Unit 8 Ecology: Innate, Learned, and Complex Behaviors. Today we will be discussing the different behaviors animals engage in in response to stimuli.

Segment 1: Introduction to Innate, Learned, and Complex Behaviors

Animal behavior is how animals interact with one another and to the environment. The behaviors are specifically triggered by stimuli, which can be internal or external.
EX internal: Need to maintain homeostasis. If an animal eats some bad food, they’re body will often react in a manner to try to throw up that food
EX external: Changes in weather will often lead to migration, where an animal leaves their habitat to go to a whole new region
Three main types of behaviors: Innate, Learned, and Complex
Innate and Learned are two distinctive categories of behaviors, Complex is a mixture of both

Segment 2: Example of Innate, Learned, and Complex Behaviors

Innate behaviors are behaviors animals are genetically programmed to engage in. They are instinctive, and are automatically performed by an animal in response to a stimulus.
Three types: Reflexes, taxis and kinesis. For these 3, I will be using an example of shining light.
Reflexes: A natural response to a stimulus. It was with you the day you were born; an automated reaction by your body. When you go to the doctor, they shine light in your eye. Automatic reaction, or reflex, is to blink or squint; you don’t even think about it.
Taxis: Movement away from or toward a stimulus. It is not random; it is a purposeful response of the animal. If you shine a light in the air at night, you will notice bugs gravitate towards it. This is a natural behavior of theirs; they are attracted to sources of light and will move to it, especially during night time.
Kinesis: Random movement. There is no defined purpose in the behavior, it is simply stray movement that occurs when a stimulus is introduced. The animal is not moving toward or away from anything. If you are in a dark cave and then shine a light on a cluster of rats, they will scatter and move around erratically, not going anywhere in particular. They are not trying to move toward or away from the light, they are just trying to move.
Learned behavior: Behavior that is acquired through experience. It is not a reaction one will have from birth. Some common examples of learned behavior are habituation, classical conditioning, and operant conditioning, observational learning, and insight learning. Will be using example of fire alarm
Habituation: When the natural response to a stimulus decreases overtime as the animal is repeatedly subjected to the stimulus, causing them to become almost unreactive to it. You live in a building with a fire drill once a month. When you first moved in, you were shocked when it went off, but now you stay calm and hardly react. You have been habituated to the stimulus
Classical conditioning: When an unrelated stimulus becomes associated with another stimulus that naturally produces a specific response. Humans are afraid of fire. The stimulus is the fire, and the response is the fear. The sound of the alarm should be unrelated to our fear, but we have been classically conditioned to associate the fire alarm with the stimulus of fire, causing us to become fearful when we hear it.
Operant conditioning: Learned behavior that is more or less likely to happen again based off of the consequences of a certain action. If the consequence of the action is desirable, the action is more likely to be repeated. If the consequence is not desirable, it is less likely to be repeated in the future. Let's say you are an inexperienced chef who is not very attentive when making food. Unfortunately, one day your turducken burns due to your lack of supervision, causing the fire alarm to go off. You hate the alarm and are extremely scared by it, and in the future you are encouraged to keep a more watchful eye on your food due to the negative consequences if you don't.
Observational Learning and Insight Learning are simpler and quite self-explanatory.
Observational: Learning that occurs by watching someone or something else perform an action, which you then mimic.
Insight: An aha moment where you use reasoning to come to a conclusion or solution, allowing you to solve a problem or move forward in a situation and giving you more learning experience.
Complex behaviors: Combination of different types of behaviors: innate or learned. It often requires many actions and decisions in order or at the same time, making it more complex than a singular action. Some common examples are fixed action patterns, migration, and even running, swimming, or flying. I’ll be using the example of birds.
Fixed action patterns: A complex behavior that is already hardwired in an animal but requires much precision or effort to carry out. One example of this would be a bird performing mating dance. Mating dances are often highly complicated, but they are innately ingrained in the bird; the bird simply must carry them out to attract a mate.
Migration: Seasonal movement of animals from one region to another. Again it is an innate response an animal will have from birth combined with learned behaviors that enable them to physically travel (flying, running, etc). Certain birds will naturally migrate to warmer areas when it becomes cold, which is a multi-step, often tedious process that requires constant, complex, action.
I mentioned even supposedly simply behaviors like running, swimming, or fling are complex behaviors. These behaviors combine learned behaviors (the physical movement) with reflexive responses that help with balance or movement. So they are complex behaviors as they still combine learned and innate behaviors, but in a more subtle manner.

Segment 3: Digging Deeper Innate, Learned, and Complex Behaviors

The development of behaviors, whether they are innate, learned, or complex, are the basis of an animal’s life and actions. What they do will have a great impact on their fitness and survivability in their environment and the various stimuli provided by it. Certain innate behaviors, if performed better than others, will make an organism better suited for survival or for finding a mate. The same goes for learned and complex behaviors, which can make or break the fitness of an organism. Eventually, because the organisms who perform these behaviors tend to live longer and produce more offspring, more of their genes will be passed down future generations, who are likely to imitate their parents. Therefore, animals with the ability to better perform certain behaviors, innate or learned, will become more abundant. This shift in individuals signifies a change in the frequencies of alleles in the gene pool over time, which may lead to evolution. Overall, animal behavior, whether it is innate, learned, or complex, is essential to the life and survival of an organism.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Internal and External Stimuli

Hopewell Valley Central High School — Mon, 15 Feb 2021 09:00:00 -0500

My AP Biology Thoughts

Unit 8 Episode #17

Welcome to My AP Biology Thoughts podcast, my name is Arthur and I am your host for episode 17 called Internal and External Stimuli. Today we will be discussing the different kinds of stresses induced upon organisms that evoke different responses.

Segment 1: Introduction to Internal and External Stimuli

Important Definitions:

Internal stimulus:
A stress that comes from within the organism to provoke a response.
External stimulus:
A stress from the outside environment induced upon an organism.
Homeostasis:
The state of stability where all essential biological functions can optimally be carried out.

Segment 2: Example of Internal and External Stimuli

Internal Stimuli:

Hunger:
Obtain glucose to carry out cellular respiration.
Thirst
Obtain water to allow for breathing and the transportation of oxygen throughout the body.

External Stimuli:

Temperature:
Endotherms need to maintain their core body temperature so if the outside environment is too hot or too cold, the organism will respond in a way to maintain the core temperature.
Ectotherms need certain temperatures in order to maintain their metabolism, so they will either move to warmer or colder locations.
Sunlight:
Plants when hit with sunlight will experience phototropism in order to allow them to get the maximum amount possible.

Segment 3: Digging Deeper Internal and External Stimuli

The existence of food webs and chains is dependent on organisms consuming one another. In order for this to happen, the consumers need the stimulus of hunger.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts and digital content, make sure that you visit www.hvspn.com. See you next time!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Convergent and Divergent Evolution

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #14

Welcome to My AP Biology Thoughts podcast, my name is Corrinna and I am your host for episode 14 called Unit 7 Evolution: Convergent and Divergent Evolution. Today we will be discussing the differences between convergent and divergent evolution.

Segment 1: Introduction to Convergent and Divergent Evolution

Convergent and divergent evolution are different types of evolution, and there are many examples of each.
Convergent evolution is when two unrelated species evolve to have analogous structures due to similar natural pressures in their respective environments. Analogous structures are structures that have similar functions in unrelated organisms. Because convergent evolution takes place due to similar pressures in different environments, it makes sense that it produces analogous structures since these structures have similar functions.
Speciation is when distinct species evolve during the course of evolution. Divergent evolution is a type of speciation. Divergent evolution is when different species evolve from a common ancestor, which is a result of the original group developing differences in reaction to different pressures in their environments. Divergent evolution produces homologous structures, which are structures in different organisms that serve different purposes but have similar structures, which suggest a common ancestor.

Segment 2: Examples of Convergent and Divergent Evolution

There are many examples of both convergent and divergent evolution. One example of convergent evolution is the evolution of wings in both birds and bats. Although birds and bats did not originate from the same common ancestor, the structure of both wings are supported by a modified five-fingered limb. Birds and bats show convergent evolution because their similar structures were developed as a result of similar environmental pressures rather than a common ancestor. Another example of convergent evolution are placental mammals and marsupials. Placental mammals, which live in Europe, Africa, and America, undergo gestation in their mother’s uterus and are born fairly advanced, while marsupials are born immature but develop in their mother’s pouches. Marsupials live in Australia. Because each group developed similar analogous structures because of similar habitats and feeding patterns, placental mammals and marsupials show convergent evolution. It is clear that these groups didn’t have a common ancestor because they give birth in different ways, but environmental pressures allowed them to develop similar structures.
One example of divergent evolution is the different kind of finches that Darwin discovered on the Galapagos islands. Finches on different islands had developed different beak structures due to different food sources. For example, Finches that ate insects had longer and thinner beaks than finches who ate seeds, who had short and thick beaks. These finches all evolved from the same common ancestor, but developed specific beak structures due to different environmental pressures. The finches eventually evolved enough that they became different species. Another example of divergent evolution is the evolution of primates. All primates evolved from a single ancestor which lived around 65 million years ago, when the continents were mostly connected. As the continents split and primates moved to different environments, they evolved to develop traits that would be beneficial in those environments.

Segment 3: Connections to Evolution

Convergent and divergent evolution both prove evolution and natural selection. Convergent evolution shows that similar environments can produce similar structures, which shows that these structures were the most fit in those specific environments. Divergent evolution shows natural selection because it proves that species can adapt to their environments. Since speciation occurs with divergent evolution, it shows that different traits become more beneficial and survive in different environments, eventually becoming separate species.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Allopatric vs. Sympatric Speciation

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #9

Welcome to My AP Biology Thoughts podcast, my name is Adrienne and I am your host for episode 9 called Unit 7 Evolution: Allopatric vs. Sympatric Speciation. Today we will be discussing the differences between allopatric and sympatric speciation and I will provide examples for each.

Segment 1: Introduction to Allopatric & Sympatric Speciation

Speciation: formation of a new species, occurs when a group of organisms isn’t capable of interbreeding and producing viable offspring anymore
Allopatric speciation: occurs through geographical isolation like a physical geographic barrier
Sympatric speciation: occurs without a geographical barrier
Driven by other factors: habitat differentiation and sexual selection.

Segment 2: Example of Allopatric & Sympatric Speciation

Allopatric speciation

Ex. Isthmus of Panama: narrow strip of land that causes a geographical barrier between Caribbean sea and Pacific ocean
Two species of porkfish have emerged

Sympatric speciation: 2 types (prezygotic and postzygotic barriers)

Prezygotic barriers: before the sperm and egg
Habitat: different times of year organisms reproduce
Ex. 2 related frog species, Rona aurora breeds earlier in the year than Roma poyilil making them unavailable for each other
Behavioral: set of certain behaviors that must be executed to reproduce
Ex. New Birds of Paradise and Birds of Paradise have different courtship characteristics
Mechanical: the sexual parts must fit like a “lock” and “key”
Ex. 20 different species of Bush Babies, different sexual parts won’t fit and allow reproduction
Gametic isolation: if the gametes are incompatible, the organisms won’t reproduce
Ex. Cells of red and purple sea urchins are genetically incompatible, fertilization is impossible
Postzygotic barrier: after sperm and egg
Inviability: organism dies before reproduction
Infertility: organisms can’t form gametes
Breakdown: F2 generation doesn’t sexually develop properly
Ex. Horses and donkeys produce a mule but it cannot reproduce due to hybridization problems

Segment 3: Digging Deeper Allopatric & Sympatric Speciation

Connect to evolution: speciation is a mechanism of evolution, different species emerge because they are not able to mate and reproduce with each other
Ties into evolution because evolution is the change in allelic frequencies over time
Speciation occurs when the gene flow between populations of organisms is stopped
Populations diverge over time
Allopatric speciation: different geographic regions have different selective pressures which leads to changes in the gene pool
Sympatric speciation: factors such as polyploidy and sexual selection leads to different allelic frequencies
Influence certain organisms with certain characteristics and behaviors to mate with each

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Fossil Record and Radiometric Dating

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode # 16

Welcome to My AP Biology Thoughts podcast, my name is Arthur and I am your host for episode 16 called Fossil Record Radioactive Dating. Today we will be discussing the techniques used to precisely determine the age of fossils.

Segment 1: Introduction to Fossil Record Radioactive Dating

A powerful tool that scientists can use to precisely determine the age of samples is radioactive dating.
Exponential decay: The amount of a substance decreases in proportion to its current value.
Half life: A constant amount of time for the amount of the remaining sample to halve.
Carbon 14: A naturally-occurring radioactive isotope of carbon present in small quantities in all organisms. It has a half life of around 5700 years.

Segment 2: Example of Radiometric dating

Since all living organisms are constantly exchanging carbon with the environment, an organism will have around 1 C-14 atom per 1 trillion carbon atoms. Once an organism dies, it stops exchanging carbon with the environment, so the amount of C-14 remaining in the organism will exponentially decay. By observing the amount of C-14 remaining and comparing it to the established baseline amount, we can calculate the age of samples. For example, if we had a tissue sample with an observed C-14 concentration of one per 4 trillion carbon atoms, as that is a quarter of the original amount, we know that two half lives have elapsed, meaning the sample is around 11400 years old. We were able to determine that the preserved “Ice Man” is around 5300 years old via this method. The amount of carbon-14 had to have been 1 atom per 1.9 trillion carbon atoms.

Sources: https://www2.lbl.gov/abc/wallchart/chapters/13/4.html

Segment 3: Digging Deeper with Radiometric dating

How does this topic fit into the greater picture of evolution?
By being able to accurately date ancient samples, we can create temporally accurate phylogenetic trees, allowing us to better understand organisms’ ancestry and evolutionary relationships.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Homologous and Analogous Structures

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #15

Welcome to My AP Biology Thoughts podcast, my name is Alex Jing and I am your host for episode 15 called Homologous Vestigial and Analogous Structures. Today we will be discussing what these different structures are and how they relate to evolutionary biology.

Segment 1: Introduction to Homologous Vestigial and Analogous Structures

So, what are homologous, vestigial, and analogous structures? Each of these terms refers to the structure of something about an organism in a different way.
Homologous structures are organs or skeletal elements that, due to similarity, suggest that they come from a common ancestor. These structures do not necessarily look the same, but are instead just structurally similar.
Analogous structures are similar structures that evolved to serve the same purpose. These structures were not from some common ancestor, but instead were developed in multiple species independently to adapt to a similar environment.
Vestigial structures are remnants of some past feature of the organism that is no longer useful. It usually occurs when a species inhabits a new environment, or is in a new niche, that does not require an old structure.

Segment 2: Example of Homologous Vestigial and Analogous Structures

An example of a Homologous structure are the wings of birds. The wings of birds come from some evolutionary ancestor, but have become diverse due to different birds needing different wings for their environment. Many predatory birds have wings that are specifically good at catching air so they can accelerate fast enough to catch prey. On the other hand, smaller birds that get sustenance off of fruit have wings that work better when flapping, and are used to maintain stability while eating in the air.
An example of an analogous structure are the wings of a penguin and the flippers of a seal. Antarctica is a cold, barren environment, filled with sheets of ice and freezing water. Both the wings of a penguin, and the flippers of a seal were adapted to inhabit this environment. Despite the structure not coming from a recent ancestor, both animals use these limbs to be able to both traverse slippery ice, and swim in freezing water.
An example of a vestigial structure is the leg bone of a whale, where despite being a waterbound creature, it has remnants of a limb that was used for movement on land. This is because whales came from an ancestor that is shared with pigs. This ancestor was a land animal, but since whales only swim, they did not need this leg anymore. Due to lack of use, this limb became a smaller and smaller part of the whale, and eventually came to be this small separated bone in the whale's skeleton.

Segment 3: Digging Deeper Homologous Vestigial and Analogous Structures

Now why are these things important? Well, these structures are extremely useful for understanding the evolutionary history of animals. Homologous structures are useful for studying divergent evolution. Some traits that come from an evolutionary ancestor appear on multiple different organisms, but are changed through adaptations for each individual species. Analogous structures are useful for studying convergent evolution. Species that migrate to a new area need certain adaptations to survive, no matter what species they are. Vestigial structures, similar to homologous structures, are also useful for studying divergent evolution. Vestigial structures can show how a species no longer requires some trait passed down from their ancestors, usually due to a new environment that has no need for this trait.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Adaptive Radiation in Darwin's Finches

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #13

Welcome to My AP Biology Thoughts podcast, my name is Chloe and I am your host for episode 13 called Unit 7 Evolution: Adaptive Radiation in Darwin's Finches. Today we will be discussing the diversification of the mainland species of finches due to adaptive radiation.

Segment 1: Introduction to Adaptive Radiation in Darwin's Finches

It’s important to understand what this all means. Adaptive radiation is a process in which organisms diversify rapidly from an ancestral species into a variety of new forms. A change in environment can introduce a species to new available resources, and can open new environmental niches. These openings cause new competition within the species, eventually leading to a certain trait being more advantageous.
This ties in perfectly with the natural selection mechanism which describes the relationship between overpopulation, variation, competition, fitness, reproduction . The widespread of niches on the Galapagos makes a perfect fit for this mechanism to take place, and for rapid speciation to occur.
This brings us right to the important stuff, the finches. The theory is that a small population of mainland finches migrated to each of these islands with different niches, creating competition for a certain type of resource.
Variation caused one particular trait to be more beneficial than others, causing rapid speciating among these populations

Segment 2: Example of Adaptive Radiation in Darwin's Finches

The finches varied in beak sizes and fur color.
Larger beaks were beneficial in niches where the available food source mostly consisted of large, difficult to open nuts while Smaller and thinner beaks were beneficial where the main source of food was insects because their small beak made it easier to prey on small bugs. This made it easy for competition to take its route, and let the finch that is more fit for the specific food source to survive and reproduce.

Segment 3:Digging Deeper into Adaptive Radiation in Darwin's Finches

To dig in deeper, it’s important to realize how this information is still relevant. This observation that Darwin made gave him evidence for his theory of natural selection that we still use today. The natural selection mechanism that we study still continues to cause organisms to evolve and speciate. Another important concept to this specific example of adaptive radiation is the divergent evolution that occurred, and how each population became a new species due to the available resources. Biogeography also helped Darwin understand the relatedness of the finches on different islands because their closeness in geography helped prove that they were related in some way

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Miller and Urey Experiment

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #12

Welcome to My AP Biology Thoughts podcast, my name is Helena and I am your host for episode 12 called Unit 7 Evolution on Miller and Urey.. Today we will be discussing the first experiment to prove that organic molecules can be formed from inorganic compounds.

Segment 1: Introduction to the Miller Urey experiment

Stanley Miller and Harold Urey were biochemists at the University of Chicago in 1952, who wanted to explore how life came to be billions of years ago. They created an experiment that was meant to simulate the conditions that they believed could have existed on young earth billions of years ago, around the time the first life was thought to have formed. The point of their experiment was to test what kind of environment needed in order to create life. Their experiment tested Primordial Soup Theory developed by both Alexander Oparin and J.B.S. Haldane. The theory states that energy (lighting and rain) energized the gases in earth's early atmosphere to create simple organic compounds that formed an organic “soup”. This soup eventually turned into complex organic polymers and lastly life.

Segment 2: Example of Miller Urey experiment

Miller and Urey tested this theory by designing an experiment in which they used a glass flask attached with a pair of electrodes, to hold water, methane, ammonia, and hydrogen, which were the main components of young earth's atmosphere. This flask was connected to another flask that was half filled with water, and held over a heating source. When the water was heating it vaporized and mixed with the gas mixture. As this was happening electrical sparks were fired between the electrodes to simulate lighting. This simulated atmosphere was cooled so the water condensed in order for it to sink into a U-shaped trap at the bottom of the apparatus. After a day the solution in the trap turned pink, and at the end of the week they removed the boiling flask and added mercuric chloride to prevent microbial contamination. They stopped the reaction by adding barium hydroxide and sulfuric acid. They then evaporated it to remove impurities. They found that 10%-15% of carbon present was in the form of organic compounds. Miller and Urey used paper chromatography and found that 2% of the carbon went into amino acids, including 13 of 22 amino acids essential to make proteins in living cells, glycine being the most abundant.

Segment 3: Digging Deeper into Miller Urey experiment

While the experiment only created organic molecules and not a living biochemical system (which in reality would take thousands of years), the results were still, to a large extent, enough to prove the primordial soup hypothesis. This is significant because the experiment was the first to show that organic molecules can be formed from inorganic compounds. It also inspired various other experiments, building more evidence for this theory of the origin of life.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Genetic Drift Founders and Bottleneck

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #11

Welcome to My AP Biology Thoughts podcast, my name is Pauline and I am your host for episode #11 called Unit 7 Evolution: Genetic Drift Founders and Bottleneck. Today we will be discussing one of the four evolutionary forces called genetic drift and its two examples.

Segment 1: Introduction to Genetic Drift Founders and Bottleneck

There are 4 evolutionary forces that drive changes in a population’s genetics; these include natural selection, sexual selection, genetic drift, and gene flow
The Founders and bottleneck effect fall under the evolutionary force of genetic drift
Genetic drift consists of random non-adaptive changes due to a random event
The Founders effect takes place when members of a population migrate to a new area. The founder's effect is usually a catalyst to adaptive radiation which is an evolutionarily rapid change between populations
The bottleneck effect occurs when a population experiences a catastrophic event (due to natural disaster, overharvesting, or habitat loss) that results in the survival of only a small number of individuals, who represent only a fraction of the genetic diversity that was present in the original population.

Segment 2: Example of Genetic Drift Founders and Bottleneck

Founders effect: This is exemplified by the Eastern Pennsylvania Amish population. Their ancestors migrated from Germany to found their community. The Amish typically marry from within their own community and are isolated, so genetic mutations tend to persist. For this reason, the Ellis-van Creveld syndrome is much more prevalent among their population. The main symptoms of this disorder is short stature and abnormal numbers of fingers and toes.
Bottleneck effect: A common example of this involves the Northern elephant seals. Humans inflicted upon them a population bottleneck through seal hunting. Hunters harvested the Northern elephant seal for its blubber to make oil. The blubber of one adult male elephant seal could produce up to 25 gallons of oil. By the late 1880’s, the seals were considered functionally extinct due to excessive harvesting. The effective breeding population reached a low point of 20-100 individuals. These survivors were moved to Guadalupe island to recover.

https://www.thoughtco.com/what-is-the-founder-effect-4586652

https://www.fisheries.noaa.gov/species/northern-elephant-seal

https://www.researchgate.net/figure/Northern-elephant-seal-population-growth-Estimated-population-sizes-are-represented-by_fig1_320426603

Segment 3: Digging Deeper

How does this topic fit into the greater picture of evolution?

Founders effect: This example ties into the bigger picture of evolution because the increased frequency of this condition in the Amish population is all due to a reduced genetic variation. A small population broke off from a larger population to colonize America. If some of the colonizers are carriers for the disease or homozygous recessive, the prevalence of the recessive allele will be quite dramatic.
Bottleneck effect: As shown by the graph by reasearchgate.net, the seal population has luckily rebounded, but the bottleneck effect significantly reduced their genetic variation. The scientific american blog provides a good explanation on this. They state that the few individuals that survived interbred and passed on their genes to their offspring. In the long run, inbreeding and lack of genetic diversity will often result in higher incidence of harmful mutations due to a disproportionate distribution of alleles.
Overall, both of these effects explain how genetic drift causes big losses of genetic variation for small populations, leading to evolution.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Directional, Disruptive, and Stabilizing Selection

Hopewell Valley Central High School — Wed, 20 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #10

Welcome to My AP Biology Thoughts podcast, my name is Morgan and I am your host for episode # 10 called Unit 7 Evolution: Types of Selection. Today we will be discussing Directional Selection, Disruptive Selection, and Stabilizing Selection.

Segment 1: Introduction to types of selection: directional, disruptive and stabilizing selection

All three are subsets of natural selection (response to environmental changes)
All three cause a change in genetic variance of a population- alleles in the gene pool
Directional selection- SHIFT in gene pool, favors one phenotype
Disruptive selection- INCREASE in variance, selects extreme phenotypes and disregards ‘middle ground’
Stabilizing selection- opposite, DECREASES variation in gene pool, gets rid of extremes and takes average

Segment 2: Example of types of selection

Directional selection is shown through peppered moths (graph of curve moves to the right on spectrum light to dark) single phenotype favored. Result of a drastic environmental change
Disruptive selection- mice on light sand, mice in dark grass, no middle ground (graph moves from one curve to two curves, little to no middle population) drives speciation since two populations separate
Stabilizing selection- population of mice, this time on forest floor which is medium brown, both light and dark will stand out and not be as fit (graph goes from wide curve to narrower with more in the middle and less at sides)
Examples shown on graphs used from the website Bio.LibreTexts.Org

Segment 3: Digging Deeper : connection between types of selection and overall evolution

Overall, all three contribute to changes in populations and shifting of traits. Leads to speciation, especially disruptive. Under the umbrella of natural selection.
Def. of evolution- process of organisms changing, developing and diversifying over time.
Relates to central dogma since mutations in the gene sequences are what causes any changes in phenotypes. Difference in the DNA leads to a difference in the code sent to the RNA and therefore a difference in the protein it makes

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)
Licensed under Creative Commons: By Attribution 4.0 License
http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube
Connect with us on Social Media
Twitter @thehvspn

Evolutionary Relationships: Phylogenetic Trees and Cladograms

Hopewell Valley Central High School — Fri, 15 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Welcome to My AP Biology Thoughts podcast, my name is Charles but you can call me Darwin and I am your host for today. This is podcast number 8 called Evolutionary Relationships. Today we will be discussing Phylogenetic trees and Cladograms.

Segment 1: Introduction to Evolutionary Relationships

Phylogenetic Tree-

A diagram that shows evolutionary relationships among species
Uses DNA sequences to find patterns in species
There is a distinct difference between cladograms and phylogenetic trees. Cladograms are shaped like a “y” but with a lot more lines branching off. This diagram is based on hypothesis and does not use DNA sequencing. It’s mainly based on homologous structures and noted similarities between animales. Each protruding line from the base represents a time where a structure split off, such as a heart having 4 chambers or having webbed feet.
Phylogenetic trees are mainly used to show time. It is shaped like a very geometric tree sideways. The trunk is the common ancestor for all of the species at the tip of the branches. Each junction represents a closer common ancestor. If a line stops short, that usually means the species went extinct.

Cladograms-

DNA sequencing is a process of finding common ancestors. Since All cells have DNA, which contain a series of different letters that describe that organism. If some of the sequences in DNA matches that of another species, that could mean they are related or share a common ancestor.
are different ways to find the common ancestor of a species, one way is to find homologous bones structures in creatures, which could relate species. However, the most definitive way to find common ancestors, is to look at similarities in DNA sequences.

Segment 2: Example of Phylogenetic Trees and Cladograms

There are tons of examples, and you can search up a diagram for any animal. Looking at a human Phylogenetic tree, we can see that humans are more closely related to chimpanzees than any other monkey. Also, Humans are more closely related to cats, than cows. In addition to looking at phylogenetic trees, you could look at similarities in DNA sequences. Cats are 85% similar to humans, while cows are about 80% similar. It doesn’t seem like cats should be my brothers, however that remaining 15% has critical DNA letters that change various aspects of a creature. If we were to look at a cladogram, we would see the line for humans would be separate from cats, and the segment in between would represent a time where fur stops being useful or hind legs are being primarily used.

Segment 3: Digging Deeper and Making Connections

How does this topic fit into the greater picture of evolution?

Cladograms and Phylogenetic trees come hand in hand when determining common ancestors. These common ancestors are the key to seeing how the species was able to evolve and split off into different organisms. While cladograms help us determine specific structures and when organisms split off, they are not scientific. Meaning they're based off of hypothesis, or what we think it would look like. Phylogenetic trees are more scientific, meaning it helps show specifically who is the most recent common ancestor and who closely related organisms are to each other. It is quinicential in finding the common ancestor in order to see the steps a species took to evolve. We can also see the environmental pressures that a species endured and look at how it affected the present species.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Evidence of Evolution

Hopewell Valley Central High School — Fri, 15 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode 7

Welcome to My AP Biology Thoughts podcast, my name is Victoria and I am your host for episode #7 called Unit 7 Evolution: Evidence of Evolution. Today we will be defining the 4 Pieces of Evidence for Evolution, giving examples of each, and making connections to the unit of evolution.

Segment 1: Introduction to Evidence of Evolution

What is evolution?

A change in the allelic frequencies of a gene pool
Continuous

4 Pieces of Evidence of Evolution -

Fossil Record
the preserved remains of traces of any organisms from the remote past, included both discovered and undiscovered
Only the hard parts of an organism are preserved
Fossil evidence can be either
Direct (body fossils): bones, teeth shells, leaves
Indirect (trace fossils): footprints, tooth marks, tracks, burrows
Like timeline, different kinds of organisms do not occur randomly but are found in rocks in a consistent order, this is known as the law of fossil succession
It is incomplete, and requires an unusual combination of specific circumstances for it to occur, creating many gaps in the fossil record
Biogeography:
Organisms located in one area of the planet are closely related than those found in other parts of the planet
It describes the distribution of organisms, over geographical areas, both in the past and present
Comparative Anatomy:
The comparison of the anatomic features of different species
2 Key types of structures that support this
Homologous structures
Demonstrate a similar underlying anatomy due to shared evolutionary origin, but have evolved into a variety of distinct forms or speciation due to the presence of different selective pressures
The more similar the homologous structures between the two species are, the more closely related they are likely to be
Adaptive radiation through divergent evolution, as similar basic organisms have been adapted to suit various environmental niches
Analogous structures
Adaptations that have similar features and functions as a result of exposure to a common selective pressure, but have different underlying anatomies due to having unrelated evolutionary origins
Shows convergent evolution as unrelated species have become structurally more alike due to exposure to shared selection pressures
Vestigial organs
Homologous features that still remain in organisms, but serve no function or purpose in that organism but were once present and functional in their ancestors
Changes in the environment have caused these organs to be useless and as a result over they have lost their functionality, they show the evolutionary divergence of a species from a past behavior/activity
Comparative embryology
Studying the growing embryo in animals and plants show that closely related organisms go through similar stages of development
Molecular Evidence:

Identifying conservation in DNA and protein sequences as a basis for determining evolutionary relationships, the comparison of DNA sequences can show how different species are related

Segment 2: Example of Evidence of Evolution

Evolution of the modern day horse (fossil record)

Distribution of marsupials around the earth (biogeography)

Biogeography the distribution of species around the world. It all started with a supercontinent called Pangaea. Over millions of years, Pangaea drifted apart into separate continents in a phenomenon called continental drift. Different species were separated on different continents. In particular, a majority of the marsupial population stayed on the continent known as Australia. Here’s how it went…

The blue line illustrates the distribution of marsupials around the world. The highest concentration today is in Australia. The marsupial species that migrated there was free to breed, causing their populations to proliferate and diverge into new species. However, the marsupials on the rest of the planet could not face the competition and died out, lowering their concentration in those areas.

This is a perfect example of biogeography or distribution of a species around the world. The marsupials were separated by continental drift as pangaea split apart. Now, there is variance in the dispersal of their species around the world, with the greatest amount found in Australia.

Segment 3: Digging Deeper Evidence of Evolution

Fossil Record

It reveals that, over time, changes have occurred in the features of organism living on the planet, aka changing the allele frequencies in the gene pool
It also supports or suggests speciation through evolution, as changes to a common ancestor or ancestral species was responsible for the appearance of a later species
Transitional fossils also reveal intermediary forms that occurred over time taken within a species/genus

Biogeography

Closely related species are usually found in close physical proximity to one another, and that fossils from these regions resemble or share similar features to present organisms
This also supports the idea of a species sharing a common ancestor/lineage

Comparative Anatomy

The presences of homologous structures and shared embryonic development between species shows that they must come from or share a common ancestor
The presences of analogous structures and vestigial organs reveal the role and influence of the environment on the organisms in the process of evolution
For all of these to happen, you need a change in the allelic frequencies for these new or passed down traits to appear

Molecular Evidence

All of these pieces of evidence have something in common… they have prove that there was a change in allele frequencies in the gene pool resulting in a change of traits

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Hardy-Weinberg Theory

Hopewell Valley Central High School — Fri, 15 Jan 2021 09:00:00 -0500

Welcome to My AP Biology Thoughts podcast, my name is Nikki and I am your host for episode #6 called Unit #7 Evolution: Hardy Weinberg Equilibrium.. Today we will be discussing the conditions for a Hardy Weinberg equilibrium, the importance of it, and the equation used to find the characteristics of it

Segment 1: Introduction to Hardy Weinberg

Hardy Weinberg is the use of equations to find out allele and genotype frequencies in a population if Evolution didn’t occur.
This allows us to see what the population should look like without evolution
Dominant vs recessive(p or q)
P and q
q^2 and q^2
p+q+1
p^2+q^2+2pq=1

Segment 2: More About the Hardy Weinberg Theory

So when do we use these equations? Well to use Hardy Weinberg, there can’t be any evolution taking place

Let's remember the 5 fingers of evolution

Genetic drift- little genetic variation, random non-adaptive changes due to random event
Bottleneck or founders
No random events and no migration to new areas
Bison being hunted and now little genetic variation
Non-random mating/ sexual selection
Peacocks with larger and brighter feathers
Mutations
Mutation changing fur color to a totally different color
Gene flow-bring alleles together
Purple bird
Natural selection-non-random adaptive changes
finches

Uncoincidentally the 5 requirements for Hardy Weinberg is

No genetic drift
No sexual selection
No mutations
No gene flow
No natural selection

Segment 3: Connection to the Course

How does this topic fit into the greater picture of evolution?

This topic helps us see a population without evolution

Then, comparing to the actual population with evolution, and there are differences between the hardy weinberg and actual, that shows evidence of evolution as well as how evolution effects

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Population Genetics: Central Dogma, Allele Frequency Equation and Gene Pools

Hopewell Valley Central High School — Fri, 08 Jan 2021 09:00:00 -0500

Welcome to My AP Biology Thoughts podcast, my name is Shriya and I am your host for episode 5 called “Population Genetics: Central Dogma, Allele Frequency Equation and Gene Pools.” Today we will be discussing the definitions of all of those concepts as well as a few examples to go along with them. Then, we will connect all of that to the overarching topic of evolution. Hope you enjoy!

Segment 1: Introduction to Population Genetics: Central Dogma, Allele Frequency Equation and the Gene Pool

Introduce the episode topic

Include definitions and vocabulary

Will be discussing the topic of population genetics which is the study of genetic variation within a population and looking into changes in the frequencies of genes and alleles in populations over time
Natural selection is one of the most influential factors that can affect a population’s genetic composition
Central dogma of biology is when the instructions contained in DNA are converted into a functional product, a phenotype
DNA, contains the genes that determine who you are, and proteins determine the structure and function of all your cells
It describes the two-step process, transcription and translation, of how information in genes flow into proteins, creating a string of amino acids called polypeptides
The DNA has the information which is used by the RNA to make the proteins
The Allele Frequency Equation: an allele is a version of a gene and a heritable unit that controls a particular feature of an organism
The allele frequency refers to how often a particular allele appears in a population
An equation called the Hardy-Weinberg equation is used to calculate the genetic variation in a population: p^2 + 2pq + q^2
p^2 and q^2 are the allele frequencies of the homozygous recessive and homozygous dominant, and 2pq is the allele frequency of the heterozygous genotypes
To get p and q individually, you calculate actual/total # of alleles
With this knowledge, you are able to calculate the total allele frequencies using the equation p + q = 1
The gene pool is calculated using the equation just mentioned, p + q = 1 since it is the sum of both allele frequencies
A gene pool is the collection of different genes within an interbreeding population, and refers to its genetic diversity
The larger the gene pool, the greater genetic diversity, and the better a population is able to withstand environmental challenges

Segment 2: Examples of Population Genetics

Have a natural transition into an example… no need to say “segment 2”

Provide detailed example(s) of your topic

This first example is a depiction of the central dogma and the different processes at work from Khan Academy
DNA directs the construction of the chain of amino acids through transcription, which is when the DNA sequence of a gene is copied to make an RNA molecule
During the second process, translation, mRNA is decoded to specify the amino acids of the polypeptide chain
Overall, information flows from DNA to RNA to a protein, and this directional flow is why it is the central dogma of molecular biology

An example using pea plants demonstrates how to calculate the allele frequency of a population using the total number of alleles and fractions
There are 9 pea plants, meaning 18 total alleles
6 of them are homozygous dominant (WW), 1 is heterozygous (Ww), and 2 are homozygous recessive (ww)
To calculate p and q, set up fractions and convert them into percentages
There are 13 copies of the W allele and 5 copies of the w allele, so the allele frequencies for each are 72% and 28% respectively
If you notice, they add up to 1, or 100%

To show a gene pool, here is a picture of butterflies of 3 different colors: orange, white, brown
You can see the diversity in the population through the different allele combinations: AA (brown), Aa(orange), aa (white)

Segment 3: Digging Deeper into Population Genetics

How does this topic fit into the greater picture of evolution?

The flow of information from DNA to a protein is the process of central dogma which relates to evolution because if a mutation arises out of this process, it creates a change in DNA
This change causes changes in all aspects of that organisms’s life and increases genetic variation, contributing to evolution as a whole
Also, through each protein made you can analyze similarities and differences between organisms to see if they are closely-related and where a divergence might have occurred, leading to evolution
If a gene pool with a mix of alleles stayed the same, there would be very little genetic variation, but changes to the frequencies of alleles demonstrate evolution
Microevolution reflects changes in DNA sequences and allele frequencies within a species over time and these changes may be due to mutations, which can introduce new alleles into a population

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Artificial Selection

Hopewell Valley Central High School — Thu, 07 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #4

Welcome to My AP Biology Thoughts podcast, my name is Sid and I am your host for episode #4 called Unit 7 Evolution: Artificial Selection. Today we will be discussing what artificial selection is, examples of it and how it connects to evolution.

Segment 1: Introduction to Artificial Selection

Artificial selection is when humans use genetic variation in a population of species in order to select which traits they want passed down. Artificial selection occurs when human intervention in a species causes significant change in a gene pool.

Segment 2: Examples of Artificial Selection

Dogs are one of the best examples of artificial selection. Today, when you’re walking down your street you may notice many different kinds of dogs. Some are large, some are small, some have brown fur, some have black fur. But why do all of these dogs look and behave so differently? This is because of artificial selection. Despite their many differences, all dogs are the same species. And as I said before, different dogs will look different, act different and have different sets of advantages and disadvantages. Humans have been using this for thousands of years in order to get these loyal companions for many different purposes. Thousands of years ago, dogs’ ancestors were just wolves. After humans tamed and bred them for thousands of years, they have become what we see today. However, humans didn’t just breed them randomly. They were selective in what traits they considered advantageous and made sure those were the traits that were to be passed down. For example, rottweilers were bred specifically to herd cattle. In order to breed a dog to do such a task, humans purposely breed two dogs with characteristics that would allow them to be efficient herding dogs. By doing this, humans select which traits they want passed down to the next generation of dogs for their own advantage. More examples of this are terriers that are good for catching rodents. In the early stages of what we see as dogs today, the wolves that have become dogs were probably those that were genetically capable of being more comfortable around humans. These wolves likely were able to eat remaining food that humans had left over allowing them to survive and reproduce which caused more wolves that were comfortable around humans. So initially, this was natural selection. After a while humans may have found use for these wolves. Some were able to get rid of pests, some were able to herd, some offered protection. They allowed those wolves to reproduce and after many years we now have dogs as we see them. Today, since a wolf and a dog would be unable to mate, we know that they are now different species entirely.
Examples of artificial selection in different species occur as well. On farms, chickens, cattle, sheep, and pigs are the result of artificial selection and selective breeding. For cows, farmers would selectively breed cows to have cows that serve their purpose the best. They may choose cows that are best suited for meat to reproduce and create more cows that can be turned into meat for human consumption. Farmers also might breed cows that are best suited for milk production together to create more generations of cows that are best for milk production. This is done for a variety of farm animals for a variety of purposes. Still, farmers don’t use artificial selection on just animals. Artificial selection is used to create cabbage, broccoli, cauliflower, brussel sprouts, and kale. Surprisingly all of these vegetables are of the same species. Similarly, bananas are not found as we know them in the wild. In the wild, bananas are small and oval shaped and full of seeds. After humans selected the bananas which were longer and sweeter, they were able to create the sweet and easy to eat bananas we see today. This is another example of artificial selection.

Segment 3: Content Connections

As we know, in the population of every species there is some sort of genetic variation. Because of this genetic variation, species are able to adapt and change throughout time in order to best fit their environment. This occurs in a species' natural environment through natural selection. This however, is much different from artificial selection. Through artificial selection, humans use the genetic variation within a species and evolution occurring naturally by seeing which genes are best suited for their environment, humans choose which genes are most favorable to them. In doing this, change within a species and evolution occurs much faster. This is an example of non random mating (one of the five fingers of evolution) because in order for humans to choose which traits are passed down the mates would be specifically selected for whichever favorable traits they have. After this happens for many generations, the gene pool becomes significantly changed which means evolution has occurred.

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Darwin’s Early influencers

Hopewell Valley Central High School — Thu, 07 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #3

Welcome to My AP Biology Thoughts podcast, my name is Nidhi and I am your host for episode 3 called Unit 7 Evolution: Darwin’s Early Influences. Today we will be discussing what led Darwin to researching and creating his theory of evolution.

Segment 1: Introduction to Darwin’s Early Influencers

Our current belief of evolution is that species change in characteristics over several generations and this can be caused by natural selection. These characteristics are the expressions of genes that are passed on from parent to offspring during reproduction. Natural selection is the process where organisms better adapted to their environment tend to survive and produce more offspring. As a result, the traits that help the organisms survive will be passed down and the gene pool will shift causing evolution.
Darwin’s theory of evolution stemmed from the idea of natural selection. Darwin’s early life can be broken up into 2 parts. The first was his education and influence of his father and the 2nd was his voyage aboard the HMS Beagle.

Segment 2: More About Darwin’s Influencers

One of Darwin’s early influences was his father. His father, Robert Waring Darwin’, had made Medical observations that Darwin would read to learn about human psychology. He was sent by his father to study medicine at Edinburgh University when he was 16. He described this experience as formative. And He believed he received the best science education he could have at a British university. Edinberg was where he was first exposed to the belief that animals share all of humans mental capabilities. This is an early belief that evolved into his research of evolution and the connection between species. He began to research this and was accompanied by his mentor Robert Edmond Grant when he learned about sponges in an effort to unlock the mysteries surrounding the origin of more complex creatures.
Darwin formulated his theory of evolution in private from 1837-1839 after returning from a voyage around the word aboard the HMS Beagle. On his journey aboard, he spent 5 years along the coast of South America exploring the continent and the Galapagos Islands. He filled many notebooks with observations on animals, plants, and geology and collected many specimens he sent home to study. Later in his life, he called the Beagle voyage the most important event in his life, saying it determined his whole career. Before the voyage he was planning a career as a clergyman but when he returned he was well known in London for the specimens had sent home. His beagle voyage is credited for providing him with the seeds for his evolution theory that he would spend the rest of his life working on.
Darwin was also influenced by 3 earlier thinkers. The first is Jean Lamarck who was one of the first scientists to propose that species change over time. However, he was wrong about how species change with his belief that traits an organism develops during its own lifetime can be passed onto offspring. Additionally, Charles Lyell’s book Principles of Geology was taken by Darwin with him on the Beagle. In the book, Lyell claims that the Earth is much older than people believed. Lastly, Thomas Malthus wrote an essay titled On population. In this he argues the population is kept in check by killing off the weakest members when a population gets too large and there aren't enough resources. The ideas of these 3 thinkers greatly influenced Darwin when he was forming his theory of evolution.

Segment 3: Connection to the Course

Darwin’s theory of evolution by natural selection became the foundation of modern evolutionary studies. He is best known for his published book On the Origin of Species. His research of the Galapagos Finches is often cited in class as evidence for evolution by natural selection. He had observed while on his voyage that beak shape varies among finch species. This caused him to theorize that the beak of an ancestral species had adapted over time to equip the finches to acquire different food sources.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Natural Selection Mechanism

Hopewell Valley Central High School — Thu, 07 Jan 2021 09:00:00 -0500

My AP Biology Thoughts

Episode #2

Welcome to My AP Biology Thoughts podcast, my name is Jacqueline and I am your host for Episode 2 called the Natural Selection Mechanism. Today we will be discussing the 5 components of the mechanism, and how they ultimately lead to evolution.

Segment 1: Introduction to Natural Selection

Natural selection, as you probably already know, is the process in which organisms who are better adapted to their environments and have higher fitness pass on their traits to offspring. It is a driving force of evolution, which is the change in the genetic and allele frequencies in a species' gene pool over time. Charles Darwin and Alfred Wallace were the co-discoverers of the theory of Natural selection, although Darwin is most often credited as the sole contributor. Natural selection may be one concept, but it is a broad one, and it can be split into five major components: overpopulation, variation, competition, fitness, and reproduction. These five make up what is known as the natural selection mechanism.

Segment 2: More About Natural Selection

As I explain the natural selection mechanism, I’ll be using the example of Canada geese. Let’s start with overpopulation. Overpopulation is the occurrence where a species’s population increases beyond its habitat’s carrying capacity. It is the rather simple first step of the mechanism, but it sets up a chain reaction of more complicated events. Let’s say the population of Canada geese living in a lake habitat has grown to the point where their aqueous plant food source has become limited and can no longer sustain all of them. Overpopulation has occurred.
One side effect of overpopulation and the second mechanism of natural selection is variation. As more members of a species are born, the genetic and physical variance in that population will increase. This occurs often due to random mutations, which can introduce new traits into populations. It may also happen because of immigration of another population (of that same species) but with different genes into the area, known as gene flow. Basically, more members of a species means more variation of genotypes and phenotypes in the population. A wider array of different traits will be developed among them, some of which may convey advantages or disadvantages for the organism. Now let’s say that the Canada Geese population, which is experiencing an influx in birth rate (AKA overpopulation, the first part of the mechanism), is also more likely to have random mutations, which will lead to increased variation of traits. Short, medium, and long necks are all now traits prevalent in the species.
Another side effect of overpopulation and the third mechanism of natural selection is competition. When there are too many organisms and limited resources, individuals of a species must fight the others around them for those necessities, or risk dying out. However, only the most adept will be able to survive and ultimately reproduce. This ability is known as fitness, and it is the 4th mechanism of natural selection. Being able to outcompete the competition and survive to reproductive age to pass on one’s genes is the prime signifier of greater biological fitness. These individuals often have advantageous genes or traits that give them a leg up against rivals and are more likely to be inherited by future generations. The Canada geese population has breached carrying capacity and now has too small of a plant food source for too large of a group. The geese begin to compete among themselves for the resource. The geese with the trait of longer necks have greater fitness because they are able to reach the plants easier and outcompete those with shorter necks, who die out before reproduction. The surviving long-neck geese reproduce and are officially deemed more fit.
Reproduction is the final component of the mechanism of natural selection, and it ties in perfectly with fitness. The fittest organisms are those with advantageous traits who survive long enough to reach the ultimate goal: reproduction. When this occurs, an organism mates and passes on its DNA to future generations, who will have a higher abundance of the alleles coding for the traits found in more fit individuals (their parents). Let’s say that the long-neck geese, who withstood the environmental pressures better than others, have reproduced. Their offspring will most likely have inherited the genes that are expressed as a long-neck phenotype, which will increase their fitness. Overtime, long-neck geese continue to survive and pass on their beneficial traits to future generations, which could lead to speciation. Natural selection has occurred.

Segment 3: Connection to the Course

So how does the mechanism of Natural Selection factor into the overarching idea of evolution? To put it simply, Natural selection is a driving force of evolution. It is one of the major causes of significant allelic frequency change over time, enough to cause divergence into a new species. More specifically, natural selection means that traits which favor survival are more likely to be passed down through future generations, causing an increase in the frequency of that fitness-increasing allele, or evolution. Each step of the Natural Selection Mechanism factors into this final result; if even one component is removed, evolution may be stunted. The example of the Canada geese represents the mechanism at work in evolution; after the overpopulation, variation, competition, and survival of fittest, the surviving long neck geese will reproduce and have their offspring inherit advantageous traits. The alleles which code for those traits will increase in frequency in the gene pool. Perhaps, overtime, a new species could be formed. Either way, evolution has occurred, and it all started with the mechanism of natural selection.

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!

Music Credits:

"Ice Flow" Kevin MacLeod (incompetech.com)

Licensed under Creative Commons: By Attribution 4.0 License

http://creativecommons.org/licenses/by/4.0/

Subscribe to our Podcast

Apple Podcasts
Spotify
Google Podcasts
Stitcher
YouTube

Connect with us on Social Media

Twitter @thehvspn

Darwin’s Early Life

Hopewell Valley Central High School — Thu, 07 Jan 2021 09:00:00 -0500

Welcome to My AP Biology Thoughts podcast, my name is Saarim and I am your host for episode #1 called Darwin’s Early Life. Today I will be discussing the early life, academia, and internal turmoil of English naturalist Charles Darwin, who is notable for his scientific theory of evolution by natural selection. We all know the name, Charles Darwin, and his idea that all living things developed and adapted overtime as a result of random mutations which gave these organisms traits suitable for their lifestyles. But how did he come up with this idea? The impacts of his theory are enormous as they really show us where all living things come from and the theory even created divisions in society amongst Darwinists/modernists and fundamentalists. But let's go all the way back to explore the origins of this theory.

Segment 1: Introduction to Darwin’s Early Life And Academia

Talking about Darwin in Academia, his experiences in school, transition from medicine to religion, to naturalism and voyage on HMS Beagle, observations from trip/significance, and internal struggle deciding to publish work
Credit New England Complex System Institute and Eric Guise’s AP Biology videos for the following info
Darwin Info
Born in Shrewsbury, England; attended Shrewsbury School
Interested in nature since young age - beetle collection
Father wanted him to be doctor - went to Edinburg Medical School - found lectures boring and couldn’t stand watching surgeries done without pain killers (left med school after 2 years)
Father arranged from him to be priest/clergyman - earned bachelor of arts degree from Cambridge; continued interest in nature
Became friends with two professors at Cambridge - geologist and John Henslow (botanist)
Around the world sailing trip on HMS Beagle being arranged by Royal Navy - John Henslow recommended Darwin as the trips naturalist
Darwin left for a 5 year journey - wrote down all his observations, etc.

Segment 2: Example of Darwin’s Observation During His Journey

Brazil
Visited tropical rainforest: great diversity - began thinking about diversity of life and the creation of different species
Observed animals eating and chasing each other - animals struggled to survive

Argentina
Observed how the grass where the cattle grazed smaller than grass that cattle had been introduced with - idea of something allowing different types of grass to survive

Tierra del Fuego
Saw how well suited native were to their harsh environments

https://www.cake.co/conversations/K2sNdvV/the-last-people-tierra-del-fuego-the-island-of-souls

Chile
Rocks in the south were higher above sea level than the same rocks in north
Earthquake: rocks had been lifted and marine organisms hgh up and dry - changes in environments = changes in organisms
Galapagos
Studied 3 main species: finches, tortoises, and the marine iguanas
Finches
Saw a different type of finch species with different types of beaks on each island depending on the conditions of the specific island - finches with strong beaks that ate large nuts (to open them); finches with beaks designed for just cracking small nuts; finches that ate fruits and insects had different beaks
Darwin developed idea that birds from one species separated to different islands and adapted to new environments

https://en.wikipedia.org/wiki/Darwin%27s_finches

Tortoises
Looked different - different neck sizes depending on the island - must have adapted to get food: long neck (higher vegetation); short neck (lower vegetation)

https://www.mun.ca/biology/scarr/4270_Galapagos_tortoises.html

Marine iguanas
Lizards ability to swim was unique - adapted to survive on scarce food on the islands

https://galapagosconservation.org.uk/wildlife/marine-iguana/

At this point, I will talk about his internal struggle he faced when deciding to publish his observations/theory

Waited 23 years to present his research
Fear over public’s reaction to the theory - very religious - believed that species were fixed and never different (evolution = heresy)
Published his work after encouragement from fellow naturalist, Alfred Wallace
Accepted by some, rejected by some

Segment 3: Digging Deeper Into Darwin’s Impact

https://www.scientificamerican.com/article/darwins-influence-on-modern-thought1/

Darwin founded evolutionary biology - formulated idea of evolution by natural selection
Darwin knew nothing about genetics or DNA structure - no knowledge on the mechanism of heredity (by filling in his possible gaps, we have deeper understanding of evolution)
Four significant contributions to evolutionary biology
Variations arise in species
Branching evolution - common descent of all species from single common ancestor
Evolution is gradual - no major discontinuities
Mechanism of evolution is natural selection
He has answered for us: where do we come from? (biggest breakthrough of life science)

Thank you for listening to this episode of My AP Biology Thoughts. For more student-ran podcasts, make sure that you visit www.hvspn.com. Thanks for listening!