AP Biology class blog for discussing current research in Biology

Author: sukrose

Unnatural Selection: The Future of The Future?

Imagine it’s Saturday night, you are snowed in until the morning and you need a way to pass the time. Like many people, you resort to Netflix. Upon browsing through the vast selection of horror, comedy, and romantic films, you decide you are in the mood for a documentary. Scrolling through the options, you stop at a title that grabs your attention: Unnatural Selection.

Since you are an AP Biology student, you immediately connect the words “Natural Selection” to the work of Charles Darwin, the study of genetics, and most importantly: evolution. In brief, natural selection is the survival and reproduction of the fittest, the idea that organisms with traits better suited to living in a specific environment will survive to reproduce offspring with similar traits. Those with unfavorable traits may not be able to reproduce, and therefore those traits are no longer passed down through that species. Natural selection is a mechanism for genetic diversity in evolution, and it is how species adapt to certain environments over many generations.

If genetic diversity enables natural selection, then what enables unnatural selection? Well, If natural selection eradicates unfavorable traits naturally, then unnatural selection essentially eradicates unfavorable traits or promotes favorable traits artificially.

The Netflix docuseries “Unnatural Selection” focuses on the emergence of a new gene-editing technology named CRISPR (an acronym for “Clustered regularly interspaced short palindromic repeats”). CRISPR is a revolutionary new method of DNA editing, which could help cure both patients with genetic diseases and patients who are at risk of inheriting unwanted genetic diseases. The two pioneers of this technology, Emmanuelle Charpentier and Jennifer Doudna, recently won Nobel Prizes in Chemistry for their work on CRISPR.

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Animation of CRISPR using guide RNA to identify where to cut the DNA, and cutting the DNA using the Cas9 enzyme

CRISPR works with the Cas9 enzyme to locate and cut a specific segment of DNA. Scientists first identify the sequence of the human genome, and locates a specific region that needs to be altered. Using that sequence, they design a guide RNA strand that will help the Cas9 enzyme, otherwise known as the “molecular scissors” to locate the specific gene, and then make precision cuts. With the affected region removed, scientists can now insert a correct sequence in its place.

Using the bacterial quirk that is CRISPR, scientists have essentially given anyone with a micropipette and an internet connection the power to manipulate the genetic code of any living thing.

Megan Molteni / WIRED

CRISPR is just the beginning of gene editing, introducing a new field of potential gene editing research and applications. But with great power comes great responsibility — and great controversy. Aside from the obvious concerns, people speculating the safety, research, and trials of this new treatment, CRISPR headlines are dominated by a hefty ethical dilemma. On one hand, treating a patient for sickle cell anemia will rid them of pain and suffering, and allows their offspring to enjoy a normal life as well. However, by eliminating the passing down of this trait, sickle cell anemia is slowly eliminated from the human gene pool. Rather than natural selection choosing the path of human evolution — we are. We are selecting which traits we deem “abnormal” and are removing them scientifically. Although CRISPR treatment is intended to help people enjoy normal lives and have equally as happy children, putting evolution into the hands of those evolving can result in more drastic effects in the future.

For our generation, CRISPR seems like a magical cure for genetic diseases. But for future generations, CRISPR could very well be seen as the source of many problems such as overpopulation, low genetic diversity, and future alterations such as “designer babies.” Humans have reached the point where we are capable of our future. Is CRISPR going to solve all of our problems, or put an end to the diverse human race as we know it? Comment how you feel down in the comments.


Glaciers Hold Less Water than Previously Thought. Is this Good?

Last summer in Alaska, I was kayaking up to the Holgate Glacier when I noticed the water getting colder. I began to feel the katabatic winds as I got even closer to the massive wall of ice. Small ice chunks began to surround the kayak, and I could see the fast moving silt deposits flowing beneath me. I then heard a noise which boomed and echoed off of the surrounding mountains, and I saw a massive chunk of ice break off (“calve”) from the glacier and plummet into the sea. I’ve always known that climate change was happening, but seeing it before my eyes reaffirmed my fears.

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Holgate Glacier, Aialik Bay, Kenai Fjords National Park, Seward, Alaska

I’m not here to talk about my fantastic trip to Alaska, but rather to talk about the new scientific findings which will further predict the climate change battle. Previously, scientists believed that warmer-than-average temperatures can begin to melt glaciers, causing the sea levels to rise and cause disastrous flooding. Just recently, satellite image glacier research spearheaded by Romain Millan of Grenoble Alpes University in France has determined that glaciers hold 20% less water than previously thought. This means that, if all of the glacier ice were to melt, that the seas are predicted to rise 10 inches instead of 13 inches.

This is great news, right? Well, some could argue that less flooding means less disaster (landslides, wipe out infrastructure, etc), and that it’s good news. But it’s not, because even if the sea levels were to rise just a few inches lower, still 29% of the entire world’s population would be predicted to be immediately affected by flooding, and within a few days, 99.9% of the entire world’s population would feel the indirect effects through shortages or outages. In addition, less water quite literally means “less water.” 2 billion people currently rely on glaciers as their primary source of water, so “less water” would effect them through a drought. As

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Glacier at Chugach State Park, Alaska (which I too visited)

we’ve learned in AP Biology, water is one of the most, if not the most, important molecules to biological existence. A drought can affect human life from hundreds of angles, such as famine, or more immediately, dehydration. Water is extremely crucial to performing catabolic reactions such as hydrolysis, which we learned in AP Biology.

Factoring in mountaintop glaciers and their water content, Millan is able to determine the rate at which communities will run out of water. But for the non-alpine communities, these mountaintop glaciers are only a tiny drop in a large bucket. Millan’s research lacks one major component: the antarctic and arctic glaciers. If these unbelievably large ice fields continue to melt at the current pace, 90% of the United States is predicted to be underwater by 2050. To be honest, I believed this statistic was exaggerating until just recently. In Alaska, one of the glaciers named “Exit Glacier” had markers at the glacier’s terminus for each year. As I got closer to the glacier, I noticed the markers getting further and further away, signaling that the glacier was melting quicker and quicker. Take a look at the graph below, specifically how the year intervals begin to get smaller, and let me know how it makes you feel in the comments. Although it does not take a trip to Alaska to realize that climate change is really happening, new and emerging headline-worthy research like Millan’s is truly highlighting the immediate issue we all could face soon.

Exit Glacier Terminus Position From 1950-2020



Changing Course: How Scientists Can Update Vaccines With Emerging Variants

SARS-CoV-2 , the virus which causes COVID-19, is changing rapidly, which in turn warrants changes to the vaccines created to slow its spread. This virus is mutating fast, with a new mutation establishing about every 11 days. These mutations may not be different enough to cause an immediate difference, but each and every person who catches SARS-CoV-2 opens more possibilities for mutations.

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Omicron Mutation Spike Protein

The most recent large variant to be identified was B.1.1.529 Omicron originating in South Africa. The Omicron variant has more than half the amount of mutations as the Delta variant, raising concern among health officials, who fear that the virus may differ just enough from the original for vaccines to be less effective. This fear stems from the idea that the vaccine-created antibodies will no longer be able to recognize the mutated virus’ spike proteins, resulting in an ineffective vaccine.

The current mRNA SARS-CoV-2 vaccines work in a fascinating way. Scientists utilize harmless lab-grown mRNA that contain coded instructions on how to create the SARS-CoV-2 spike protein, and place that technology into a vaccine.

Then, once the mRNA vaccine is injected into the patient, the patient’s cells will create the identical spike proteins, prompting an immune response. As we have learned in AP Bio, the adaptive immune system would eventually churn out antibodies tailored to the spike protein, so any future SARS-CoV-2 virus that enters the body will be neutralized and destroyed, even before it has the chance to infect someone.

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SARS-CoV-2 Vaccine Vial

Because of this technology, scientists are readily able to create an updated version of the SARS-CoV-2 vaccine within a matter of days, for distribution in around three months. How do they “update” the vaccine? First, the Omicron spike protein is sequenced into their nitrogen bases (A, T, G, and C’s). Once that is complete, scientists use this sequence to create a DNA template. They then mix in enzymes which build an mRNA copy of the DNA template through a process known as transcription.

This process unfolds in a matter of days… so why does it take three months? Creating the physical mRNA for the vaccine takes only three days, but then the vaccine makers need to produce enough mRNA for doses, which would be used the next six weeks in pre-clinical testing on human cells. Once pre-clinical testing is complete and proves the vaccine works as expected, then the manufacturing of the vaccine can begin. The vaccine wouldn’t be released just yet — the next five weeks would be clinical trials and testing, and after that, the updated vaccine can begin rolling out to the public.

Even though SARS-CoV-2 is evolving faster than vaccines can keep up with, past technology was no where near as quick as today’s. In my eyes, being able to produce an updated vaccine in a matter of months is nonetheless a scientific feat. Comment what you feel was a gigantic scientific leap during this pandemic below!

Small But Mighty: Sea Otters And Their Leaky Mitochondria

Sea otters: they bob up and down in the water, hold hands when they are sleeping, poop together at social events, stay warm by their fur and leaky mitochondria… wait, what?

Let’s rewind.

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A Cute Sea Otter Floating On Its Back

Warm-blooded marine mammals have a thick layer of fat and oils, known as blubber, as their skin layer to insulate their body. In cold waters, blubber helps retain heat and maintain homeostasis.

But what if warm-blooded marine mammals lack blubber? Sea otters are a prime example (and the only example) of a marine mammal without a layer of blubber. Instead, they have a thick coat of dense hairs, 1000x denser than human hair–the thickest on earth. This enables sea otters to trap large amounts of air within their fur coat, acting as insulation. (This is the same reason why sea otters float: the air trapped in their fur coat makes them buoyant).

But with that said, can you stay warm in a fleece jacket? Possibly. What if you were wearing it while in the ocean? That might be somewhat difficult. Similarly, fur can’t solely protect these animals from losing too much heat. These mammals are still living in water, which transfers heat 23 times as efficiently as air. Since sea otters are the smallest aquatic mammals, they have a lot of surface area relative to their volume, making it even harder for these animals to maintain homeostasis.

So how do they do it? Researchers have already understood that sea otters have an extreme metabolism, how food gets converted to energy in cells, eating about twenty-five percent of their body mass in food every day. But the pieces were still not adding up, which prompted researcher T. Wright to investigate this question on a cellular level. He and his colleagues searched for the source of heat in otters’ muscles. Playing a pivotal role in the body’s metabolism, the skeletal muscle makes up 40 to 50 percent of the sea otters’ entire body mass. His study required the collection of tissue from 21 sea otters of different ages and then measured the muscle cells’ respiratory capacity compared to that of other animals. The sea otters’ oxygen flow rate would roughly indicate the measurement of the cells’ heat production.

Mitochondria pump protons across their cell membranes to store energy in the form of ATP, like we learned in AP Biology’s diffusion unit. From this study, T. Wright concluded that the protons are diffusing back through the membrane before being used for work, resulting in excess heat. Since some of the energy is lost as heat, sea otters need to eat more food to compensate for the lost energy. This “leak in energy” is what contributes to the sea otters’ speedy metabolism.

It’s unknown if sea otters develop leaky mitochondria by living in cold water or simply inherit it. Future research into the fascinating design of sea otters may potentially reveal intriguing insight into their evolution, behavior, and maybe someday, their cuteness.



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