Read more about penguins here.
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American Goldfinches are the only finches that molt twice a year, replacing their golden plumage first in late winter and again in late summer. Each spring, the brightening yellow of male goldfinches is welcomed as an indicator that warmer days are approaching.
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“Much like the ultimate demise of the dodo, the extinction of the thylacine is a frustrating mystery. Our species witnessed the predator’s disappearance – there is even video footage of some of the last thylacines – yet these animals slipped into oblivion before we realized what we were losing. As we learn more about them, they become stranger still, and their loss feels all the more tragic.”
The Amazon rainforest swept news headlines and garnered global attention because of its destructive forest fires in 2019; according to this article (1), the resulting deforestation stripped any protection of natural land, its biodiversity and its indiginous animals. Though the rainforest has slowly been rebuilding, scientists project the fires will have lasting effects for decades, or even centuries. However, ecologist Lucas Paolucci found a surprising contributor to the Amazon ecosystem and an even more surprising method of contributing: feces from tapirs. With the help of dung beetles, this animal might be a key agent for transporting and distributing plants across the Amazon for regrowth.
A team of researchers conducted a study at the Karolinska Institutet in Sweden on a lamprey brain which revealed that the cortex of our brain is over 500 million years old and revealed many new insights on brain evolution. As a starting point a lamprey is a fishlike jawless vertebrae. They live in coastal and fresh waters. According to Britannica, “they have well- developed eyes, one or two dorsal fins, a tail fin, a single nostril on top of the head, and seven gill openings on each side of the body.” It is astonishing to think that a part of the human brain has evolved from a fish.
Over the past few weeks, and likely to continue for the foreseeable future, I have been stuck at home due to the outbreak of COVID-19. Schools are closed until the end of the year, restaurants are only doing take-out, the economy is in a recession, workers are getting laid off, and on top of all that, I can’t even hang out with my friends. The coronavirus outbreak has been an extreme nuisance (to say the least) in my life. So naturally, while browsing youtube (which I do a lot now that I’m trapped in my house) a video entitled “Here’s How YOU Can Help Find a Cure for COVID-19!” caught my eye. In the video, tech Youtuber Linus Sebastian educates his audience on a program created 2 years ago, Folding@Home.
Three useful Terms to know for this Unit
Helicase unwinds the DNA so replication can occur. This is the first step for DNA replication and it is a crucial step because if the two pieces of DNA strands are not separated they can not be copied/ Duplicated. When Helicase unwinds the DNA it creates the Replication fork, that is where you can usually find helicase and is where DNA replication occurs. Helicase unwinds the DNA by breaking the hydrogen bonds that go down the center of the two interlocked strands. Without helicase, DNA replication would come to a halt. Of course we need to replicate DNA so that is why this enzyme is so important for every organism.
Transcription is the most common control point of gene expression for all organisms. It is the first step in gene expression. Transcription is done by enzymes called RNA Polymerases (as you can see in the picture below). RNA polymerases link nucleotides to form an RNA strand from the DNA template strand. Transcription has 3 stages; initiation, elongation, and termination. In initiation the RNA polymerase binds to the promoter (a sequence of DNA) . Then the RNA polymerase separates the DNA strands and they use one of the single strands as the DNA template. Next is Elongation; RNA polymerase reads the template strand and builds the complementary RNA nucleotides that will form a chain from 5’ to 3’. The last stage is Termination, in this stage sequences called terminators signal that the RNA transcript is complete. When they are transcribed they allow the RNA transcript to be released from the RNA polymerase. By the end of transcription you have a function product such as a protein. The purpose of transcription is to create an mRNA copy of a gene so the genetic information can leave the nucleus and be used to assemble a protein.
A nonsense mutation is when the change of a single nucleotide causes a stop codon to be formed. This causes the protein that is being formed with amino acids to stop its complete formation, creating a shortened protein. Often these proteins are completely nonfunctional because they do not have enough coding. Since this mutation often leads to non functional proteins it is more harmful than the average mutation with a single nucleotide. Mutations are more common than I originally thought, most of them go unnoticed because they are silent mutations that have no visible effect although nonsense mutations often have more observable results. All mutations increase with age because we are exposed to more carcinogens the longer we are alive.
Image from Wikimedia Commons
Humans have burned enormous amounts of fossil fuels since the Industrial Revolution, pumping carbon dioxide into the atmosphere. The ocean absorbs vast amounts of heat as a result of increased concentrations of greenhouse gases. The steady absorption of atmospheric heat leads to rising ocean temperatures. Data from the US National Oceanic and Atmospheric Administration shows that the average global sea surface temperature has increased approximately 0.13 degrees Celsius per decade over the past 100 years. Increasing ocean temperatures directly affect marine species and ecosystems. Coral bleaching is one phenomenon mainly caused by these changes to the oceanic equilibrium. Algae called zooxanthellae live in the tissues of corals. The algae undergo photosynthesis to supply essential nutrients to the corals. In return, corals provide algae with a protected environment and the compounds they need for photosynthesis. Reefs are threatened by rising ocean temperatures. Corals will expel the algae that lives in their tissues when the water is too warm. This causes the coral to lose its color along with many of the benefits that come from symbiosis.