Writing in Biology

Protein is one of those fascinating nutrients that allow extremely good for you there is a maximum healthy limit. There has been numerous studies that have proven this but the exact amount of protein that is in fact to much seems to vary study to study. This specific study goes on to discuss the differences in how the body takes in fast-digesting versus slow-digesting protein. In respect to fast-digesting proteins a young adult can take in 20-25g of protein while still maintaing a lean-tissue building process. This is because the fast-digesting proteins lack the surplus of other macronutrients that could hinder the digestion process. Conversely slow-digesting proteins are more likely to contain other macronutrients that can slow down the digestion process meaning a young adult would be able to consume more because of the delay in amino acid uptake. The study concluded in saying that based on the results a human would most benefit from a 1.6 gram of protein per kilogram of body weight per day diet in order to maximize the lean-muscle building process.

Another example of modern convergent evolution is human adaptation to tropical rainforests. Tropical rainforests are harsh environments for humans. They are marked with high pathogen activity, high temperatures and abundant rainfall, as well as ferocious animals. This type of unforgiving environment likely resulted in human adaptations in response to selective pressures. Researchers studied 660,918 SNP’s looking for outliers in populations living in a tropical rainforest and genetically related populations living outside of the tropical rainforest in Africa, North America and South America. “The most significant positive selection signals were found in genes related to lipid metabolism, the immune system, body development, and RNA Polymerase III transcription initiation. The results are discussed in the light of putative tropical forest selective pressures, namely food scarcity, high prevalence of pathogens, difficulty to move, and inefficient thermoregulation (Carlos Amorim et al., 2015).” Researchers identified seven clusters in five separate chromosomes that show positive selection for potential rain forest adaptations. Two of the clusters only showed evidence of positive selection in North America and South America. Two other clusters only showed evidence of positive selection in Africa. The other three clusters were found in both continents. This is clear evidence of convergent evolution in modern human history.

Stem cell research, specifically embryonic stem cell research, poses a moral dilemma to the respect and value of human life, the topic of debate is whether or not the embryo being used has the status of a human person. Many see the embryo as a person or having the potentiality of becoming a person, but this argument is further deconstructed as to what defines personhood, is it defined through mental capabilities or is it a physical state of being. Those who argue in support of this view, state that the development of a fertilized egg into to baby is a continuous process and that any attempt to pinpoint when and where personhood begins is unnecessary. Once the sperm and egg meet the an embryo must be protected.

The question that I chose was “Why does this graph level off?” This question appears in Lecture 10, on slide 12. It also has a diagram of a graph with [substrates] as the x axis and initial velocity as the y axis. The concept that is being tested by this question is the students ability to interpret enzyme activity graphs. In order to to answer this question correctly, you need to understand how to interpret what a changing substrate concentration does to an enzymes Vmax. Understanding what initial velocity means is important. You also need to understand what Vmax means, because knowing that will eliminate some of the incorrect answers. Understanding what would cause an enzyme's rate to slow down would enable you to answer this question.

For this question, the correct answer is B, enzyme active sites are filled. This is correct because the enzyme reaches Vmax when the graph is starting to level off. Vmax is reached when the enzymes in the system are all working at maximum rate, which is when all of the enzymes are filled. Answer A, “the substrate is used up,” is incorrect because where the graph levels off, the substrate concentration is not zero. In addition to that, the y axis is initial velocity, which means there would be no time for the substrate to have been used up. Answer C, “the reaction reaches equilibrium,” is incorrect because the graph makes no mention of the reverse reaction, and thus no mention of equilibrium. The graph only illustrates the rate of the enzymes which are performing the forward reaction. Answer D, “the rate of the reverse reaction becomes significant” is incorrect because that would indicate that the graph illustrates a system over time. The y axis shows that the dots mean initial velocity, which means that the reverse reaction would not have time to become significant.

One of the strengths of this article was the testing of both scent detection and scent discrimination.  Olfactory cues are more complex in nature than what can normally be reconstructed in a lab.  Therefore, the authors’ decided to drive home the hypothesis of olfactory lateralization by testing bees on two different aspects of olfaction. 

One weakness of this study was that during the comparison of olfactory receptor cells each of the 10 pairs of antennae should have come from 10 individuals.  Instead, only 7 pairs came from 7 individuals and the other three from three individuals.  This could cause some data discrepancies because all antennae were not collected in the same manner.  Also, 10 pairs of antennae is not a high number considering they added this information to their paper.  The authors might want to gather more data with more pairs of antennae in order to be entirely sure of the correlations.

The University of Massachusetts Amherst is teeming with great faculty, which is what makes it such a great university. All of the great faculty made it difficult to choose one person to write about. However, after searching through the MCB faculty list, I found Dr. Sandra L Peterson. Sandra Peterson is a Professor of Molecular Neuroendocrinology of reproduction at UMass. Sandra Peterson got her BS in Biology at Rutgers University in 1977. She then went on to get her MS in Neuroendocrinology at Oregon State University in 1980. Finally, she followed that up with her PhD in Neuroendocrinology at Oregon State University in 1984.

In addition to being a professor, she is a director at the STEM diversity institute. The STEM diversity institute’s main purpose is to facilitate the diversification of the STEM workforce. They help underrepresented groups enter and rise in the STEM field. Sandra is also a director at the Northeast Alliance for Graduate Education program (NEAGEP). Similar to the STEM diversity institute, the NEAGEP works to recruit and mentor members from minority groups and help enable them to pursue PhDs in the mathematics, engineering, and science.

Shh is an extracellular signalling protein which modulates expression of a number of genes. The Hh protein binds to a transmembrane protein called Patched (Ptch). This binding stops Ptch from inhibiting another transmembrane protein called Smoothen (Smo). When Smo is active, it is able to induce the Gli transcription factors to being transcribing genes. While many of the genes regulated by Hh/Gli are known, further experiments continue to identify new genes.

In “WHOSE BODY IS IT, ANYWAY?”, Gawande discusses the thin and often blurred line between a patient’s autonomy and a doctor’s ability to mediate or even make decisions for patients when they believe the patient is making a mistake. Gawande discusses many situations where a patient’s decisions and what he as a doctor recommends are at odds. Gawande admits it is not always clear what to do in these situations, but states that the current view in the medical world is to allow the patients to decide (212). One situation that Gawande describes involves the patients referred to as Lazaroff, who has an incurable cancer in his spinal cord. The cancer has caused Lazaroff to lose control and ability in his left leg and may progress to paralysis. Lazaroff has only a few weeks to live according to the doctors, however, he still speaks about soon returning to work (209). Perhaps Lazaroff is making light of the situation, but much more likely in his situation, he misunderstands his situation and that his lease on life has been cut short.

There are two main hypotheses regarding the lactose persistence mutation. Firstly, the “culture-historical hypothesis” states that alleles for lactose persistence were low until humans domesticated dairy animals in the early Neolithic and then rose sharply due to the selective advantage it conferred and natural selection. The “reverse cause hypothesis” states that dairy animals were utilized in populations with preadaptive high lactose persistence. Researchers have discovered that lactase persistence likely arouse through convergent adaptation. Scientists studied 470 Tanzanians, Kenyans and Sudanese in a genotype-phenotype association study which focused on three SNPs associated with lactase persistence “These SNPs originated on different haplotype backgrounds from the European SNP and from each other...These data provide a marked example of convergent evolution due to strong selective pressure resulting from shared cultural traits—animal domestication and adult milk consumption. (Sarah Tishkoff et al., 2007)” This case of convergent evolution with African and European populations is strong evidence that human populations are evolving. Mutations likely arose independently in these two populations that allowed for lactase persistence. Since the mutations conferred a selective advantage, these alleles were favored by natural selection and increased in frequency.

In the beginning of December, New Horizons (one of NASA’s space probes exploring the universe) took an image of a group of stars called the “Wishing Well” as well as objects from the Kuiper Belt which is the farthest from Earth that an image has been captured (almost four billion miles away). Assuming the lenses in the camera used by the spacecraft were very high­tech, it should contain both converging and diverging lenses. These lenses work together to create a real, inverted, negative magnification, clear image. In the future, New Horizons is set to explore more of the Kuiper Belt and other objects out in deep space. Many do not know the inner workings of telescopes and how we build telescopes to be able to magnify images of distances more then four billion miles away. Lenses are in our every day lives, they include classes, phones, televisions, and more. Each designed differently for their different purposes, but all taking to account reflection, refraction and the reation of an image.