Argument Prompt
Shenk
mentions that single genetic mutations, such as Huntington’s disease, account
for 5 percent of the total disease burden in developed countries and how it is
important not to let those diseases give the wrong impression of how healthy genes
work (Pg 25). Yet mutations such as substitution leads to no frameshift and can
possibly not affect the primary structure of protein. In this case, there is variation
for evolution by creating an ultimate source for new genes. The phenotype of an
organism can be affected by small-scale changes involving individual genes. In
what ways can this type of mutation benefit humans in the “dynamic development”
idea that “The Genius in All of Us" describes and how does this relate to the
core biology theme of evolution? Response may also include explanations about the themes of continuity and change and the relationship between structure and function. Refer to chapter 17 concerning point
mutations. Also consider how the title “The Genius in All of Us” can refer to people
who are part of the 5 percent of the total disease burden.
Kirk Chiu- (krkpchiu@gmail.com)
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ReplyDeleteA base-pair substitution is a type of mutation that exchanges a single base-pair for a different one. There are three possible overall outcomes that can come from this type of mutation: a silent mutation, a nonsense mutation, and a missense mutation. A silent mutation is a base-pair substitution in which the switched nucleotide does not change the amino acid due to the redundancy of the genetic code. A nonsense mutation occurs when the new nucleotide is a stop codon which ends translation prematurely and usually ends up with a nonfunctional protein. A missense mutation is a mutation where the altered codon codes for a different amino acid (Campbell 344-345). The latter is what can cause improvements in humans. According to Brown University, mutations are the ultimate source of variation as these mutations would change the amino acid sequence of the protein which will change the function of the protein as the structure of the protein matches its function. Without variation there could be no evolution so mutations are extremely important to evolution. http://biomed.brown.edu/Courses/BIO48/4.Mutants.Link&Recomb.HTML These mutations might give a selective advantage the organisms that have it which would allow these organisms to survive, reproduce, and pass on the genes that have this selective advantage. The environment would then eliminate those that could not survive and reproduce which is how natural selection works. At least that's what old G+E genetics stated.
ReplyDeleteIn Shenk's new GxE model, he states that the environment interacts with the genes and that collectively they cause a trait. In the case of GxE, a beneficial base-pair substitution would not cause as big of an impact due to the fact that genes do not dictate traits directly. However, this does not mean that genes do not have an impact upon traits as Shenk describes genes as “volume knobs and switches…[that] can be turned up/down/on/off at any time—by another gene or by any minuscule environmental input” (39). Therefore, if an individual has a beneficial point mutation, then the gene can be turned up in order to maximize its benefits and help survive and reproduce. This clearly relates to evolution because the beneficial point mutation would be a selective advantage that would help the individual survive and reproduce to pass on that beneficial gene. Shenk uses the example of a point mutation causing a disease in order to prove his point that even if a gene defect is responsible for many problems that the opposite is not true: the normal form of a gene is not directly responsible for normal function.
-Josh Choi (joshchoi95@yahoo.com)