23. Given the information that you have been provided about the nature of the mu
ID: 252489 • Letter: 2
Question
23. Given the information that you have been provided about the nature of the mutation that gave rise to the blue iris allele, determine the likelihood of a backward mutation occurring in a genome to create a brown eye allele starting from a blue eye one. What sort of mutation would need to happen? Is this difficult to achieve?
24. A recent survey of published work from 1930 to 1990 showed that the non-paternity rate is currently about 2–3% in western society (not the 10% commonly reported by popular and scientific literature) (Voracek et al., 2008). Meanwhile, the estimated rate of mutations in humans is 2.5 × 10-8 mutations per nucleotide site or 175
mutations per diploid genome per generation (Nachman & Crowell, 2000). Weigh this evidence in determining whether you believe that Ryan is Evan’s son.
25. While most eye color researchers accept that two blue-eyed parents can have a brown-eyed child, most of the original reports in the scientific literature date back to the early 1900s. Here is an example: “Blue x blue as a rule gives only blue. However the rule is not without exceptions. In one case a man with brown eyes was born of blue-eyed parents. Another instance was communicated by a gentleman who stated that both his parents had light blue eyes. Of their seven children all had blue eyes except one sister whose eyes were described as brown or dark hazel. Pearson gives one instance in which one member of a family of six children born of blue-eyed parents had dark brown eyes like those of the father’s maternal grandfather” (Holmes & Loomis, 1909). What’s missing from this type of evidence to be convincing? How would this type of phenomenon be investigated today?
26. According to a 2002 Loyola University study in Chicago (Grant & Lauderdale, 2002), almost 60% of people born in North America at the turn of the last century had blue eyes. By mid century, that number had dropped to a third. Today, it is 1 in 6 Americans (Belkin, 2006; Starr, 2010). Propose a hypothesis to explain this phenomenon.
27. Assuming that the mutation that causes people to have blue eye arose 6,000 years ago (Eiberg et al., 2008; “Blue-eyed humans,” 2008), and given that at the turn of the last century more than half of Americans had blue
eyes, it can be assumed that this mutation is extremely successful. It must confer an advantage. Hypothesize why evolution might have favored the selection of blue eye color. What advantage might it confer? Think of the different mechanisms of evolution that could result in this observation. For explanations that rely on natural selection, specify whether it may be a case of sexual selection.
28. How could this information about the genetics of eye color be used by forensics experts and archeologists? What are some of the challenges of using this technique in these fields?
NATIONAL CENTER FOR CASE STUDY TEACHING IN SCIENCE Part V-Three Hypotheses Following their hypotheses. reflections, Alexia and Evan contacted Dr. Barry Starr at Stanfond University to confirm their three Hypothesis 1:A Mutation Genetics is complicated by the fact that genes don't always stay the same.[.] Our DNA copying machinery is perfect but it still will make an occasional mistake. If that mistake happens in sperm or egg cells, it will get passed on. necarly have a brown-eyed child. [ And if tche change is in the right place in che blue eye gene, blue-eyed parents can now Genes for things like blue and brown eyes are very, very similar. In fact, they are really just same gene. L..] So, to turn a blue eye gene into a brown eye genc, you may only need to change a single letter n.d.) Hypothesis 2: Epigenetic Effects Dr. Starr also offered an alternate hypothesis. Sometimes a gene can be read in one person but is unreadable in another. What happens if a gene is unreadable in a parent but a child's cells can read it? That's right, a blue-eyed parent sometimes what your mom eats while she affect your Scientists did an can have a brown-eyed child. Believe it or not, is pregnant can affect your hair color. Well, if you're a mouse, anyway... experiment where they fed a mouse one food and her pups were black. A different food resulted in or T's were the same berween the pups. What happened? The food ended up lyellow] pups. And all of the A, G, C, attaching little chemical groups called methyls to the DNA. These methyls made the gene unreadable. So even th genetics would predict the same color pups, the environment changed the ourcome (Starr, n.d.) Hypothesis 3: Genetic Complementation Alexia and Evan also contacted another biologist, Ky Sha. while they were at Stanford University ABMelanin Because eye color is determined by many genes, it is possible that each gene product collaborates to synthesize melanin as though they were stations in an assembly line (in other words, the gene products work in series; this is called a biochemical pathway). If this A+BMelanin A-B ? Melanin is true, different enzymes work one after the other on intermediates in the assembly line. If an enzyme working Parent 1 Parent 2 on the melanin pigment ahead of them "breaks down," then all the enzymes downstream on the assembly line cannot do their job. The assembly line stalls. Imagine that Parent 1 has a mutation in Enzyme 1 (on both chromosomes) that prevents the formation of melanin. Parent 2 has a different mutation (also on both chromosomes) that affects a station more downstream in the assembly line, but Parent 2 is also not able to put ABMelanin Child BMelanin parents combine their genes to produce a child, the child inherits one production line that breaks down at Enzyme Dr. Barry Starr is a biologist at Stanford University. While the comments attributed to him are taken from an article he has written (as indicated in the references to this part), this case is a work of fiction. It is not based on Dr. Starr's actions or comments in response to this particular situation Ky Sha is a biologist at Stanford University. While the comments attributed to him are taken from an article he has written (as indicated in th references to this part), this case is a work of fiction. It is not based on Mt. Sha's actions or comments in response to this particular situation. Page More than Meets the Eye" by Annie Prud'homme-GénéreuxExplanation / Answer
23.For a blue-eyed parent to give birth to brown -eyed offspring the mutation should occur in OCA2 gene which controls eye colour. The mutation turns off the mechanism of the production of melanin in the Iris. This may give rise to brown eyes if TT is dominant. If the blue eyes is a recessive gene in the parent then the offspring will have brown eyes which is a dominant gene.
24.If there is 175 mutation per diploid gene then there is every possibility that Ryan is Evan's son.
25.That the gene HERS2 with TT keeps being dominant through generation is not taken into consideration in the experiment. It is this TT that gives rise to the brown-eyed offspring.
26.The hypothesis of mutation works in this phenomenon where one out of every six children would get a brown eye.
27.The people of America who choose to have children with blue eye rely on sex selection. When both parents with blue eye produce offsprings with a blue eye, it is genetic complementation that plays a major role. The genes take a biochemical pathway where the genes OCA2 prevent the expression of TT thereby giving rise to blue-eyed children.
28.Forensic experts can use the genetics of eye colour by using the DNA left at the crime scene. archaeologists can use the DNA from teeth and bone that do not decay easily to determine the eye colour.
Related Questions
drjack9650@gmail.com
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.