Human Genetics 34 Points Total Essay

Decent Essays

Principles of Human Genetics 34 points total
Homework #5 is due on November 15, 2016.

Please read Rana et al. (1999). You may also find parts of chapter 6 in your textbook helpful. Then answer the following questions. You will also use some datasets to conduct your own analyses.

1. Rana et al. (1999) are interested in human pigmentation variation. What locus did they sample and why? What populations did they sample? Did they include any outgroups? (4 points)

Rana sampled the melanocortin 1 receptor (MC1R) which regulates the expression of pheomelanin and eumelanin. Both are thought responsible for skin pigmentation as these receptors are linked to coat color in a variety of mammals. Therefore, the study investigates how variations in MC1R affect skin color in human populations from different geographic regions. Sequences obtained from 121 individuals of whom were predominately Asian populations followed by African, and Europeans characterized the results in this publication. The study accounts for outgroups such as other mammals and especially non-human primates.

2. How did Rana et al. test for signs of selection using data from more than 1 species? What were the results? (4 points)

Sequences of the MC1R ascertained from human populations were compared with other mammals by constructing a parsimony tree to illustrate key amino acid substitutions. Dn:Ds (Ka:Ks) ratios denoting the number of nonsynonymous substitutions/non-synonymous site and the number of

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