hw2 - Genetics Homework #2 due in lecture Tuesday, Aug. 19...

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Unformatted text preview: Genetics Homework #2 due in lecture Tuesday, Aug. 19 1. Suppose that a particular enzyme deficiency causes the Perturbed syndrome. A man has a perpetually perturbed sister, but he, his parents, his grandparents, and three other sisters usually remain calm. Discussions with relatives in his wife's family reveal that the syndrome is not likely to be present in her family, although some relatives recall that the brother of his wife's paternal grandmother was usually perturbed. Diagram and analyze the relevant pedigree to determine (a) the genetic basis for inheriting the perturbed trait; and (b) the highest probability that, if this couple has a child, the child will be perturbed (i.e. what is the chance of the worstcase scenario occurring?). 2. Genes L, N, and S are independently assorting and control the production of a purple pigment. a. Suppose that L, N, and S act in the following pathway: X L N Y Z S purple (Substances X, Y, and Z are all colorless.) The alternative alleles that give abnormal functioning of these genes are designated l, n, and s, respectively. A purple LLNNSS is crossed with a colorless llnnss to give a purple F1. The F1 is selfed. What proportion of the F2 individuals is colorless? b. Suppose instead that a different pathway is utilized. In it, the S allele produces an inhibitor that prevents the formation of purple by destroying the ability of N to carry out its function. The mechanism is as follows: L N Q R purple S (inhibitor) (Substances Q and R are both colorless.) A colorless LLNNSS individual is crossed with a colorless llnnss, giving a colorless F1. The F1 is selfed to give an F2. What is the ratio of colorless to purple in the F2 individuals? c. How would you evaluate which of the biochemical pathways hypothesized in parts (a) and (b) is more likely? 3. Exploring Genomics exercises from Chapter 7 (page 193). Skip Exercise 1, part 4. Answer all other questions. ...
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This note was uploaded on 09/12/2008 for the course BICD 100 taught by Professor Nehring during the Spring '08 term at UCSD.

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