2006problemset4key

2006problemset4key - Problem Set #4 KEY BICD 100 W' 06 (L....

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1 Problem Set #4 KEY BICD 100 W’ 06 (L. Smith) 1.) To identify genes controlling coat color in mice, a scientist mutagenizes a pure-breeding line of wild type black mice, and screens the F 2 generation for mice with altered coat color. Four recessive coat-color mutations are recovered: brown (genotype b/b), yellow (genotype y/y), and two different whites (w1/w1 and w2/w2). Mice heterozygous for any one of these mutations (i.e., B/b, Y/y, W1/w1 and W2/w2) are all black. The following crosses are performed to determine whether these mutations are in the same gene or different genes. In each case, the F 2 generation is produced by crossing F 1 mice to each other. parental phenotypes F 1 phenotype F 2 phenotypes _____ i. brown X white #1 black 9 black: 3 brown: 4 white ii. brown X white #2 black 9 black: 3 brown: 4 white iii. brown X yellow brown 3 brown: 1 yellow iv. yellow X white #1 black 9 black: 3 yellow: 4 white v. yellow X white #2 black 9 black: 3 yellow: 4 white vi. white #1 X white #2 black 9 black: 7 white a . How many different genes controlling coat color have been identified? Three b. Which pair(s) of mutations are in the same gene, if any? The brown and yellow mutations must affect the same gene because they fail to complement each other. c. What are the genotypes of the black, brown and white mice in the F 2 progeny from cross ii? (In answering this and subsequent questions, if there is more than one genotype for a given phenotype, show them all, but feel free to use “B/-“ to indicate that the genotype is B/B or B/b, etc.). Black mice are B/- W2/-; brown mice are b/b W2/-; white mice are B/- w2/w2 and b/b w2/w2. d. What are the genotypes of the brown and yellow mice in the F
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This note was uploaded on 04/17/2008 for the course BICD 100 taught by Professor Nehring during the Spring '08 term at UCSD.

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2006problemset4key - Problem Set #4 KEY BICD 100 W' 06 (L....

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