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Homework03key - BIS101-003/Engebrecht 1. In a testcross of...

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BIS101-003/Engebrecht 1. In a testcross of a female Drosophila heterozygous for three linked recessive genes, the following phenotypes of progeny were obtained: a + b + d 442 a b d + 435 a + b d + 12 a b + d 11 a + b d 52 a b + d + 46 a + b + d + 1 a b d 1 Total 1000 Construct a map of the genes and calculate interference. 1) Determine parentals: a+b+d and a b d+ 2) Determine double co classes: a+b+d+ and a b d; therefore, d must be in the middle 3) Calculate distance between a d: 12 + 11 + 1 + 1/1000 = 2.5 cM 4) Calculate distance between d b: 52 + 46 + 1 + 1/1000 = 10 cM a 2.5cM d 10cM b 5) Interference (I) = 1 – coefficient of coincidence (observed d co/expected d co). Expected d co = .025 x .1 = .0025. Observed d co = .002 (2/1000). I = 1- .002/.0025 (= 0.8) therefore I = 0.2 2. Three genes of corn, R, D, and Y, lie on chromosome 9. The map of the three genes is: R D Y 10 20 a) In a testcross of a trihybrid plant RDY x rdy rdy rdy, how many RdY rdy plants would be expected in a progeny of 1000 if there was no
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Homework03key - BIS101-003/Engebrecht 1. In a testcross of...

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