Jakob_Week1 Key

Jakob_Week1 Key - b Draw a map that shows distances in map...

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Week 1 Questions 1. A three-point testcross was made in corn. The results and a recombination analysis are shown in the display below, which is typical of three point testcrosses (p = purple leaves, + = green; v = virus-resistant seedlings, + = sensitive; b = brown midriff to seed, + = plain). Study the display and answer parts a through c. P +/+ • +/+ • +/+ X p/p • v/v • b/b Gametes + • + • + p • v • b Class Progeny Phenotype F1 Gametes Numbers p-b p-v v-b 1 gre sen pla + • + • + 3,210 2 pur res bro p • v • b 3,222 3 gre res pla + • v • + 1,024 R R 4 pur sen bro p • + • b 1,044 R R 5 pur res pla p • v • + 690 R R 6 gre sen bro + • + • b 678 R R 7 gre res bro + • v • b 72 R R 8 pur sen pla p • + • + 60 R R Totals: 10,000 1,500 2,200 3,436 a. Determine which genes are linked They are all linked because the recombination frequencies are all <50%
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Unformatted text preview: b. Draw a map that shows distances in map units Calculated distance between v and b is 34.36 m.u. c. Calculate interference, if appropriate I = 1 – observed double crossovers/expected double crossovers I = 1 – 132/(.22 * .15 * 10,000) I = 0.6 v p b 22 m.u. 15 m.u. 2. John and Martha are contemplating having children, but John’s brother has galactosemia (an autosomal recessive disease) and Martha’s great-grandmother also had galactosemia. Martha has a sister who has three children, none of whom have galactosemia. What is the probability that John and Martha’s first child will have galactosemia? (Chapter 2, Q: #31) Use the product rule to calculate the probability that both parents are carriers (+/-) and that the child is -/- p(child has galactosemia) = p(Marth +/-) * p(John +/-) * p(both parents pass – to child) =2/3 * 1/4 * 1/4 = 2/48 = 1/24...
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Jakob_Week1 Key - b Draw a map that shows distances in map...

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