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wk4ans - Covel Peer Learning LS 4(Rachel Care Week 4 Week 3...

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Covel Peer Learning – LS 4 (Rachel Care) Week 4 Week 3 Material: I. Chi 2 test Pygmy Puffs are colored lavender, pink, or cream. When Ginny crossed truebreeding lavender and pink Puffs, all of the F1 was lavender colored. When she crossed F1s, she observed the following F2s: 53 lavender 18 pink 9 cream a. What is the mode of gene interaction for Puff color? Sum: 80. 80/16 = 5. So the “1” in the ratio will be very roughly 5 18/5 ~3 53/5 ~11 Ratio is close to 12 lavender : 3 pink : 1 cream, therefore TWO genes (L and P) Dominant epistasis, with the L epistatic to P/p b. Do the results of the cross differ significantly from the expected values? Null hypothesis: independent assortment PHENOTYPE OBSERVED EXPECTED |O-E| (O-E) 2 /E X 2 Lavender 53 (12/16)*80 = 60 60-53 = 7 7 2 /60 .82 Pink 18 (3/16)*80 =15 18-15 = 3 3 2 /15 .6 Cream 9 (1/16)*80 =5 9-5 = 4 4 2 /5 3.2 SUM: 80 SUM of X 2 : 4.62 Degrees of freedom: # phenotypes – 1 = 3-1 = 2 p-value: between 0.1 and 0.05 Conclusion: ACCEPT null hypothesis of independent assortment

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2. Linkage mapping Curiously enough, sexual inheritance, crossing over, etc occurs the same way in Hinkypunks as it does in Drosophila . Three autosomal genes in the Hinkypunk have the following map: H region 1 p region 2 k 7 m.u. 23 m.u. a. Give the expected number of Hinkypunks for each phenotypic class: h + p + k + /hpk x hpk/hpk female male 1000 progeny: classes of gametes h + p + k + P h p k P h + p k SCO1 (between h and p) h p + k + SCO1 (between h and p) h + p + k SCO2 (between p and k) h p k + SCO2 (between p and k) h + p k + DCO h p + k DCO frequency of DCO = (recomb freq in region 1) x (recomb freq in region 2) (.07) x (.23) = .0161 can happen two ways though (see phenotypes), so divide by 2: .00805
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wk4ans - Covel Peer Learning LS 4(Rachel Care Week 4 Week 3...

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