Midterm_IIw06key

Midterm_IIw06key - LS4 MIDTERM II INSTR: L. JOHNSON NAME:_...

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1 LS4 MIDTERM II INSTR: L. JOHNSON Thursday, Feb 23, 2006 NAME:_________________________________ (last) (first) ID #___________________________________ INSTRUCTIONS 1. This exam is 6 pages long. Problem Score Before starting make sure you have all the pages. 1 12 2. No credit will be given for an 2 7 illegible answer. Please write in pen. 3 12 3. You may use a calculator. 4 8 5 16 6 16 7 29 Total 100
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2 Name _________________________________________ID#______________________ (last) (first) (12 pts) 1. In Drosophila, the genes st (scarlet eyes), ss (spineless bristles) and e (ebony body) are linked as shown below on chromosome 3: st 6 mu ss 12 mu e a) Each of these mutants is recessive to the wild type allele. Phenotypically wild type females with genotype st ss e+/st+ ss+ e were mated to triply recessive males. Assuming no interference, what proportion of the progeny is expected to be triply recessive? (1/2)(1-.06)(.12) = .0564 or 5.64% b) Assuming 30% interference, what proportion of the progeny is expected to be scarlet? (1/2)(.06)(.12)(.70) = .00252 or .25% c) Assuming 30% interference, what proportion of the progeny is expected to be wildtype? (1/2)[.12 - (.06)(.12)(.7)] = .0575 or 5.75% (7 pts) 2. In Arabidopsis, seeds from a mutant plant that had extra stamen were treated with a mutagen and the resulting plants were selfed. When the F2 generation was planted, a single plant was identified with the normal number of stamen. a) What type of mutation has been isolated? suppressor b) If this new mutant has no phenotype by itself, what will be the ratio of phenotypes of an F2 resulting from crossing the above normal plant with a homozygous wild type plant and then selfing the F1? 13 wild type: 3 mutant (or extra stamen) 9 m+-s+- wild type 3 m+ s-s- wild type 3 m-m- s+- mutant or extra stamen 1 m-m-s-s- wild type
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3 Name _________________________________________ID#______________________ (last) (first)
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This note was uploaded on 09/30/2008 for the course LIFESCI 4 taught by Professor Ribaya during the Winter '08 term at UCLA.

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Midterm_IIw06key - LS4 MIDTERM II INSTR: L. JOHNSON NAME:_...

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