MCB164+MT1+S06+KEY

MCB164+MT1+S06+KEY - Name MCB164 Spring 2006 Page 1 of 8...

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Name_______________________________ MCB164 Spring 2006 Page of 8 FIRST MIDTERM April 20, 2006 Question Points Score 1 18 2 12 3 8 4 12 5 6 6 10 7 12 8 12 9 10 Total 100 This examination is closed book. There are 8 pages to the exam. Please count them before you start to make sure all are present . Please write your name on each page of the exam . Answer each question in the space provided. If additional space is required use the back of the page and indicate clearly that you continued your answer on the back. Do not attach additional pages. GOOD LUCK! Student authorization: I authorize the instructor to return the graded exam to me in the main office or to distribute it in the bin for me to pick up. Signature _____________________________ Date_____________________ 1. (18 points) You have carried out a screen for mutants that are more sensitive to high doses of ionizing radiation (e.g. rads) than an isogenic wild type strain of budding yeast. 10 independent 1
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Name_______________________________ MCB164 Spring 2006 Page of 8 mutants came out of this screen. Five of these mutants were isolated in a MATa strain background and you call them m1-m5; mutants m6-m10 were isolated in a MATalpha strain background. The phenotype of diploids generated from pairwise crosses (m1…m5) x (m6…m10) are shown in the table below where “M” represents a diploid exhibiting a mutant phenotype and “+” represents a wild type phenotype. WT m6 m7 m8 m9 m10 WT + + + + + + m1 + + M + M + m2 + + + + + + m3 M M M M M M m4 + M + + + + m5 + + + + M + A) From a first approximation, group all mutants that are most likely alleles of the same gene. From a first approximation the genes could be grouped as follows: 1. m1, m7, m9, m5 2. m4, m6 notes: i) if both m7 and m5 turn out to be allelic then complementation of these two mutations suggests intragenic noncomplementation. If m5 is not allelic to m1, m7 or m9 then the failure of m5 and m9 to complement would indicate second-site noncomplementation. Segregation analysis is required to distinguish between these two possibilities. ii) m3 is apparently dominant so a complementation test is not possible. Thus we do not know if m3 is in group 1, group 2 or neither. B) Based on the data above, circle the correct word to compete the following sentence: Mutations m1 and m6 (complement / fail to complement ) each other. Question 1 continued on next page… C) You dissect 60 tetrads from the diploid formed by crossing m4 x m6 and observe the following numbers of tetrad types by following the mutant and wild type phenotypes: 2
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Name_______________________________ MCB164 Spring 2006 Page of 8 # of tetrads segregation pattern 11 PD 8 NPD 41 TT i) What is the ratio of wild type to mutant phenotypes among these different tetrad types
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This note was uploaded on 04/04/2010 for the course MCB 164 taught by Professor Burgess during the Spring '08 term at UC Davis.

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MCB164+MT1+S06+KEY - Name MCB164 Spring 2006 Page 1 of 8...

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