AnswerKeyP2F06

AnswerKeyP2F06 - If you have any questions about an exam...

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Unformatted text preview: If you have any questions about an exam problem please see the TA that graded that problem. ' " - If you want your exam regraded you must submit it to Debbie Nero. I reserve the right to regrade the entire exam. Please include a note with the submitted exam telling me which problem you are questioning. . Regrades for Prelim 2 may be submitted through noon, Friday, November 17. The mean for Prelim #2 is 70. Question 1: Gerry Question 2: Ed Question 3: Suzy & Dr Nero Qliésti‘iihu: Adam " ' Question 5: Alex Question 6: Madeline & Maho BIOGD 281 Second Preliminary Exam October 26, 2006 There are 11 pages to this exam, including this page. Be sure you have a ' complete set before you begin. Two blank pages have been attached at the end for scratch paper. Put all answers in the spaces provided. Only answers in the boxes or on the lines will be graded. Name Lab Section and TA Total l. (16) The following crosses were made in yeast: A. (8) leu+ ad X1611 ad+ gave the following asci In the box below, draw a map of these two genes showing the position of any centromere(s). ff 7:1 / W + 4%” I [rm/0 W B. (8) leu+ rib x leu rib+ gave the following asci. (Leu is the same gene as in part A.) In the box below, draw a map of these two genes showing the position of any cent1'01nere(s). 2. (16) A heterokaryon was established in the fungus Aspergz'llus nidulans between a haploid strain that was nic+ leu+ met” trp' and a haploid strain that was nic' leu' 1net+ trp+. Then a diploid strain was selected from the heterokaryon, and after any mitotic crossing over the following eight haploid strains were obtained from conidial isolates. Classes 1 through 7 were equally frequent but class 8 was very rare. V l nic+ leu+ met up 2 nic+ leu+ met+ trp+ 3 nic' leu+ met" up 4 nic' leu' met+ trp+ 5 nic' leu+ met+ trp+ 6 nic+ leu‘ met+ trp+ 7 nic‘ leu" met' trp' 8 nic+ leu' met+ trp' A. (10) In the box below, draw a map of the four genes showing which genes are linked and which genes are on different chromosomes. B. (6) Between which pair(s) of genes did a mitotic crossover take place? 3. (20) The following figure shows map distances observed for genes in one chromosomal region (the open circle represents a centromere) A new paracentric inversion is made that carries a recessive mutation, d, at the D locus. Its proximal breakpoint lies between B & C, 1 map unit fiom B and its distal breakpoint lies between G&H, 1 map unit from G. A heterozygote for this inversion and the wild type gene order mates with a dd individual homozygous for the inversion. A. (5) Draw the pairing configuration of the chromosomes in the heterozygote at metaphase of meiosis 1. Include gene symbols and centromeres. B. (5) In the absence of multiple crossovers, what is the probability that a dd offspring will have one homolo g with the wild type gene order? +5" C. (4) In the absence of chromatid interference, What is the expected ratio of the indicated chromatids following double crossover events. Non crossover chromatids l l l Balanced crossover chromatids mi/ Dicentric chromatids Acentric fragments D. (6) Given the possibility of double crossovers, What is the probability that a dd individual will have a Wild type gene sequence? w a mail?» 3360" Ei— ,0/ C300 " Jxlee, MMFWOU/ I ,0/ 3;; 4. (16) In E. coli, the following Hfr strains donate the genes in the orders shown below: _ m— SAW A. (8) Draw a map of the genes in the F+ bacterial chromosome and show the positions and orientations of the F factors in your map as 9. B. (4) In strain 1, there is 10 minutes between the transfer of genes E and B. In the box below, indicate how many minutes there are between the transfer of genes B and E in Hfr strain 4? Briefly explain your answer. C. (4) In strain 2, there are 20 minutes between the transfer of genes L and G. In the box below indicate how many minutes there are between the transfer of genes L and G in strain 1. Briefly explain your answer. 5. (16) The following is a map of three T4 genes,‘ r am and h. r 6 am 50 h There are 6 map units between r and am but it shows independent assortment with both r and am. You carry out a three point cross between two strains: + + + ramhxr am It You obtain eight phenotypic classes among the progeny phage including the parentals. In the box below list the eight classes and their numbers (n=1000). Classes 1 & 2 should be the parentals. 6. (16) In a transduction experiment with phage P1, the donor was c+ d+ e+ and the recipient was 0 d e. The four classes of transductants from this cross are shown below. 2 B. (3) If possible, give the co-transduction fiequencies for genes: candd G.12- [Jig cande «27 L + e and d Cami do 725‘ C. (5) Which cotransduction frequency represents the greater actual distance between genes? Briefly explain your answer. +£17flw ,1). -+ 3 % WW D. (4) Give two reasons why there are so many c+d e transductants ...
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This note was uploaded on 07/17/2009 for the course BIO 2810 taught by Professor Fox/nero during the Fall '07 term at Cornell.

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AnswerKeyP2F06 - If you have any questions about an exam...

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