AnswerKeyP2F08 - 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 21. . The mean for Prelim #2 is 57. QuestiOn 1: Jessica, Dr Nero Question 2: Zhen . QuestiOn 3: Megan Question 4: Satyaki, Caroline _ - Question 5: Gabe . Question 6: Mohan, Patrick - Améwms 1 /_________., BIOGD 281 Second Preliminary Exam October 30, 2008 There are 15 pages to this exam, including this page. Be sure you have a complete set before you begin. Two blank pages for scratch paper have been attached at the end. These may be removed. Put all answers in the boxes or on the lines provided. Only answers in the boxes/lines will be graded. Examinations must be submitted by 12:05; late submissions Will not be graded. Please turn off all cell phones and PDAs. Name Lab Section and TA Total 1. (18 points) In Drosophila, there are three genes, at b and 6, located in region 1%?” m on the polytene map of the 2nd chromosome. Gene b maps between genes a and c. You are interested in determining in which band or bands each of the three genes is located. A diagram of the bands in 22A is shown below: bands: 12 3 4'5 6 7 You X-ray homozygous a+ b+ cJr (wild type) males and cross them to homozygous a b c females. You look at the progeny and recover several exceptional F1’s of the following types a b c, a b, b c, a, b, and c. A. (2 pts) What property of deletions allowed you to find these exceptional progeny? P51?” lflfgfl 66/ B. (2 pts) Briefly indicate why you didn’t obtain any flies mutant for both a and c. 57° mat/J q/fifi éz/ ole/9W 3/2762 He je’fiawar 62 m: - Wat/J refill/“c é‘flma/(‘S' if 48%?» Wr/ Mfi/Vé/ C. (6 pts) You extract the chromosomes from these mutants and examine region 22 in their polytene chromosomes. When you record which band(s) are missing, you obtain the following results. _ l- ' E- Indicate below which band or bands each/gene/maps to: [l I [t \‘T 17 22A 42E 0 m 1:- 510M 7 D. (8 pts) You repeat the irradiation of wild type males. This time you mate them to female homozygous for a b c and also d, which is a gene on the third chromosome. To your surprise, you recover a fly mutant for both a and d. The likelihood of simultaneously deleting (1+ and 61+ should not be considered since this is extremely rare. You cross the a 6! double mutant fly to normal wild type flies. Then you testcross F 1 males to females from a laboratory stock homozygous for a b c and d. Indicate the percent of surviving progeny flies with the indicated phenotypes: a+b+ c+d+ i3 (3&5) a+b c+d+ C9 (1 b c d [4 (1 [9+0 0’ C9 (1+1) 0 d 0 a+b c d+ 0 a b+c+d+ O a b+c+d Zé (é’é) a+b+c d 42 a+b+c (1+ 0 a b c+d+ a b c+d & C5 a+b+ c+d [Z (75") r _‘ a+b c+d C) a b c d+ [HQ [may l a b+c d+ ( 2 2. (16 points) On yeast chromosome 14 there are three genes with the following map: 10 mu lO mu et Where. indicates the centromere. You irradiate a wild type yeast strain and recover a pericentric inversion with breakpoints just to the left and right of ad and met respectively as shown by the arrows above. A. (6 pts) You cross yeast with this pericentric inversion to a laboratory strain mutant for ad his and met. The diploids are allowed to sporulate. What percent of the haploid colOnies arising from these spores will have the indicated genotypes? ad‘L his+ met+ SC) ad his met 5 ad+ his met 0 0 0 ‘__0_ ad his+ met+ ad+ his+ met ad his met+ B. (4 pts) Again, in the absence of double crossovers, what percent of the spores you collect will fail to germinate? C. (6 pts) Now consider ju_st the double crossovers one between ad and his and the other between his and met. Indicate for a single ascus of each type of double cross over tetrad, the genotype(s) of any Viable spores, and how many spores fail to germinate. — Viable genotypes number of dead spores +'*+».M+MWJ£+ & f ”' ’ mi, My M 2 strand DCO 3 strand DCO 4 strand DCO ~ - mm ‘7‘ 3. (16 points) In phage T4, the following data were obtained from siX two point crosses involving rapid lysis (r) mutants: A. (4 pts) Using this data, construct a map of the chromosome containing the r mutants. B. (4 pts) In the cross of r1 X r2, how many wild type plaques were seen when the progeny phage were plated on a lawn of bacteria? Explain your answer. C. (4 pts) Indicate Whether the cross and the analyses of the progeny were done at a high or low MOI. Mi/ MW Cross Progeny Testing D. (4 pts) Given the map you constructed in Part A, list the percentage of triple mutant phage you would obtain from the following crosses. Remember there is essentially no interference in T4 crosses. r1+ r2+ r3+ x r1 r2 r3 i5“ (9‘. (90; 5“ r1 r2+ r3+ X r1+ r2 r3 ANM‘ r1 1‘2'r3+ X r1+ r2+ r3 4. (16 points) The following is the circular map of the E. coli chromosome derived from Hfr gene transfer data. Also shown are the positions of two different integrated F factors designated Hfr H (for Hayes) and Hfr L (for Lederburg). The arrows indicate the direction of transfer. .v i’ O \ 5 10 L pro H , lac ‘ 15 85 thi 25 pAR " gal. 70/ his The times indicate map positions determined by a third Hfr strain with an F factor inserted at the pro gene (time 0). A. (12 pts) You make two crosses, one with Hfr H (cross 1) and one with Hfr L (cross 2) interrupting the matings at 15 minute intervals. The genotypes of the strains are as follows: Hfr H pro+ pur‘L his+ thi+ strS Hfr L pro+ pur+ his+ thi+ strS F' pro* pur' hiS' thi‘ strr Fill in the following two tables with a + if recombinant colonies are present. Leave it blank if no colonies appear. In this experiment basic media = minimal + proline + purines + histidine + thiamine + streptomycin 1, (6 pts) Cross 1: (70/) Basic media minus Time (min) Proline Purine Histidine Thiamine O 15 30 45 -. 4— 60 + y T . vs +r— _ + 90 -—I— 4— '4" 4" 2. (6 pts) Cross 2: ((40 0 Basic media minus Time (min) Proline Purine Histidine Thiamine 10 B. (4 pts) Your student wishes to repeat your results but inadvertently mixes the two Hfr strains together before mating them with the F" bacteria. Fill in the table below with the data this poor student would obtain. I Basic media minus 40 Time (min) Proline Purine Histidine Thiamine 0 -—- 15 -_ + 30 l-_ + 45 m + so + 75 1+ 90 l- .+ + 5. (16 points) The following is a simplified'version of one of the slides from the lecture on F' elements in E. coli. It shows the extent of the pieces of the E. coli chromosome carried by several F ' strains labeled A through I. These F' strains were all derived from a Wild type Hfr strain. 11 12 A. (8 pts) You have mutagenized a wild type F' strain that is rec" and recovered several methionine auxotrophs (met'). 1. (4 pts) Assume a met" auxotroph is recessive. Which of the F ' strains will give colonies on minimal media when crossed with the met' F ' strain? A/E WC; 2. (4 pts) Now assume the met' auxotroph is dominant. Which of the F' strains will give colonies on minimal media when crossed with the met" F ' strain? [7(9fl6— 13 B. (8 pts) Note that there are two genes, met B and met E that are closely linked on the E. coli chromosome. You move your recessive met" mutant from part A of this problem onto the F' element in strain A replacing the wild type allele on that element. Assume your met' mutant is in the met B gene. You now cross this F' strain with your met' allele to two F ‘ strains. One F' strain is mutant for met E and the other F' strain has an independently derived mutation in met B. Fill in the table below with a + if colonies appear on minimal media or a — if there are no colonies on minimal media. Your F ' met' crossed to: t F ‘ met B‘ rec‘ F' met E' rec‘ F ' met 8' rec+ + F” met E‘ rec+ ' l4 6. (18 points) You have isolated three mutants (joe, sam, and bob) in E. coli and tentatively mapped them using conjugation. Much to your surprise the three mutants are transferred at exactly the same time so their order cannot be determined. You decide to map them using phage P1 and generalized transduction. You grow phage on wild type E. 0011', then infect a triple mutant strain of E. 0012'. You select for 2,500 sam+ transductants. When the sam+ cells are replica plated you obtain the following data: Genotype Number sam+ joe bob 1500 sam+ joe bob+ 740 sam+ joe+ bob 10 joe+ bob+ 2—50 sam+ A. (4 pts) What is the order of these three genes? B. (6 pts) What are the cotransduction frequencies between: sam and joe & [fl sam and bob ’2» 3 ‘7é joe and bob C27» '7‘ {It/Z 15 C. (4 pts) In the box below, give two reasons why there are so many sam+ j oe bob transductants. D. (4 pts) In the box below, give two reasons why there are so few sarn+ joe+ bob transduetants. ...
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AnswerKeyP2F08 - If you have any questions about an exam...

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