Bio97_09+L15

Bio97_09+L15 - Linke Ge s and Ge d ne ne Mapping I I Bio...

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©2009 C. Brachmann 1 Linked Genes and Gene Mapping II Bio Sci 97, 2009 Dr. Carrie Brachmann Office hours Mondays and Fridays 12-1:30 (10/30, 11/2, 11/6, 11/9, 11/13, 11/16) AND Weds, Dec 2 12-1:30, 3-4 4213 McGaugh Hall I will post old test questions at the end of each lecture, to be answered at the beginning of the next lecture. Please keep up with the reading as assigned in the syllabus and work through the problems.
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Your graduate thesis project is to determine whether dp and e are linked. For some reason, geneticists have never set up a cross to test this. 4pt dp = dumpy wings, recessive dp + = normal wings e = ebony body, recessive e + = normal body a. You testcross the F1 female that is heterozygous for both loci. Fill in the blanks for the progeny you observe: genotype of Phenotypes of progeny maternal gamete # flies normal wings, normal body dp+ e+ 265 dumpy wings, ebony body dp e 235 dumpy wings, normal body dp e+ 2270 normal wings, ebony body dp+ e 2230 b. Draw the genotypes of the flies in the testcross: female: dp e+/ dp+ e male dp e/ dp e c. What is the frequency of recombination? 265 + 235 = 500/5000 = 0.1 =10% Answers to questions at end of last lecture
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©2009 C. Brachmann 3 You have been given the task in your Bio199 research lab to determine whether the autosomal Drosophila genes bl and vg are linked. bl = black body, recessive bl+ = gray body vg = small wings, recessive vg+ = normal wings The testcross of an F1 female that is heterozygous for both genes yielded the following numbers of progeny: 429 normal wings, black body 432 small wings, gray body 68 normal wings, gray body 71 small wings, black body A) In the double heterozygote F1 female, were the recessive alleles in cis or trans? B) Indicate the genotype of this F1 female, using correct nomenclature. C) Indicate the genotype of the testcross male, using correct nomenclature. D) What is the map distance, in map units, between the vg and bl loci? trans vg+ bl/ vg bl+ vg bl/vg bl 139/1000 = .139 = 13.9 mu or 14 mu
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True or False: Recombination frequencies are the same for cis and trans heterozygotes TRUE If there is one crossover in every 50 cells undergoing meiosis, this is equivalent to: A. 0.5 map units B. 1 map unit C. 10 centiMorgans D. 2% recombination E. 0.2 map units Two loci are 22 map units apart. How many centiMorgans apart are they? What gametes are produced by an individual with the genotype bD/Bd if the genes are a. completely linked bD and Bd b. located on different chromosomes bD bd BD Bd 22 cM from 49 meioses w/out X-over get 4 parentals each = 4 x 49 = 196 from 1 meiosis with X-over get 2 parentals and 2 recombinants 2 recombinants/200 total progeny = .01 = 1% = 1mu = 1cM
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©2009 C. Brachmann 5 Which of the following statements is true? I.
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Bio97_09+L15 - Linke Ge s and Ge d ne ne Mapping I I Bio...

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