03exam1 - MIDTERM EXAM 1 Problem 1. (20 points) The...

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1 MIDTERM EXAM 1 Problem 1. (20 points) The following is a pedigree from a family segregating an exceedingly rare (meaning it won’t be encountered in the general population) inherited form of ovarian cancer . The Xg(a) blood type phenotype, which is determined by two different X linked alleles (X g(a+) dominant to X g(a-) ), is also shown for some of the individuals in the pedigree. Assume that the gene responsible for this form of ovarian cancer is fully penetrant. Use this pedigree to answer the following questions. I II III X g(a-) ?? X g(a+) X g(a-) X g(a+) X g( a-) 12 1234567 123456789 1 0 1 1 (a). What is the most likely mode of inheritance for this type of cancer? What features of the pedigree rule out other possibilities? (b). What are the likely genotypes of the following individuals with respect to blood type and ovarian cancer (O c = ovarian cancer allele, O = non-ovarian cancer allele). If you cannot determine the genotypes definitively, use question marks. (i). I-1: (ii). II-1: (iii). II-6: (iv). II-7: (c). What is the probability that (i) III-2 will have daughters that inherit ovarian cancer? What is the probability that (ii) III-3 will have daughters that inherit ovarian cancer? What is the probability that (iii) III-6 will have ovarian cancer and exhibit an Xg(a+) phenotype? (i). III-2: (ii). III-3:
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2 (iii). III-6:
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3 Problem 2 (20 points) You have identified two different recessive mutations in Drosophila that affect eye color (the alleles are designated a and b ). Recombinational mapping of these mutations tells you that they are at opposite ends of the X-chromosome. You now wish to make a chromosome that bears both of these mutations so you can conduct epistasis experiments. Both of the mutations currently reside on aberrant X-chromosomes (shown at right) that bear translocated fragments of other chromosomes onto their ends, giving each of these chromosomes a unique appearance in the light microscope. (a). Diagram how the chromosomes shown above could be used to generate a chromosome bearing both the a and b eye color mutations. Specifically, you should diagram these chromosomes in metaphase I of meiosis in the female that gives rise to the chromosome bearing both mutations and show the 4 products of the meiosis.
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This note was uploaded on 04/15/2008 for the course GENOME 371 taught by Professor Unsure during the Spring '03 term at University of Washington.

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03exam1 - MIDTERM EXAM 1 Problem 1. (20 points) The...

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