2010 exam with answers

2010 exam with answers - EXAM 1, BIOSCI 20192, 2010 _ Name...

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EXAM 1, BIOSCI 20192, 2010 ___________________________ Name The epidemic of HIV infection since the 1980’s has lead to tremendous efforts by the research community to understand how the virus infects human immune cells. In addition to this research, mostly performed by virologists and immunologists, geneticists took another approach. They noticed that, despite the high rate of HIV infection in the gay community, there were certain people who engaged in high risk behavior and nevertheless never became infected. Geneticists hypothesized that there might be something special about these people that made them less susceptible. Indeed, when researchers took lymph cells from one San Francisco man, Fred L., (who identified himself as a high risk individual due to his lifestyle/sexual practices) and exposed them to HIV virus in a lab dish, the cells did not become infected! This was a very exciting result, and made scientists anxious to know the cause of Fred’s natural resistance to HIV. Geneticists asked Fred for information about his family, and all the members still living were asked to donate cells to test for resistance to HIV infection. In the pedigree on the next page, the solid circles and squares indicate that cells were completely resistant to infection. Circles and squares that are shaded indicate that cells were partially resistant to infection. Open circles and squares indicate that cells were completely susceptible.
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EXAM 1, BIOSCI 20192, 2010 ___________________________ Name 1) (10 -points) a) (2.5) Is there evidence for a genetic basis for HIV resistance? Yes b) (2.5) If so, how is the resistance allele of the gene behaving? (ie dominant, recessive, etc.) Semi-dominant (incomplete dominance), as the heterozygous individuals show partial phenotype. c) (2.5) Is there evidence that the gene is X-linked? Explain your answer. No - family 1 excludes this possibility, as the boys could not be carriers in this scenario. d) (2.5) Despite their genotypes, none of the children in families I, II, III or IV become HIV positive. Why? Environmental factors, in this case lifestyle choices, determine whether susceptibility translates into actual infection.
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EXAM 1, BIOSCI 20192, 2010 ___________________________ Name 2) (20 points) DNA is extracted from the cells of each individual, and microsatellite markers located throughout the genome are used to genotype the DNA. The results for three such markers are shown below the pedigree. a) (5) Is there evidence for linkage with any of the three markers shown? If so, which marker? Linkage to Marker 2 is possible b) (5) If you predict linkage, what allele of this marker appears to be linked with the resistance allele of the gene of interest? If RR is resistance and Rr is semi-resistance: The 2 allele of marker #2 seems to
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This note was uploaded on 02/09/2011 for the course BIOS 20182 taught by Professor Lahn during the Spring '11 term at UChicago.

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2010 exam with answers - EXAM 1, BIOSCI 20192, 2010 _ Name...

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