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1. ？Panacin is a hypothetical drug that you are testing in a large population. You find a continuous dose-response curve in the population. If youre interested in studying genetic variation that contributes to panacin response, what does this suggest to you?(9.0分)A.There are likely to be multiple genes involved in the response to panacin. B.The number of genes involved equals the number of peaks in the dose-response curve.C.There is a threshold of response controlled by a major gene. D.One gene has a major effect on the response to panacin. E.There are likely to be multiple genes involved in the response to panacin. 2. Wich of the following best explains variable expression in mitochondrial diseases?(9.0分)A.modifier lociB.heterozygosityC.heteroplasmyD.locus heterogeneityE.imprinting3. Marsha is heteroplasmic for a MELAS mutation. What feature of oogenesis most strongly influences the level of mtDNA mutation she will pass to her children, which would influence the clinical expression of disease?(9.0分)A.Energy requirements in the oocyte that influence natural selection for mtDNA mutationsB.The long time that elapses between the beginning and the end of oogenesisC.The mitochondrial genetic bottleneckD.The small number of mitotic divisions during oogenesisE.The low fitness of mtDNA mutations in the oocyte4. Some tissues are affected by mitochondrial mutations more severely than others. One would expect these tissues would have a high requirement for which of the following?A. BloodflowB.Macromolecular transport C.Metabolic energyD.ProteinE.Free radicals5. Relative to nuclear DNA, the mutation rate of midochondrial DNA is:(9.0分)A. Higher, due to limitations in DNA repair capabilitiesB.Apparently lower, due to the number of copies of mtDNA per cellC.Approximately equalD. Lower, due to protection of the mitochondria from environmental insults6. Sara has mitochondrial encephalomyopathy and stroke-like episodes (MELAS). Her genetic counselor tells her that it is very difficult to predict the severity of the syndrome in any affected children that she will have. What property of mitochondrial mutations, which is distinct from nuclear mutations, explains this variability in the expression of mitochondrial mutations?(9.0分)A.epistasisB.incomplete dominanceC.pleiotropyD.mutation heteroplasmyE.the lack of DNA repair enzymes in mitochondria7. A child is hospitalized with anemia, jaundice, and cholelithiasis. The lab reveals hemolysis and sickle cell anemia, which occurs at a frequency of 1 in 500 individuals. Which of the following represents the frequency of sickle cell carriers in the same population?(9.0分)A.0.5B.0.045C.0.086D.0.002E.0.9558. If the incidence of cystic fibrosis in the white population in approximately 1 in 4000, what is the carrier frequency?(9.0分)A.1/100B.1/32C.1/64D. 1/20E.1/2009. Disregarding the effects of selection, if one in every 400 people in a population has sickle cell disease, what is the carrier frequency for the disease mutation?(9.0分)A.1 in 200B.1 in 20C.1 in 40D.1 in 10E.1 in 160010. Some autosomal recessive diseases have a high prevalence in large populations, even though they are often fatal (e.g., sickle cell disease in Africans, cystic fibrosis in Europeans). Which of the following is the most likely explanation for this phenomenon?(9.0分)A.Survival advantage in individuals who are normal homozygotesB.High mutation rates in specific populationsC.Survival advantage in heterozygous carriersD.InbreedingE.None of the above mechanisms explain the pattern11. A 19-year-old patient complains of a loss of central vision in both eyes. The onset was less than 6 months ago and has progressed rapidly. The pedigree you construct of the probands family reveals vision loss in the patients mother, all her five siblings, and the probands maternal grandmother. You develop a differential diagnosis of likely disorders that includes which of the following? (10.0分)A. Kearns-Sayre syndrome -听力B. MELAS syndrome -耳聋C. Leber hereditary optic neuropathy -视力 D. Retinoblastoma E. Leigh syndrome
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