遗传学试题资料：期中测试

1、1. Wich of the following best explains variable expression in mitochondrial diseases?(2.0分)A.locus heterogeneityB.heterozygosityC.heteroplasmyD.modifierlociE.imprinting2. Some autosomal recessive diseases have a highprevalence in large populations, even though they are often fatal (e.g., sicklecell

2、disease in Africans, cystic fibrosis in Europeans). Which of the followingis the most likely explanation for this phenomeno(2.0分)A.InbreedingB.Highmutation rates in specific populationsC.Survivaladvantage in heterozygous carriersD.Survivaladvantage in individuals who are normal homozygotesE.Noneof t

3、he above mechanisms explain the pattern3. You would be likely to observe the lowest heritability score in(2.0分)A.Cystic fibrosis 囊性纤维化ARB.Spinabifida 脊柱裂C.Cleft lip/palate 唇裂腭裂 1.4/1000D.Mumps 腮腺炎E.Congenitalheart disease 先天性心脏病4. Which of the following would you not expect to see in a typical multi

4、factorial disorder?(2.0分)A.Positive correlation between prevalence of the disorder in the population and sibling recurrence risk 正相关B.Rapid decrease of recurrence risk with more remote degrees of relationshipC.Co-occurrence of the disorder in fathers and sonsD.Sibling recurrence risk of 50%E.Higher

5、concordance in monozygotic twins than in dizygotic twins5. Which of the following diseases is a good example of locus heterogeneity?(2.0分)A.Prader-Willisyndrome 第15号染色体缺失B.MyotonicdystrophyC.Osteogenesis imperfecta 成骨发育不全ADD.Duchenne muscular dystrophy DMDE.HemophiliaA 血友病6. Mutations in fibrillin g

6、ene can cause(2.0分) P80A.RetinoblastomaB.AchondroplasiaC.Neurofibromatosistype 1D.HuntingtondiseaseE.Marfansyndrome7. Bob has hypophosphatemic rickets（低磷酸盐血症）. He and his wife Jill come to the genetics for counseling because they would like to have children. What can you tell them about the likeliho

7、od that any daughters will be affected? Anysons?(2.0分)A.50%daughters, 100% sonsB.100%daughters, 50% sonsC.0%daughters, 100% sonsD.100%daughters, 0% sons8. Your patient is a 5-year-old girl who appears to have Duchenne muscular dystrophy. What is the most likely genetic explanation for this disease i

8、n a girl?(2.0分)A.She has a 46, XY karyotype with sex reversal.B.She has skewed（偏离的；倾斜的）X inactivation.C.She has two independent DMD mutations.D.She has a dominant negative mutation.E.This diagnosis is impossible.9. Which of the following properties would a single nucleotide polymorphism (SNP) have t

9、o be detected by Southern blot（DNA印记）?(2.0分)A.It must alter the encoded amino acid sequenceB.It must alter a splice siteC.It must alter a restriction siteD.It must be a nonsense mutationE.It must alter the stability of the encoded mRNA10. Which of the following could produce an XY female?(2.0分)A.Poi

10、ntmutation in the Sry geneB.Deletionof the Sry geneC.Translocationof the Sry gene to the X chromosome during meiosis in the fatherD.All of the above11. Which of the following statements is incorrect regarding the recurrence risk of multifactorial inherited disorders(2.0分)A.The risk gets higher when

11、the degree of relationship increasesB.The risk gets higher when the number of patients in the family increaseC.The risk for their children gets higher when the patients are seriously affectedD.The risk gets higher when one or both parents are affected12. A man who is affected with hemophilia A (X-li

12、nkedrecessive) mates with a woman who is a heterozygous carrier of this disorder.What proportion of this couples daughters will be affected?(2.0分)A.0.25B.0.5C.0.75D.113. The correct number of 46 human chromosomes was discovered by(2.0分)A.MendelB.MorganC.Tjio and LevanD.CasperssonE.Watson14. Differen

13、ces between male and female meiosis include:(2.0分)A.4 vs. 1 gametes generated per meiosisB.Female meiosis begins prenatally but arrests in dictyotene until each menstrual cycleC.Meiosisin females requires fertilization for completionD.All of the aboveE.None of the above15. Relative to nuclear DNA, t

14、he mutation rate of midochondrial DNA is:, XX/45, X表明为：(2.0分)A.Apparently lower, due to the number of copies of mtDNA per cellB.Approximately equalC.Higher, due to limitations in DNA repair capabilitiesD.Lower,due to protection of the mitochondria from environmental insults16. Coding strand(2.5分)In

15、double-stranded DNA, the strand that has the same 5to3 sense as mRNA. The coding strand is the strand that is not transcribed by RNA polymerase. 17. Gene pool(2.5分)The genetic constitution of a population of a given organism.18. SNP(2.5分)A polymorphism in DNA sequence consisting of variation in a si

16、ngle base.19. HapMap(2.5分)A set of haplotypes, defined by tag SNPs, distributed throughout the genome, used for association studies.20.同义突变和无义突变(5.0分)Silent mutation: changes in DNA which do not affect protein expression or function.Nonsense mutation: A single-base substitution in DNA resulting in a

17、 chain-termination codon.21.常染色体和常染色质(5.0分)Autosome: Any nuclear chromosome other than the sex chromosomes;22pairs in the human karyotype.Euchromatin: slightly and evenly stained, non or low repetitive DNA regions.22.单倍体和单倍型(5.0分)Haploid: The chromosome number of a normal gamete, with only one membe

18、r of each chromosome pair. Haplotype : A group of alleles in coupling at closely iinked loci, usually inherited as a unit.23.基因组和基因库(5.0分)Genome Total genetic information in a living organism.Gene pool The genetic constitution of a population of a given organism.24. You are asked to see a child with

19、 hereditary tyrosinemia, an autosomal recessive disorder of amino acid metabolism that causes liver failure. Both parents are of French Canadian ancestry, and come from a region of Quebec where 1:1600 newborns are affected with tyrosinemia. What is the carrier frequency of tyrosinemia in this region

20、? You learn that 90% of mutations responsible for tyrosinemia in this population consist of the same single base change. This mutation is much less common elsewhere in the world. What is most likely to account for the high frequency of this mutation in as mall region in Quebec?(10.0分)25.carrier frequency 1/20 The high frequency is because of the founder effect. Their ancestor were the carrier. And for the lack of gene exchanging, the frequency becomes higher than normal level.What is the paren