2005 Final examination of Medical Genetics.doc

2007 Final examination of Medical GeneticsName_ student number_1. Explain the following terms.1) Genomic imprinting2) Mosaicism3) Nondisjunction4) Isochromosome5) pleiotrophy6) RFLP7) ASO8) the central dogma2. Choose a correct answer from A,B,C,D or E.(40 scores)1) This stuructrure emanates from the centromere and contacts the spindle fibers during mitosis: a) alpha statellite b) subtelomerec) euchromatind) kinetochore2) The notable feature of Down syndrome is:a) the incidence of infants is associated with mothers ageb) fathers age has influence on the infants incidencec) younger mother has a much higher riskd) the risk due to translocation is related to maternal age3) The following description about etiology of Trisomy 21,which is right:a) The older egg model is one obvious possibilityb) The nondisjunction of chromosome 21 is not established by recombination machinery. c) Younger eggs may be less able to overcome the susceptibility to nondisjunctiond) etiology event may not have been put in place 35 to 40 years ago 4) about inversion, which of the following is righta) a paracentric inversion carrier can lead to the production of liveborn child with unbalanced karyotypeb) a pericentric inversion carrier can lead to the production of liveborn child with unbalanced karyotypec) pericentric inversion is easier to identify than paracentric inversiond) the phenotype of a carrier of inversion is abnormal5) about reciprocal translocation, which of the following is wronga) Total chromosome number in a karyotype remains 46b) A carrier of such translocation has an increased risk of producing unbalanced gametesc) A configuration will be formed when chromosomes pair during meiosisd) Adjacent-1 is the usual way when chromosomes segregate in anaphase from configuration6) About mosaicism, which of the following is righta) Mosaicism for sex chromosome abnormalities is relatively more common than for autosomal abnormaltiesb) Mosaicism may be only numericalc) The effects of trisomy mosaicism on development depend on the timing of nondisjuction eventd) Phenotypes of mosaicism are usually sever 7) The following description about duplication, the right is:a) can originate by equal crossing over b) is usually more harmful than deletionc) usually physically normal d) can originate by abnormal segregation from meiosis8) The following description about numerical abnormalities, the right is:a) Euploid and aneuploid together are called heteroploidb) Triploid can result from endomitiosisc) Tetraploid can result from dispermyd) Euploidy is the most common type of human chromosome disorder9) The following symptoms should not be performed cytogenetic analysis:a) Problems of early growth and developmentb) Stillbirth and neonatal death c) Fertility problemsd) Pregnancy of woman younger than the age of 30 years 10) Which of the following can not escape X inactivationa) Genes are located on pseudoautosomal region b) Genes which have related copies on Y chromosomec) genes on the middle of long arm of X chromosomed) genes on the terminal end of short arm of X11) Which of the following events occurs during a synapsis?a) randomly separating the maternal and paternal chromosomes b) replication of the DNA c) mixing half the maternal chromosomes with half the paternal chromosomes d) pairing of homologues12) The moving apart of each pair of homologous chromosomes during anaphase I of meiosis is called a) duplication b) crossing over c) disjunction d) replication 13) Although sperm and egg are both produced by the process of meiosis, they differa) from a genetic point of view. each gene stands an equal chance of ending up in a sperm but has a 50% chance of being discarded in the polar body in egg production. b) in the allocation of cellular food supply. c) in mortality. d) All of these above are correct.14) Another name for a tetrad is a(n)a) homologue b) bivalent c) oocyte d) gamete15) What region of deletion causes Cri du chat syndrome?a) 5p12b) 5p13c) 5p14d) 5p1516) An inactivated X chromosome in the nucleus of a cell appears as a _ in the microscope.a) normal X chromosomeb) polyploidc) Barr bodyd) monosomy17) If non-disjunction occurs in the first meiotic division of a male gonadal stem cell for chromosome #21:a) one would expect an equal number of normal and aneuploid gametes.b) more disomic than nullisomic gametesc) an equal number of nullisomic and disomic gametesd) a ratio of normal, disomic and nullisomic gametes of 2:1:118) A nineteen year old female with short stature, wide spaced nipples, and primary amenorrhea most likely has the karyotype of:a) 47,XX,+18b) 46,XYc) 47,XXYd) 45,X19) Which of the following procedures are used for detection of specific DNA sequences in interphase nuclei or chromosomes?a) C-bandingb) fluorescence in situ hybridization (FISH)c) G-bandingd) Q-banding20) Which of the following syndromes are associated with maternal disomy for chromosome 15?a) Hydatidiform moleb) Prader Willi Syndromec) Angelman Syndromed) Turner syndrome21) A mutation changes a CG base pair to an AT base pair. This is a _ mutation.a) transversionb) Transitionc) transpositionald) ltranslocation22) A DNA nucleotide may consist ofa) a ribose sugar, a phosphate group, and adenine.b) a phosphate group, deoxyribose, and cytosinec) uracil, deoxyribose, and a phosphate group. d) deoxyribose, thymine, and a hydroxyl group.23) Which is the most accurate representation of the organization levels of the genetic information in cells?A. genes nucleotide chromosomes genomeB. genome genes nucleotides chromosomesC. chromosomes genes nucleotides genomeD. nucleotides genes chromosomes genome24) A codon specifies a(n)A. amino acid.B. nucleotide base pair.C. protein.D. enzyme.25) Most eukaryotes areA. haploid.B. diploid.C. polyploid.D. aneuploid.26) Which is found in RNA, but not DNA?a) phosphateb) adeninec) ribosed) cytosine27) The two polynucleotide chains in a molecule of DNA are held together by what type of bond?a) phosphodiesterb) phosphatec) peptided) hydrogen28) Which of the following is a DNA base pair?a) A-Tb) T-Cc) A-Ud) G-T29) Which disease is caused by a mutation in a gene located on the X chromosome?a) PKUb) Albinismc) Lesch-Nyhan syndromed) Tay-Sachs disease30) The most severe form of Lesch-Nyhan syndrome affectsa) males only.b) females only.c) more males than females.d) more females than males.31) The DNA sequence of a gene is 3C C A T G C T A-5 The corresponding sequence of the mRNA produced from this gene isa) 5 -C C A T G C T A- 3b) 3G G T A C G A T- 5c) 3A T C G T A C C-5d) 5G G U A C G A U-332) Before any kind of post-translational processing occurs, all polypeptides begin with the amino acida) leucine.b) glycine.c) methionine.d) tyrosine.33) In the genetic code, the codon UAG signifies which amino acid?a) methionineb) leucinec) glycined) none of these34) A plasmid is treated with the restriction enzyme PstI. To facilitate cloning a fragment of DNA from a bacterial chromosome into this plasmid, the chromosomal DNA should be treated witha) PstIb) PstIIc) PstIIId) any of these enzymes would work35) A best vector in which to clone a 1.2 kb fragment of DNA is aa) plasmid.b) bacteriophage.c) cosmid.d) YAC.36) Which of the following is an example of a nonsense mutation?a) ACG to ACC b) AUG to UUG c) UAC to UAGd) AA to UUU37) A restriction endonucleasea) makes a DNA copy of a molecule of RNA.b) cleaves DNA at specific nucleotide sequences.c) produces an mRNA transcript from the DNA of a gene.d) joins DNA fragments during cloning.38) A cDNA library represents all of the _ in a cell.a) genesb) DNAc) RNAd) mature mRNAs39) The northern blot technique is used in the analysis ofa) DNA.b) cDNA.c) mRNA.