genetics04 - UNIVERSITY OF TORONTO Faculty of Arts and...

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Unformatted text preview: UNIVERSITY OF TORONTO Faculty of Arts and Science APRIL/MAY EXAMINATIONS 2004 HM8265H1 S Duration — 3 hours No aids allowed (Non-programmable calculators are permitted) Note: Please hand in this exam booklet and the scantron sheet to the invigilators at the end of the exam. Name: Student Number: 1. Genes on the X chromosome of mammals and Drosophila are particularly suitable for genetic study because: 3) males have only one X and most genes behave as haploids. b) females have only one X and most genes behave as haploids. c) the X chromosome is large and many more genes are located there. d) when present as Barr bodies they are exposed for electron microscopic examination. e) they behave as diploids in females. 2. Shown below are the deletion maps of a series of mutations. The deleted region is indicated as ( .... ..) and the intact region as . Note that strain 5 carries two different deletions. 1 ( ......... ..) 2 ( ......... ..) 3 ( ................... ..) 4 ( .............. ..) 5 ( ........ ..) ( ....... ..) A series of point mutations A—E is used in a mating experiment. Shown below are the results of those crosses. Ability to produce wild-type progeny is indicated by (+), (0) indicates no wild type progeny. 1 2 3 4 5 A + + o + o ‘ B + o + + + C + + o + + D o + + + + E + + + o 0 indicate the order that is most consistent with these data. a) CADBE b) DEBAC c) BADCE d) ABDEC e) CEADB 3. Assume 8 different strains of fly have been isolated; each shows a recessive white-eye trait. Crosses are performed as follows; (w) indicates white-eyed progeny, (R) indicates wild-type red eyes. A B C D E w w R R W w R R w w w R w R w mommUowb awwwwww sswwwwwo swwawwsam Based on these crosses, how many different genes are present and what strains have mutations in the same gene as does strain A? a) 2, B, E, and H b) 3, B and C c) 3, B, C, and H d) 3, B, E, and H e) 4, B and H 4. A neomorphic mutation results in an allele that: a) produces no gene product. b) produces a nonfunctional gene product. c) produces novel proteins or cause inappropriate expression resulting in a new phenotype. d) produces proteins that aggregate with wild—type subunits, inactivating them. e) produces an altered protein that results in a wild-type phenotype. 5. A transgene vector designed to be specifically nonfunctional when it replaces the normal homologous gene by homologous recombination is called a: a) deletion mutant. b) frameshift mutant. 0) promoter-less reporter gene construct. d) expression construct. e) “knock out” construct. 6. STSs are: a) microsatellite sequences. b) generally highly polymorphic. 0) unique markers along the chromosome. d) a and b e) b and c 7. A contig is: a) a map of genetic markers that separated by less than 1cM. b) a map showing the order of cloned bits of DNA. c) unique DNA sequences that serve as molecular markers. d) sets of two or more partially overlapping cloned DNA fragments. e) the nucleotide sequence of an entire chromosome 8. The highest resolution analysis of a genome can best be generated from: a) haplotype mapping b) linkage mapping c) sequence analysis d) FlSH e) radiation hybrid mapping 9. What DNA sequence information is not present in a cDNA? a) the promoter b) the introns c) the axons d) the 3' untranslated region e) a and b 10. If a PCR amplified sample hybridizes with two allele specific probes, one normal and one mutant sequence, a carrier is identified if: a) both probes give a signal. b) neither probe gives a signal. c) only the mutant probe gives a signal. d) only the non-mutant probe gives a signal. 9) none of the above 11. Molecular geneticists equate an allele with: a) only transcribed genes. b) only non-transcribed DNA. c) any DNA site that is different among genomes. d) any DNA site that is different among coding genomes. e) any DNA site that is different among non-coding genomes. 12. Which is the most frequent cause of DNA polymorphism? a) single base differences b) duplications c) inversions d) transiocations e) ploidy 13. Positional cloning requires: a) knowledge about the function of a gene. b) knowledge about the expression pattern of a gene. 0) knowledge about the map location of a gene. d) knowledge about the sequence of a gene. e) knowledge about amino acid sequence of the encoded protein. 14. If a gene is thought to be a possible disease gene, one can: a) sequence alleles from affected and unaffected family members. b) examine the expression pattern of the gene. c) make a transgenic mouse, if an appropriate mouse mutation is known. d) all of the above e) a and c 15. Alterations in gene expression patterns can be studied using: a) cDNA microarrays b) oligonucleotide microarrays c) northern blots d) Maldi—Tof mass spectrometer e) all of the above 16. Deletions, and duplications are most often caused by: a) ultraviolet light. b) ionizing radiation. c) unequal crossing over. d) all of the above. e) b and c only 17. In general, which of the following usually has a greater chance of lethality than the others? a) inversion b) duplication c) deletion d) translocation e) all have an equal chance 18. An inversion may result from: a) a half-circle rotation of a chromosomal region following two double-strand breaks in a chromosome's DNA. b) the action of a transposable element. 0) a crossover between DNA sequences present in two positions on the same chromosome in inverted orientation. d) all of the above e) none of the above 19. Acentric fragments are produced in: a) paracentric inversions b) pericentric inversions c) translocations d) deletions e) duplications 20. A meiocyte of an organism heterozygous for a reciprocal translocation goes through meiosis and results in 4 viable meiotic products. This means: a) the translocation reverted b) a suppressor mutation occurred 0) there was adjacent segregation d) there was alternate segregation e) translocation breaks were very close to the centromere 21. Which of the following sex chromosome aneuploidies is not usually seen in live births? a) XO b) XXY 0) YO d) XXX e) None of the above 22. During mitosis, if the chromosomes in a diploid tissue fail to separate after replication, the resulting daughter cells will be: a) monoploid. b) tetrasomic. c) triploid. d) tetraploid. e) haploid 23. In corn, R is a gene for red aleurone; its recessive allele rdetermines colourless aleurone. A cross Was made between a diploid r/r female and a trisomic R/r/r male. lf pollen grains with extra chromosomes are inviable, the ratio of red to colourless kernels expected in the progeny is: a) 1 red : 5 colourless b) 1 red : 2 colourless c) 1 red : 1 colourless d) 2 red : 1 colourless e) 5 red : 1 colourless 24. When an allotetraploid is backcrossed to one of its progenitor species, a sterile progeny is produced. This sterile individual can be best represented by: a) 111 + n; b) 2H1 + 2H2 0) 2m d) 2’12 e) 2m + 112 25. A triploid with 5 chromosomes in each set (3n = 15) is discovered. What is the probability of a meiosis in which all univalents pass to the same pole? a) 1/5 b) we c)1/15 d) 1/16 e) 1/25 26. Many, but not all, DNase hypersensitive (DH) sites are found: a) at the 5‘ ends of genes to be transcribed by the cell. b) in and near nucleosomes. 0) near histone-rich regions. d) in regions of heterochromatin e) all of the above 27. Mutations altering the amount of protein synthesized from a reporter construct occur most often in which of the following sequences of DNA? a) The reporter gene. b) Cis—acting DNA elements. c) X—gal coding sequence. d) RNA polymerase II gene. e) none of the above 28. The promoter of nearly all eukaryotic genes contains a(n): a) RNA polymerase binding region. b) TATA box. c) initiation site. d) b and c only e) a, b and c 29. Which of the following is not true of enhancer DNA sequences? a) They contain the TATA box regulatory element. b) They retain function if their nucleotide sequence is inverted. 0) They can be more than 10 kilobases from the gene they regulate. d) They may increase or decrease gene transcription levels. e) They may contain multiple regulatory elements. 30. The primary function of basal transcription factors is to: a) repress transcription initiation of a particular gene. b) assist in associating RNA polymerase with the promoter element. c) increase transcription by binding enhancer sequences. d) activate RNA synthesis at origins of replication. e) regulate activity of DNA polymerase II. 31. Mutations in the GAL80 gene in yeast result in the continuous expression of the GAL1, GAL7, and GAL10 genes, even in the absence of galactose. This genetic evidence suggests that the GAL80 gene product acts as a(n): a) transcriptional repressor. b) promoter element. 0) enhancer element. d) transcriptional activator. e) RNA polymerase. 32. The association of DNA with histones to form chromatin affects transcription by: a) increasing basal transcription rates. b) decreasing basal transcription rates. c) increasing transcription of a few genes, while not influencing most others. d) decreasing transcription of a few genes, while not influencing most others. e) increasing transcription of some genes and decreasing transcription of others. 33. Hypercondensation of heterochromatin results in: a) hyperactivation of transcription. b) suppression of progression through metaphase. c) DNA replication. d) transcriptional silencing. e) none of the above 34. is used to describe a situation in which a gene's expression pattern is dependent upon the parent from which it was inherited. a) Genomic imprinting b) Spermatogenesis c) Heterodimerization d) Homodimerization e) Gender-specific RNA stability 35. Loss of the poly-A tail associated with eukaryotic mRNAs results in: a) rapid translation of the transcript. b) elongation of the transcript. c) decreased translation initiation on the transcript. d) rapid degradation of the transcript. e) the addition of a new polyA sequence to the transcript. 36. Which Fragile-X allele is most likely to expand when maternally transmitted? a) (CGG)20 b) (CGG)ss c) (CGG)5o (AGG)1 (CGG)50 d) (066)101 e) Fragile-X premutations tend to contract when maternally transmitted {6 .6“ «s (.0 9 37. How does the cystic fibrosis gene mutation AF508 (the major mutation in Northern Europe) affect the encoded CFTR protein? a) It leads to decreased CFTR expression through destabilization of the transcript b) It results in mislocalisation of CFT R to the nuclear membrane c) It leads to decreased affinity for chloride ions and decreased CFTR conductance d) It results in CFTR that is blocked for processing and rapidly degraded e) It leads to CFTR protein that is unable to hydrolyze ATP 38. Recessive caffeine hypersensitivity syndrome has been linked to mutations in either of two genes, Espressoin and Cappuccinoin. The proteins encoded by these genes have been found to function sequentially (as written above) in a cellular pathway that repairs DNA damage caused by caffeine. Not surprisingly, cell lines derived from these patients die when exposed to caffeine in tissue culture. Which of the following statement(s) is true? a) Introduction of a functional Espressoin gene into Espressoin -/- cells will correct the caffeine hypersensitivity b) Introduction of a functional Espressoin gene into Cappuccinoin -/- cells will correct the caffeine hypersensitivity c) Fusion of cells derived from an Espressoin -/- patient to those derived from a Cappuccinoin -/- patient will result in normal (corrected) caffeine sensitivity d) Fusion of cells derived from an Espressoin —/- patient to those derived from another Espressoin -/- patient will result in normal (corrected) caffeine sensitivity e) Both a & c f) Both a & d 39. Which of the following statements regarding the XPD gene is false? a) Different mutations in the XPD gene have been found in patients with Cockayne syndrome, Xeroderma pigmentosum, and Trichothiodystrophy b) XPD protein functions in both basal transcription and nucleotide excision repair c) Xeroderma pigmentosum associated with XPD mutations is caused by a defect in the basal transcription-associated function of the XPD protein d) Cells derived from patients with XPD mutations will complement the UV- sensitivity of cells with mutations in XPB in cell fusions e) Some XPD gene mutations result in temperature-sensitive impairment of the encoded protein ...
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genetics04 - UNIVERSITY OF TORONTO Faculty of Arts and...

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