Molecular Genetics Final exam page 1 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________ ------------------------------------------------------------------------------------------------------------- Define each of the following terms, explaining what it is and how it is used for molecular genetics research in one or more of the genetic model organisms we discussed (5 points each): recombinant inbred lines Balancer chromosomes ES cellsMolecular Genetics Final exam page 2 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________ ------------------------------------------------------------------------------------------------------------- The cre site-specific recombinase T-DNA GAL4 (in this case, explain how it is used in model organisms other than S. cerevisiae)Molecular Genetics Final exam page 3 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________ ------------------------------------------------------------------------------------------------------------- 1. (6 points) At a given locus, three alleles, 1, 2 and 3 are present in a population in Hardy-Weinberg equilibrium and no other alleles are present at appreciable frequencies. Homozygotes for allele 1 represent 25% of the population. Do you know what fraction of the population is heterozygous for allele 1? If so, what is that fraction? 2. (4 points) Building on question 1, heterozygotes between alleles 1 and 2 represent 20% of the population. What fraction of the population is homozygous for allele 2? 3. (4 points) Building on questions 1 and 2, what fraction of the population is homozygous for allele 3? 4. (4 points) You isolate DNA from a haploid strain of yeast and from a closely related and highly inbred diploid strain. In separate reactions of the same volume you allow 100 micrograms of DNA from each strain to denature and hybridize. a) DNA from the haploid strain would hybridze faster by a factor of 4 b) DNA from the haploid strain would hybridze faster by a factor of 2 c) DNA from the two strains would hybridize at the same rate d) DNA from the diploid strain would hybridze faster by a factor of 2 e) DNA from the diploid strain would hybridze faster by a factor of 4 5. (4 points) You repeat this experiment using DNA from the same number of cells rather than the same mass of DNA. This time a) DNA from the haploid strain would hybridze faster by a factor of 4 b) DNA from the haploid strain would hybridze faster by a factor of 2 c) DNA from the two strains would hybridize at the same rate d) DNA from the diploid strain would hybridze faster by a factor of 2 e) DNA from the diploid strain would hybridze faster by a factor of 4Molecular Genetics Final exam page 4 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________ ------------------------------------------------------------------------------------------------------------- You are studying a new mutation in the yeast Saccharomyces cerevisiae that is uv sensitive (no growth when irradiated 30 Jm–2 of ultraviolet light). You have named your mutation mrd2, for my radiation sensitive 2 (although you anticipate re-naming it if it turns out to be allelic to an existing RAD gene). It may be a new gene, and you want to investigate. First, you cross your haploid mrd2 strain to a haploid strain of the opposite mating type carrying can1 and cup5, both recessive markers on chromosome V. The phenotype of can1 is resistance to canavanine. The phenotype of cup5 is sensitivity to copper. CAN1 lies at position -50 cM (50 cM to the left of the centromere) and CUP5 lies at -18 cM (32 map units to the right of CAN1, so the expected recombination frequency between can1 and cup5 is about 23.6%). The resulting mrd2/MRD2; can1 cup5 / CAN1 CUP5 diploids are wild-type (they grow after exposure to 30 Jm–2 of ultraviolet light) and sporulate normally. You induce sporulation and examine the haploid spores. 6. Among the resulting haploid spores 50% are cup5. (5 points) What fraction of the cup5 haploids are also resistant to canavanine? You identify 20 colonies that are can1 CUP5 using plates with canavanine and copper. 7. (5 points) If MRD2 is unlinked (not on chromosome V), what fraction of these 20 colonies do you expect to continue growing after exposure to 30 Jm–2 of ultraviolet light? 8. (6 points) In this case (MRD2 is unlinked) could you determine whether it is near the centromere of the chromosome that it is on? Is so, how would you do that? 9. (5 points) If MRD2 is at -52 cM., 2 cM. to the left of CAN1, what fraction of these 20 colonies do you expect to continue growing after exposure to 30 Jm–2 of ultraviolet light? 10. (5 points) If MFT2 lies at -34 cM. (precisely between CAN1 and CUP5) what fraction of these 20 colonies do you expect to continue growing after exposure to 30 Jm–2 of uv light? 11. (5 points) If MFT2 lies at -16, 2 cM. to the right of CUP5, what fraction of these 20 colonies do you expect to continue growing after exposure to 30 Jm–2 of ultraviolet light?Molecular Genetics Final exam page 5 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________ ------------------------------------------------------------------------------------------------------------- For each of the following types of inheritance indicate which progeny are at risk (circle the letter corresponding to all that apply). Assume that the trait is very rare (intermarrying partners are not affected and are not carriers). 12. (4 points) In the case of an autosomal dominant trait a) 1 b) 2 c) 3 d) 4 13. (4 points) In the case of a maternally imprinted trait a) 1 b) 2 c) 3 d) 4 14. (4 points) In the case of a paternally imprinted trait a) 1 b) 2 c) 3 d) 4 15. (4 points) In the case of a recessive sex-linked trait a) 1 b) 2 c) 3 d) 4 16. (4 points) In the case of a trait conferred by a mitochondrial gene a) 1 b) 2 c) 3 d) 4 17. (4 points) In the case of a Y-linked trait a) 1 b) 2 c) 3 d) 4Molecular Genetics Final exam page 6 of 8 BSCI410 Monday, Dec. 15, 2008 Your name: _____________________________________________________________