BISC403 Exam 2, 3-22-12
1. Suppose an individual is heterozygous for a pair of alleles (e.g., A/a). Under what conditions would a double crossover in a somatic cell of this individual lead to a clone of cells homozygous for a?
Ans: B 2. A) B) C) D) E) The nicking of DNA that initiates recombination during mitosis may be due to all but instruction from normal cell-cycle program. X-rays. chemical damage. physical damage. radiation. Ans: A
3. If 35% of the bases in a region of the mouse genome are cytosine, what percentage in that region are adenine? A) 15% B) 20% C) 30% D) 35% E) none of the above Ans: A 4. A) B) C) D) E) DNA is localized mainly in the: cell membrane. endoplasmic reticulum. vacuoles. chromosomes. none of the above Ans: D
BISC403 Exam 2, 3-22-12 5. A) B) C) D) E) 6. A) B) C) D) E) 7. A) B) C) D) E) 8. A) B) C) D) E) In mammalian cells, replication proceeds: unidirectionally bidirectionally unidirectionally from many origins. bidirectionally from only one origin. both unidirectionally and bidirectionally depending on the origin Ans: B DNA replication occurs through a _________process. conservative semiconservative dispersive transferal none of the above Ans: B The group of enzymes able to relax supercoils in DNA is called: primases. helicases. topoisomerases. telomeres. ligases. Ans: C During early interphase the state of the DNA can be described as: a single continuous linear double helix. a double helix replicated semiconservatively. a double helix replicated conservatively. single-stranded DNA. none of the above Ans: A
9. Which of the following is not involved in ensuring the accuracy of a cell's genetic information? A) redundancy B) repair enzymes C) precision of replication machinery D) DNA polymerase proofreading mechanism E) recombination Ans: E
BISC403 Exam 2, 3-22-12 10. Two strains of S. cerevisae (yeast) are crossed. One has the genotype ABC and the other abc. Five sets of the resultant tetrads are noted below. In which set did a gene conversion event occur? A) abc, aBc, AbC, aBC B) abc, abc, ABC, ABC C) aBc, aBc, AbC, AbC D) abC, abc, ABc, ABC E) Abc, Abc, aBC, aBC Ans: A 11. Without __________ regions on the DNA during recombination, gene conversion could not occur. A) homoduplex B) heteroduplex C) homotriplex D) heterotriplex E) none of the above Ans: B 12. A) B) C) D) E) Replacing a thymine nucleotide with a guanine is an example of a: translocation. transition. transversion. forward mutation. reversion or reverse mutation. Ans: C
13. Assume that the wild type sequence is 5’-GGCCTAC-3’. After treatment with the base analog 5-Bromouracil that initially base pairs with adenine, but then can adopt a rare state to pair with guanine. Indicate the sequence that would be produced by this treatment. A) 5’-GGCCGAC-3’. B) 5’-GGCCTTC-3’. C) 5’-GGCCAAC-3’. D) 5’-GGCCTGC-3’. E) No changes in the sequence would occur Ans: D
BISC403 Exam 2, 3-22-12 14. Considering the mechanism required to generate the mutant sequence above, what is the fewest generations required to mutate this sequence? A) one generation B) two generations C) three generations D) four generations E) it will not occur Ans: C 15. The bacterial repair system that corrects mismatched bases after polymerization is able to discriminate between the old and newly made DNA strands because: A) the new strand will contain the incorrect base if a mismatch occurs. B) older DNA is more likely to...