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Unformatted text preview: Microbial Genetics BIOL518 Exam 2 - Fall 2010 Name_____________________________________________________________________ Multiple Choice. Choos e all of the correct answers for each question. There may be more than one correct answer per question. (44 points, 4 pts each) 1: In DNA repair mediated by the UvrABC endonuclease, the UvrBC complex : A: recognizes slight distortions in DNA due to damage. B: determines which DNA strand is methylated. C: nicks the damaged DNA strands 7 nt 5' and 4 nt 3' of the damage. D: directly cleaves T-T dimers. 2: The process of Photoreactivation Repair: A: requires the addition of energy in the form of ATP to repair the DNA damage. B: involves the enzyme Photolyase. C: excises the two T's involved in a TT-dimer, and then DNA Pol I places new nucleotides at those positions and DNA ligase seals the nick. D: can identify the DNA strand that needs to be repaired by the absence of methyl groups. 3: If each of the below mutations were to occur near the beginning of a gene, which would have relatively high expectations to still express a functional protein? A: Deletion of 2 base pairs B: Missense mutation C: Nonsense mutation D: Frameshift mutation 4: The roles of the Rep protein in the mechanism of Rolling Circle DNA replication include the following: A: Forms a homodimer and introduces a nick in the single stranded origin of the plasmid B: Becomes covalently attached to the 3' end of the nicked strand of the plasmid C: Cuts at the double stranded origin following one round of replication to release the displaced ssDNA from the newly synthesized DNA strand. D: Rep joins the ends of the displaced strand with each other to create a circular ssDNA and releases itself from the 5' end of the DNA 5: The ori region of a plasmid is critical for: A: determining the host range of the plasmid. B: regulating copy number C: the level of plasmid supercoiling D: determining whether the plasmid will be compatible with a second plasmid. 6: Which of the following are true concering the incompatibility of plasmids? A: Two plasmids are incompatible if they have very different origins of replication. B: The appropriate copy number of two incompatible relaxed plasmids in a bacterium will be shared. C: The segregation of incompatible relaxed plasmids to the daughter cells is random. D: After many generations of bacterial growth, it is most likely that bacteria will contain only one and not both of the incompatible plasmids. 7: In the process of Methyl Directed Mismatch Repair: A: damage to DNA that causes slight distortions in the DNA helix such as base mismatches. B: the enzyme MutS scans and binds the damaged DNA. C: MutH is an endonuclease that introduces a cut at the nearest hemimethylated DNA site in the unmethylated strand....
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