Stbp Questions 1 - practice Question & Answers DNA replication and recombination

Stbp Questions 1 - practice Question & Answers DNA replication and recombination Quizzes: DNA Replication and Recombination Part A: MCQ (19 marks). Please circle the correct answer. 1. The protein that progressively unwinds DNA ahead of each replication fork is called A. primases. C. topoisomerases. D. telomeres. 2. Which function can be carried out by DNA replication proteins? a) Topoisomerases wind the DNA into a double-helix. b) DNA ligase can initiate new DNA chains c) SSB converts double-stranded DNA into single-stranded DNA. d) Helicases break hydrogen bonds in the DNA. 3. The attB site is required for in E. coli. A. homologous recombination B. site-specific recombination C. illegitimate recombination D. non-homologous recombination E. all of the above 4. Which of the following statements is best to describe the observation (as in the picture below) made by David Dressler and Hunt Potter in 1976? A. Plasmid can be digested using restriction enzymes. B. Their findings rejected the hypothesis made by Robin Holliday. C. Bacteria contain extrachromosomal DNA D. They observed recombination intermediate. 5. Illegitimate recombination is a broad term designating recombination events that A. are independent of RecA. B. requires two large DNA sequences with similar or almost identical base pair sequence. C. forms Holliday structure as the intermediate. D. are dependent of RecA. 6. In the Meselson-Stahl DNA replication experiment, what percent of the DNA was composed of one light strand and one heavy strand after one generation of growth in 14N containing growth media? A 0 B 25 C 50 D 100 7. The diagram below shows a short section of DNA molecule before and after replication. If the nucleotides used to replicate the DNA were radioactive, which strands in the replicated molecules would be radioactive? A. II and III only B. I and III only C. I and II only D. I, II, III and IV 8. Which of the following proteins is resolvase in E. coli? A. RuvA B. RuvB D. RecA 9. If DNA polymerase I were mutated so that all its enzymatic activities were inactive, which part of replication would be most affected? a) synthesis of Okazaki pieces b) joining of Okazaki pieces c) proof-reading of DNA d) adjusting of supercoiling 10. Special structures called telomeres are needed in eukaryotic cells but not bacteria because b. Eukaryotic cell have more than one chromosome c. Eukaryotic cells contain a nucleus d. Eukaryotic cells contain more forms of DNA polymerases 11. Why is an RNA primer necessary for DNA replication? a. The RNA primer is necessary for the activity of DNA ligase. b. The RNA primer creates the 5’ and 3’ ends of the strand. 12. This type of recombination is important for the integration of viral genomes into bacterial chromosomes a. homologous recombination