1. Both strands of DNA serve as templates concurrently in
A. replication
B. excision repair
C. mismatch repair
D. none of these
2. Proofreading activity to maintain the fidelity of DNA synthesis
A. occurs after the synthesis has been completed
B. is a function of the 3'-5' exonuclease activity of the DNA polymerases
C. requires the presence of an enzyme separate from the DNA polymerases
D. occurs in prokaryotes but not eukaryotes
3. Which of the following repairs nicked DNA by forming a phosphodiester bond between adjacent nucleotides?
A. Helicase
B. DNA gyrase
C. Topoisomerases
D. DNA ligase
4. The enzyme that catalyzes the synthesis of DNA is called
A. DNA polymerase
B. DNA gyrase
C. DNA ligase
D. helicase
5. Which of the following possesses both 5'-3' and 3'-5' exonuclease activity?
A. Kornberg enzyme
B. DNA polymerase III
C. Taq DNA polymerase
D. None of these
6. Which of the following statements on replication in E.coli is correct?
A. It occurs in a unidirectional manner
B. It occurs in bidirectional manner
C. Always uses T7 DNA polymerase when infected by T7 phage
D. Occurs only when Φ phase has infected
E. coli
7. The replication of chromosomes by eukaryotes occurs in a relatively short period of time because
A. the eukaryotes have more amount of DNA for replication
B. the eukaryotic replication machinery is 1000 times faster than the prokaryotes
C. each chromosome contains multiple replicons
D. eukaryotic DNA is always single stranded
8. In E.coli, which enzyme synthesizes the RNA primer for Okazaki fragments?
A. DnaA
B. DnaC
C. DnaG
D. all of these
9. During which of the following process a new copy of a DNA molecule is precisely synthesized?
A. Trasformation
B. Transcription
C. Translation
D. Replication
10. DNA gyrase is inhibited by
A. tetracycline
B. nalidixic acid
C. both (a) and (b)
D. cephalosporin
11. Which of the following enzymes unwind short stretches of DNA helix immediately ahead of a replication fork?
A. DNA polymerases
B. Helicases
C. Single-stranded binding proteins
D. Topoisomerases
12. During DNA replication in prokaryotes, synthesis begins on the circular chromosome
A. always at the same place
B. at any stretch of DNA that is high in AT pairs
C. randomly on the chromosome
D. at the promoter
13. DNA replication rates in prokaryotes are approximately of the order of
A. 10 bases per second
B. 1,00 bases per second
C. 1,000 bases per second
D. 10,000 bases per second
14. Which of the following lacks 3'-5' exonuclease activity?
A. Short fragment of DNA polymerase I
B. Taq DNA polymerase
C. T4 DNA ligase
D. All of the above
15. The synthesis of DNA by DNA polymerase occurs in the
A. 3' to 5' direction
B. 5' to 5' direction
C. 5' to 3' direction
D. 3' to 3' direction