Life Sciences Multiple Choice Questions on “DNA Replication”.
1. Double-helix structure of DNA is discovered by___________
A. Gobind Khurana
B. Nirenberg
C. Watson and Crick
D. Darwin
Answer: C
Clarification: In 1953, Watson and Crick worked out on the double – helix structure of DNA and find out the complementary nature of two strands.
2. Base sequence of each parental strand considered to synthesis new complementary strand.
A. True
B. False
Answer: A
Clarification: The two strands of DNA are separated without breakage of a covalent bond and its base sequence act as the template strand to synthesize a new complementary strand.
3. What is a mode of replication in E.coli?
A. Intermediate
B. Dispersive
C. Conservative
D. Semiconservative
Answer: D
Clarification: Meselson and Stahl in 1958 conducted an experiment and demonstrated the semiconservative replication of DNA in E.coli.
4. What is the origin of replication?
A. Particular site at which DNA replication starts
B. Site which prevents initiation
C. Random location on the DNA
D. Site at which replication terminated
Answer: A
Clarification: Origin of replication is particular sites on DNA as replication does not start at random sites. Replication starts from a particular site and proceeds bidirectionally or unidirectionally till the terminus site.
5. How many numbers of replicon is found in E.coli?
A. Five replicon
B. Two replicon
C. Single replicon
D. Multiple replicon
Answer: C
Clarification: E.coli is monorepliconic and have single replicon while eukaryotic cells contain many replication origins on a single chromosome and called multirepliconic.
6. Which of the following protein does not involve in the initiation of replication?
A. DnaA
B. SSB (Single strand binding protein)
C. DnaB
D. DnaF
Answer: D
Clarification: In eukaryotic replication, more than 20 proteins take part out of that the initiation of replication takes place in the presence of helicase, primase, SSB, DnaC, DnaA.
7. Which of the following protein is required for connecting Okazaki fragments?
A. Scaffold protein
B. Helicase
C. Primase
D. DNA gyrase
Answer: D
Clarification: After initiation, the chain elongation and joining of Okazaki fragments take place by DNA gyrase, DNA ligase, DNA polymerase.
8. Name the protein, which is used for termination of replication?
A. DnaC
B. SSB
C. Tus protein
D. DNA polymerase
Answer: C
Clarification: Tus protein is terminus binding protein which is used for termination of replication.
9. Which of the following would relax negatively supercoiled DNA?
A. DNA gyrase
B. Type I topoisomerase
C. Collagen
D. Elastin
Answer: B
Clarification: Negatively supercoiled DNA can be relaxed by topoisomerase I. It creates the nick in one strand of DNA and rotates freely to resolve supercoiling.
10. Name the protein, which is responsible for the formation of RNA primer?
A. Topoisomerase
B. Gyrase
C. Helicase
D. Primase
Answer: D
Clarification: RNA primers are generated by using protein, primase which is also known as RNA polymerase. Primers are short RNA sequences.
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