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DNA Replication MCQ Questions & Answers

DNA Replication MCQs : This section focuses on the "DNA Replication". These Multiple Choice Questions (MCQs) should be practiced to improve the DNA Replication skills required for various interviews (campus interview, walk-in interview, company interview), placement, entrance exam and other competitive examinations.




Question 1

Both strands of DNA serve as templates concurrently in

A. replication
B. excision repair
C. mismatch repair
D. none of the above

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Question 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

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Question 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

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Question 4

The enzyme that catalyzes the synthesis of DNA is called

A. DNA polymerase
B. DNA gyrase
C. DNA ligase
D. helicase

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Question 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

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Question 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 λ phase has infected E. coli

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Question 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

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Question 8

In E.coli, which enzyme synthesizes the RNA primer for Okazaki fragments?

A. DnaA
B. DnaC
C. DnaG
D. All of the above

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Question 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

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Question 10

DNA gyrase is inhibited by

A. tetracycline
B. nalidixic acid
C. Both A and B
D. cephalosporin

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Question 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

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Question 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

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Question 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

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Question 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

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Question 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

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Question 16

Both strands of DNA serve as templates concurrently in

A. replication
B. excision repair
C. mismatch repair
D. none of these

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Question 17

DNA gyrase is inhibited by

A. tetracycline
B. nalidixic acid
C. both (a) and (b)
D. cephalosporin

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Question 18

In E.coli, which enzyme synthesizes the RNA primer for Okazaki fragments?

A. DnaA
B. DnaC
C. DnaG
D. all of these

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Question 19

DNA unwinding is done by ____________

A. Ligase
B. Helicase
C. Topoisomerase
D. Hexonuclease

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Question 20

Eukaryotes differ from prokaryote in mechanism of DNA replication due to ____________

A. Use of DNA primer rather than RNA primer
B. Different enzyme for synthesis of lagging and leading strand
C. Discontinuous rather than semi-discontinuous replication
D. Unidirectional rather than semi-discontinuous replication

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Question 21

How many copies (approximately) of DNA polymerase III are present in a typical bacterial cell?

A. 10
B. 50
C. 100
D. 200

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Question 22

How many types of replication models were considered before the semiconservative nature of DNA replication was confirmed?

A. 1
B. 2
C. 3
D. 4

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Question 23

Movement of the replication fork generates ________________ in the unreplicated portion of DNA.

A. positive supercoils
B. negative supercoils
C. untranslated regions
D. amino acid substitutions

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Question 24

Semi-conservative DNA replication was first demonstrated in ____________

A. Drosophila melanogaster
B. Escherichia coli
C. Streptococcus pneumonae
D. Drosophila melanogaster

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Question 25

Temperature-sensitive mutants can not replicate their chromosomes at non-permissive temperatures.

A. True
B. False

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Question 26

The lagging strand is synthesized discontinuously.

A. True
B. False

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Question 27

What is DNA replication?

A. Conservative
B. Non-conservative
C. Semi-conservative
D. None of the mentioned

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Question 28

What is the reaction in DNA replication catalyzed by DNA ligase?

A. Addition of new nucleotides to the leading strand
B. Addition of new nucleotide to the lagging strand
C. Formation of a phosphodiester bond between the 3’-OH of one Okazaki fragment and the 5’-phosphate of the next on the lagging strand
D. Base pairing of the template and the newly formed DNA strand

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Question 29

When was DNA polymerase III discovered as the major enzyme behind DNA replication in bacteria?

A. 1949
B. 1959
C. 1969
D. 1989

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Question 30

Which enzyme joins the Okazaki fragments into a continuous strand?

A. gyrase
B. topoisomerase
C. ligase
D. helicase

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Question 31

Which enzyme removes the positive supercoils generated when the replication fork?

A. helicase
B. endonuclease
C. exonuclease
D. gyrase

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Question 32

Which enzyme used to join bits of DNA?

A. DNA polymerase
B. DNA ligase
C. Endonuclease
D. Primase

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Question 33

Which isotopes were used by the researchers who first confirmed the semiconservative nature of DNA replication?

A. Nitrogen
B. Carbon
C. Oxygen
D. Sulfur

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Question 34

Which of the following enzyme is responsible for initiating DNA replication?

A. polymerase
B. ligase
C. primase
D. gyrase

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Question 35

Which of the following enzymes is the principal replication enzyme in E. coli?

A. DNA polymerase I
B. DNA polymerase II
C. DNA polymerase III
D. None of the mentioned

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Question 36

Which of the following enzymes remove supercoiling in replicating DNA ahead of the replication fork?

A. DNA polymerases
B. Helicases
C. Primases
D. Topoisomerases

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Question 37

Which of the following is true about DNA polymerase?

A. It can synthesize DNA in the 5’ to 3’ direction
B. It can synthesize DNA in the 3’ to 5’ direction
C. It can synthesize mRNA in the 3’ to 5’ direction
D. It can synthesize mRNA in the 5’ to 3’ direction

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Question 38

Who made the discovery that one DNA strand is synthesized discontinuously in fragments?

A. Francis Crick
B. Reiji Okazaki
C. James Watson
D. Louis Pasteur

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Question 39

Double-helix structure of DNA is discovered by___________

A. Gobind Khurana
B. Nirenberg
C. Watson and Crick
D. Darwin

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Question 40

Base sequence of each parental strand considered to synthesis new complementary strand.

A. True
B. False

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Question 41

How many numbers of replicon is found in E.coli?

A. Five replicon
B. Two replicon
C. Single replicon
D. Multiple replicon

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Question 42

Name the protein, which is responsible for the formation of RNA primer?

A. Topoisomerase
B. Gyrase
C. Helicase
D. Primase

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Question 43

Name the protein, which is used for termination of replication?

A. DnaC
B. SSB
C. Tus protein
D. DNA polymerase

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Question 44

What is a mode of replication in E.coli?

A. Intermediate
B. Dispersive
C. Conservative
D. Semiconservative

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Question 45

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

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Question 46

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

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Question 47

Which of the following protein is required for connecting Okazaki fragments?

A. Scaffold protein
B. Helicase
C. Primase
D. DNA gyrase

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Question 48

Which of the following would relax negatively supercoiled DNA?

A. DNA gyrase
B. Type I topoisomerase
C. Collagen
D. Elastin

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