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DNA Structure and Replication MCQ Questions & Answers

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

Question 1

The nucleosome consists of histone

A. octamer and 146 bp of DNA
B. tetramer and 146 bp of DNA
C. hexamer and 146 bp of DNA
D. none of the above

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Question 2

Enzymes, responsible for unraveling short segments of DNA is

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

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Question 3

The chromosomal DNA complexes with

A. three types of histone as H1, H2A and H4
B. five types of histone as H1, H2A, H2B, H3 and H4
C. four types of histone as H1, H2A, H3 and H4
D. two types of histone as H1 and H4

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Question 4

What is the only common methylation in the DNA of eukaryotes?

A. Adenosine in GpA dinucleotides
B. Guanosine in ApGpA trinucleotides
C. Cytosine in CpG dinucleotides
D. None of the above

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Question 5

DNAs when charged, migrate in a gel towards the

A. positive pole
B. negative pole
C. will not migrate
D. none of these

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Question 6

DNA can be sequenced by the

A. chemical method
B. chain termination procedure
C. both (a) and (b)
D. physical method

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Question 7

Enzyme, responsible for proofreading base pairing is

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

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Question 8

The accepted hypothesis for DNA replication is

A. conservative theory
B. dispersive theory
C. semi-conservative theory
D. evolutionary theory

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Question 9

In DNA, guanine pairs with

A. Adenine
B. Cytosine
C. Thymine
D. Uracil

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Question 10

What bands will be observed in a cesium chloride gradient after two rounds of replication?

A. One light, one medium and one heavy band
B. One light and one medium band
C. One medium band
D. One medium and one heavy band

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Question 11

Which of the following would not contain DNA?

A. Yeast
B. Bacteria
C. Glass crystals
D. Mold

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Question 12

The overall conclusion of the Hershey-Chase experiment was that

A. DNA was responsible for heredity
B. proteins and DNA were responsible for heredity
C. the ratio of Adenine to thymine was always the same
D. phage DNA was similar to bacterial DNA

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Question 13

DNA helicase is used to

A. unwind the double helix
B. interact the double helix closely
C. break a phosphodiester bond in DNA strand
D. none of the above

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Question 14

What is the range of melting point temperatures (Tm) for most DNA molecules?

A. 50 to 60°C
B. 60 to 80°C
C. 70 to 90°C
D. 80 to l00°C

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Question 15

Which of the following enzyme adds complementary bases during replication?

A. Helicase
B. Synthesase
C. Replicase
D. Polymerase

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Question 16

Taylor, Woods and Hughes labeled Vicia DNA by allowing new DNA synthesis in the presence of radioactive thymine. After DNA replication (S phase of the cell cycle), it was observed that

A. only one chromatid of a chromosome was labeled
B. both chromatids of a chromosome were labeled
C. both (a) and (b)
D. neither chromatid was labeled

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Question 17

Messelsen and Stahl model of replication was called

A. conservative replication
B. semi-conservative replication
C. dispersive replication
D. Cri du Chat

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Question 18

DNA replication takes place in which direction?

A. 3' to 5'
B. 5 'to 3'
C. Randomly
D. Vary from organism to organism

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Question 19

DNA gyrase in E. coli

A. adds positive supercoils to chromosomal DNA
B. can be inhibited with antibiotics
C. is required only at the oriC site
D. performs the same function as helicase in eukaryotes

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Question 20

In DNA, there are

A. five bases known as adenine, guanine, thymine, tryptophan and cytosine
B. four bases known as adenine, guanine, thymine and cytosine
C. three bases known as adenine, guanine and cytosine
D. only two bases known as adenine and cytosine

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Question 21

Klenow fragment without free nucleotides exhibits

A. exonuclease activity
B. endonuclease activity
C. nickase activity
D. no activity

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Question 22

In the study of one experiment it was found that the value of Tm for DNA is = 40° C. If the cell has 20% GC at the above Tm, then what will be value of 'Tm' if the GC% increases to 60%?

A. Remains same
B. Increases
C. Decreases
D. Can not be compared

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Question 23

Proteins involved in opening a replication bubble are

A. DNA helicases
B. single stranded binding proteins
C. ligase
D. DNA topoisomerase

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Question 24

What is the main damaging effect of UV radiation on DNA?

A. Depurination
B. Formation of thymine dimers
C. Single strand break
D. Dehydration

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Question 25

A cesium chloride will separate DNA molecules by

A. absorption
B. resorption
C. density
D. adhesion

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Question 26

Which DNA polymerase removes RNA primers in DNA synthesis?

A. Polymerase I
B. Polymerase II
C. Polymerase III
D. none of these

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Question 27

Which of the following is incorrect?

A. In DNA double helix, two strands of the DNA are bound with each other with the bases
B. Adenine always pairs with thymine
C. Guanine always pairs with the cytosine
D. None of the above

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Question 28

The 5' and 3' numbers are related to the

A. length of the DNA strand
B. carbon number in sugar
C. the number of phosphates
D. the base pair rule

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Question 29

Okazaki fragments occur during

A. transformation
B. replication
C. polymerase reaction
D. synthesis

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Question 30

Which is the largest among the followings?

A. Nucleotide
B. Nitrogenous base
C. Phosphate
D. Carbon

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Question 31

E.coli DNA polymerases II and III lack

A. 5' → 3' exonuclease activity
B. 5' → 3' endonuclease activity
C. partially 5' → 3' exonuclease activity
D. partially 5' → 3' endonuclease activity

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Question 32

If one cell has AT contents 40%, what will be the percentage of Guanine residue?

A. 60%
B. 15%
C. 30%
D. Guanine residue can not be calculated

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Question 33

In DNA double helix, the two DNA chains are held together by

A. covalent bonds between the pair of bases
B. hydrogen bonds between the pair of bases
C. ionic bonds between the pair of bases
D. none of the above

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Question 34

When DNA polymerase is in contact with guanine in the parental strand, what does it add to the growing daughter strand?

A. Phosphate
B. Cytosine
C. Uracil
D. Guanine

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Question 35

Telomeres are usually rich in which nucleotide?

A. Adenine
B. Guanine
C. Thymine
D. Cytosine

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Question 36

In sperm heads, DNA is particularly highly condensed and the histones are replaced with small basic protein called

A. protamines
B. purines
C. pyrimidines
D. all of the above

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Question 37

The most common liquid volumes in molecular biology are measured in

A. ml
B. μl
C. nl
D. 1

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Question 38

What is the approximate size (in kb) of the E. coli genome?

A. 3000 kilobase
B. 4500 kilobase
C. 5500 kilobase
D. 6500 kilobase

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Question 39

Which histone(s) are associated with the linker DNA of a nucleosome?

A. Histone H1
B. Histones H2A and H2B
C. Histone H3
D. Histone H4

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