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
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
Question 2
What is the approximate size (in kb) of the E. coli genome?
A. 3000 kilobase
B. 4500 kilobase
C. 5500 kilobase
D. 6500 kilobase
Question 3
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
Question 4
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
Question 5
DNA can be sequenced by the
A. chemical method
B. chain termination procedure
C. both (a) and (b)
D. physical method
Question 6
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
Question 7
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
Question 8
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
Question 9
A cesium chloride will separate DNA molecules by
A. absorption
B. resorption
C. density
D. adhesion
Question 10
Messelsen and Stahl model of replication was called
A. conservative replication
B. semi-conservative replication
C. dispersive replication
D. Cri du Chat
Question 11
Enzymes, responsible for unraveling short segments of DNA is
A. DNA polymerase
B. helicase
C. DNA ligase
D. primase
Question 12
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
Question 13
Which of the following would not contain DNA?
A. Yeast
B. Bacteria
C. Glass crystals
D. Mold
Question 14
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
Question 15
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
Question 16
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
Question 17
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
Question 18
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
Question 19
Proteins involved in opening a replication bubble are
A. DNA helicases
B. single stranded binding proteins
C. ligase
D. DNA topoisomerase
Question 20
Klenow fragment without free nucleotides exhibits
A. exonuclease activity
B. endonuclease activity
C. nickase activity
D. no activity
Question 21
The most common liquid volumes in molecular biology are measured in
A. ml
B. μl
C. nl
D. 1
Question 22
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
Question 23
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
Question 24
Which is the largest among the followings?
A. Nucleotide
B. Nitrogenous base
C. Phosphate
D. Carbon
Question 25
Which DNA polymerase removes RNA primers in DNA synthesis?
A. Polymerase I
B. Polymerase II
C. Polymerase III
D. none of these
Question 26
Okazaki fragments occur during
A. transformation
B. replication
C. polymerase reaction
D. synthesis
Question 27
Enzyme, responsible for proofreading base pairing is
A. DNA polymerase
B. Telomerase
C. Primase
D. DNA ligase
Question 28
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
Question 29
DNA replication takes place in which direction?
A. 3' to 5'
B. 5 'to 3'
C. Randomly
D. Vary from organism to organism
Question 30
Which of the following enzyme adds complementary bases during replication?
A. Helicase
B. Synthesase
C. Replicase
D. Polymerase
Question 31
The accepted hypothesis for DNA replication is
A. conservative theory
B. dispersive theory
C. semi-conservative theory
D. evolutionary theory
Question 32
What is the main damaging effect of UV radiation on DNA?
A. Depurination
B. Formation of thymine dimers
C. Single strand break
D. Dehydration
Question 33
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
Question 34
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
Question 35
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
Question 36
Telomeres are usually rich in which nucleotide?
A. Adenine
B. Guanine
C. Thymine
D. Cytosine
Question 37
In DNA, guanine pairs with
A. Adenine
B. Cytosine
C. Thymine
D. Uracil
Question 38
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
Question 39
DNAs when charged, migrate in a gel towards the
A. positive pole
B. negative pole
C. will not migrate
D. none of these