Structure of dsDNA Multiple Choice Questions(MCQs) & Answers

1 Which of them is used to introduce negative supercoiling in DNA?

A Type 1 topoisomerase

B Ethidium bromide

C Gyrase/ type 2 topoisomerase

D SYBR gold

View Answer

Answer: Gyrase/ type 2 topoisomerase

2 What is the term given to the supercoiling of circular DNA?

A Twist number

B Linking number

C Writhe number

D Cross-linking

View Answer

Answer: Linking number

3 Which of this factor is not responsible for thermal denaturation of DNA?

A PH

B Temperature

C Ionic strength

D Humidity

View Answer

Answer: Humidity

4 The stability and formation of G-quadruplex depends on __________

A Monovalent cation

B Divalent cation

C Bivalent cation

D Pentavalent ion

View Answer

Answer: Monovalent cation

5 Name the nitrogenous base which is found in abundance in G-quadruplex?

A Adenine

B Guanine

C Cytosine

D Thymine

View Answer

Answer: Guanine

6 The third strand of triple helix is paired in which scheme?

A Hoogsteen base pair scheme

B Intermolecular base pair scheme

C Intramolecular base pair scheme

D G-quartet scheme

View Answer

Answer: Hoogsteen base pair scheme

7 Which one of the following statement is INCORRECT for Z-DNA?

A Left-handed DNA

B Mostly found in alternating purine-pyrimidine sequences

C Only one deep, narrow groove

D Anti glycosidic bond conformation

View Answer

Answer: Anti glycosidic bond conformation

8 How many base pairs are there in every helical turn of Watson-Crick double helix model?

A 32.3

B 11.6

C 20

D 10.4

View Answer

Answer: 10.4

9 Which form of DNA is described by Watson-Crick model?

A B-DNA

B Z-DNA

C A-DNA

D Quadraplex DNA

View Answer

Answer: B-DNA

10 Who described the structure of DNA double helix?

A Peter Mitchell

B Andre Jagendorf

C Ernest Uribe

D Watson and Crick

View Answer

Answer: Watson and Crick

11 Levene investigated and found that the nucleic acid is composed of poly-nucleotides and each nucleotide is composed of one base, a sugar molecule and a phosphate. This was performed on the genome of________________

A Bacteria

B Fungi

C WBCs

D Yeast

View Answer

Answer: Yeast

12 In the late 1970s non double helical form of DNA was also suggested but was discarded on the basis of certain factors. Which of the following is not a factor responsible?

A X-ray crystallography

B Nuclein

C Topoisomerase

D Nucleosome core particle

View Answer

Answer: Nuclein

13 With respect to the importance of hydrogen bonding and DNA double helix stability, which of the following statements is false?

A Favorable tautomeric form of nucleotide bases

B Contributes to the thermodynamic stability

C Decreases the entropy

D Specificity of base pairing

View Answer

Answer: Decreases the entropy

14 In a DNA double helix the bases are held together by hydrogen bonds. These hydrogen bonds are _________

A Covalent bonds

B Non-covalent bonds

C Ionic bonds

D Van der Waals forces

View Answer

Answer: Non-covalent bonds

15 The hydrogen bonds formed during A and T bonding occurs between C6NH2 of A and _____

A C4O of T

B PO3–

C C6O of A

D C1O of T

View Answer

Answer: C4O of T

16 What should be the complementary strand of 3’….ATGGCTTGA….5’?

A 3’….TACCGAACT….5’

B 5’….TACCGAACT….3’

C 3’….TAGGCAAGT….5’

D 5’….TAGGCAAGT….3’

View Answer

Answer: 5’….TACCGAACT….3’

17 In 1952, an unambiguous established work in the laboratory of Alexander Todd led to the discovery of _____________

A Chemical nature of DNA

B X-ray diffraction structure of DNA

C 3’-5’ phosphodiester linkage regularly links the nucleotides of DNA

D Nucleic acid strands are held together by hydrogen bonds

View Answer

Answer: 3’-5’ phosphodiester linkage regularly links the nucleotides of DNA

18 In early 1950s high quality X-ray diffraction photographs of DNA suggesting the DNA being double helix and composed of two nucleotide strands. Who took those photographs?

A Rosalind Franklin

B William Asbury

C Francis H. Crick and James D. Watson

D Rosalind Franklin and Maurice Wilkins

View Answer