NUCLEIC ACIDS Questions and Answers pdf :-

1. Because DNA is a highly charged polyanion, its stability to heat denaturation

A. does not depend on hydrophobic interactions
B. increases with increasing salt
C. is independent of G – C content
D. decreases with increasing salt

Answer: B

2. The sugar in RNA is __________ , the sugar in DNA is __________

A. deoxyribose, ribose
B. ribose, deoxyribose
C. ribose, phosphate
D. ribose, uracil

Answer: B

3. Nucleoside is a pyrimidine or purine base

A. covalently bonded to a sugar
B. ionically bonded to a sugar
C. hydrogen bonded to a sugar
D. none of the above

Answer: A

4. In gel electrophoresis, what fragments will move most quickly through a gel?

A. Large fragments
B. Small fragments
C. Large genome
D. None of these

Answer: B

5. Which pyrimidine base contains an amino group at carbon 4?

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

Answer: A

6. Nucleotide bases and aromatic amino acids absorb light respectively at

A. 280 and 260 nm
B. 260 and 280 nm
C. 270 and 280 nm
D. 260 and 270 nm

Answer: B

7. The glycosidic bonds in DNA and RNA

A. connect the sugar to the base
B. can be hydrolyzed by OH- ion
C. stabilize Watson-Crick H-bonds
D. are free to rotate over about 180°

Answer: A

8. Nucleic acids can be analyzed experimentally by their

A. molecular weight
B. absorption of visible light
C. absorption of uv light
D. none of these

Answer: C

9. Thymidine

A. can participate in hydrophobic interactions due to its methyl group
B. is replaced by uracil in RNA
C. normally forms two hydrogen bonds with adenosine
D. all of the above

Answer: D

10. A nucleotide consists of

A. a sugar, a base and a phosphate
B. a sugar and a phosphate
C. paired bases
D. a sugar, a base and three phosphates

Answer: A

NUCLEIC ACIDS Questions and Answers ::

11. A five carbon sugar lacking a hydrogen at the number 2 carbon is found in

A. DNA
B. RNA
C. mRNA
D. rDNA

Answer: A

12. The unfavourable free energy associated with not satisfying a hydrogen bond after formation of the double helix is approximately

A. 10 kJ/mol
B. 20 kJ/mol
C. 25 kJ/mol
D. 30 kJ/mol

Answer: B

13. The most stabilizing force for nucleic acids is

A. hydrogen bonds
B. electrostatic bond
C. Van der Waals
D. conformational entropy

Answer: C

14. A purine with an amine (NH2) group on the 6th carbon is

A. adenine
B. cytosine
C. thymine
D. guanine

Answer: A

15. Which of the following is found on RNA but not DNA?

A. Uracil
B. Deoxyribose
C. Phosphate
D. Adenine

Answer: A

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