Biochemistry Questions and Answers – Nucleic Acid Chemistry

This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Nucleic Acid Chemistry”.

1. What happens in hypochromicity?
a) When DNA is in bound form, there is decrease in absorption of UV light
b) When DNA is in bound form, there is increase in absorption of UV light
c) When DNA is in unbound form, it is more stable
d) When DNA is in unbound form, there is decrease in absorption of UV light
View Answer

Answer: a
Explanation: It describes the decrease in absorbance of UV light in a double stranded DNA.

2. What happens in hyperchromicity?
a) When DNA is in bound form, there is decrease in absorption of UV light
b) When DNA is in bound form, there is increase in absorption of UV light
c) When DNA is in unbound form, it is more stable
d) When DNA is in unbound form, there is increase in absorption of UV light
View Answer

Answer: d
Explanation: It describes the increase in absorption of UV light in a single stranded DNA.

3. Which of the following is true about tm?
a) It can be termed as renaturation temperature
b) The higher the content of G ≡ C base pairs, the higher the tm
c) The higher the content of A = T base pairs, the higher the tm
d) The higher the content of G ≡ C base pairs, the lower the tm
View Answer

Answer: b
Explanation: Higher GC content, the melting temperature will be higher because GC content has 3 hydrogen bond and AT has two hydrogen bonds.
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4. Which of the following is false?
a) The stability of an RNA-DNA hybrid is generally intermediate between that of RNA and DNA
b) RNA duplexes are more stable than DNA duplexes
c) DNA duplexes are more stable than RNA duplexes
d) DNA duplexes are less stable than RNA- DNA hybrid
View Answer

Answer: c
Explanation: RNA duplexes are more stable than DNA duplexes.

5. DNA denaturation is measured by absorbance at ___________
a) 220nm
b) 230nm
c) 250nm
d) 260nm
View Answer

Answer: d
Explanation: At 260nm absorbance, DNA denaturation is measured.
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6. Which of the following is false about denaturation?
a) Disruption of hydrogen bonds
b) Disruption of phosphodiester linkage
c) Loss of helical structure of DNA
d) It is resulted as a result of change in pH or increase in temperature
View Answer

Answer: b
Explanation: Phosphodiester linkages are not broken by denaturation.

7. Which of the following nucleotides is not present in RNA?
a) AMP
b) GMP
c) CMP
d) TMP
View Answer

Answer: d
Explanation: Thymidine monophosphate is present in DNA.
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8. Which of the following nucleotides is not present in DNA?
a) AMP
b) GMP
c) CMP
d) UMP
View Answer

Answer: d
Explanation: Uridine monophosphate is present in RNA.

9. Which of the following is false?
a) RNA does not obey Chargaff’s rule
b) DNAs can be identified by Orcinol color reaction
c) In RNA OH group is present at 2’ position
d) Alkali hydrolyses RNA to 2’3’-cyclic diesters
View Answer

Answer: b
Explanation: RNAs can be identified by Orcinol color reaction.
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10. Which of the following involves carrying genetic information from DNA for protein synthesis?
a) m-RNA
b) t-RNA
c) r-RNA
d) sn-RNA
View Answer

Answer: a
Explanation: Messenger RNA carries genetic information from DNA for protein synthesis.

Sanfoundry Global Education & Learning Series – Biochemistry.

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Manish Bhojasia - Founder & CTO at Sanfoundry
Manish Bhojasia, a technology veteran with 20+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He lives in Bangalore, and focuses on development of Linux Kernel, SAN Technologies, Advanced C, Data Structures & Alogrithms. Stay connected with him at LinkedIn.

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