Biochemistry Questions and Answers – Biosynthesis and Degradation of Nucleotides

This set of Biochemistry Multiple Choice Questions & Answers (MCQs) focuses on “Biosynthesis and Degradation of Nucleotides”.

1. An amino group donated by glutamine is attached at C-1 of PRPP, this results in ____________
a) 5-phosphoribosylamine
b) 4-phosphoribosylamine
c) 3-phosphoribosylamine
d) 2-phosphoribosylamine
View Answer

Answer: a
Explanation: An amino group donated by glutamine is attached at C-1 of PRPP, this results in 5-phosphoribosylamine.

2. The first intermediate with a complete purine ring is ____________
a) Inosinate
b) Formate
c) Aspartate
d) Glycine
View Answer

Answer: a
Explanation: The first intermediate with a complete purine ring is inosinate.

3. Which of the following is an important precursor in the purine pathway?
a) Glycine
b) Aspartate
c) Glutamine
d) Leucine
View Answer

Answer: a
Explanation: Aspartate is important precursor in pyrimidine pathway.
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4. Which of the following is an important precursor in pyrimidine pathway?
a) Glycine
b) Aspartate
c) Glutamine
d) Leucine
View Answer

Answer: b
Explanation: Glycine is an important precursor in purine pathway.

5. In the first committed step of pyrimidine biosynthesis, the reaction is catalyzed by ____________
a) Adenylate kinase
b) Aspartate transcarbamoylase
c) Dihyhroorotase
d) Cytidylate synthase
View Answer

Answer: b
Explanation: Carbamoyl phosphate reacts with aspartate to yield N-carbamoylaspartate in the first committed step of pyrimidine biosynthesis catalyzed by aspartate transcarbamoylase.
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6. Phosphorylation of AMP to ADP is promoted by ____________
a) Adenylate kinase
b) Aspartate transcarbamoylase
c) Dihyhroorotase
d) Cytidylate synthase
View Answer

Answer: a
Explanation: Phosphorylation of AMP to ADP is promoted by adenylate kinase.

7. CTP is formed from UTP by the action of ____________
a) Adenylate kinase
b) Aspartate transcarbamoylase
c) Dihyhroorotase
d) Cytidylate synthase
View Answer

Answer: d
Explanation: CTP is formed from UTP by the action of cytidylate synthase.
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8. Conversion of dUMP to dTMP is catalyzed by ____________
a) Thymidylate synthase
b) Dihydrofolate reductase
c) Dihyhroorotase
d) Cytidylate synthase
View Answer

Answer: a
Explanation: Conversion of dUMP to dTMP is catalyzed by thymidylate synthase.

9. Adenosine deaminase deaminates adenosine to ____________
a) Hypoxanthine
b) Inosine
c) Xanthine
d) Guanosine
View Answer

Answer: b
Explanation: Adenosine is deaminated to inosine by adenosine deaminase.
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10. Which of the following is degraded to methylmalonyl semialdehyde?
a) Glutamine
b) Tyrosine
c) Thymine
d) Leucine
View Answer

Answer: c
Explanation: Thymine is degraded to methylmalonyl semialdehyde.

Sanfoundry Global Education & Learning Series – Biochemistry.

To practice all areas of Biochemistry, here is complete set of 1000+ Multiple Choice Questions and Answers.

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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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