Biochemistry Questions on “Biosynthesis of Cholesterol, Steroids and Isoprenoids”.
1. Generally, the receptors for steroid hormones reside at ___________
A. Nucleoplasm
B. Nuclear membrane
C. Cytoplasm
D. Plasma membrane
Answer: A
Clarification: The receptors for steroid hormones reside at nucleoplasm.
2. Steroids have ___________
A. Sterol nucleus with two alkyl chain attached to the ring D of cholesterol
B. Sterol nucleus with two CH3 between C and D ring and A and B ring of cholesterol
C. Sterol nucleus without CH3 between C ring and D ring of cholesterol
D. Sterol nucleus but lack the alkyl chain attached to the ring D of cholesterol
Answer: D
Clarification: Steroids have a sterol nucleus but lack the alkyl chain attached to the ring D of cholesterol.
3. Prednisolone and prednisone are chemically ___________
A. Steroids
B. Glycerol derivatives
C. Non-steroid anti-inflammatory drug
D. Amino alcohols
Answer: A
Clarification: Prednisolone and prednisone are chemically steroids.
4. The essential intermediates in the pathway from acetate to cholesterol are ___________
A. Acetic acid
B. Ethylene
C. Isoprene units
D. Methane
Answer: C
Clarification: Isoprene units are the essential intermediates in the pathway from acetate to cholesterol.
5. Which is the first intermediate in cholesterol synthesis?
A. Mevalonate
B. Isoprene
C. Squalene
D. Ethylene
Answer: A
Clarification: The first intermediate in cholesterol synthesis is mevalonate.
6. How many carbons are present in HMG co-A?
A. 2
B. 3
C. 5
D. 6
Answer: D
Clarification: Two molecules of acetyl co-A condense to form acetoacetyl co-A, which condenses with the third molecule of acetyl co-A to yield a six-carbon compound HMG co-A.
7. Which of the following is the major point of regulation on the pathway to cholesterol?
A. Thiolase
B. HMG co-A synthase
C. HMG co-A reductase
D. Pyruvate kinase
Answer: C
Clarification: HMG co-A reductase is the major point of regulation on the pathway to cholesterol.
8. Which of the following is the integral membrane protein of smooth ER?
A. Thiolase
B. HMG co-A synthase
C. HMG co-A reductase
D. Pyruvate kinase
Answer: C
Clarification: HMG co-A reductase is the integral membrane protein of smooth ER.
9. How many carbons are present in geranyl pyrophosphate?
A. 8
B. 9
C. 10
D. 11
Answer: C
Clarification: Geranyl pyrophosphate is a 10-carbon chain.
10. Which of the following regulates the female reproductive cycle?
A. Progesterone
B. Testosterone
C. Estrogens
D. Glucocorticoids
Answer: A
Clarification: Testosterone and estrogens which influence the development of secondary sexual characteristics in males and females, respectively.
Glucocorticoids help regulate gluconeogenesis and reduce the inflammatory response.