Question

Four statements about lipids are given below as options. Choose the statement(s) which is/are CORRECT.

• A. Cholesterol is amphipathic
• B. Self-assembly of phospholipids in water is due to hydrophobic effect
• C. The temperature at which the gel phase changes to liquid crystalline phase increases with an increase in the degree of unsaturation of fatty acyl tails
• D. The choline head group of lipids is positively charged

Hint:

Unsaturated fatty acids lower the melting/transition temperature of lipid bilayers, making membranes more fluid.

Answer 1

The Correct Option is A, B, D

(A) Cholesterol contains a polar hydroxyl group (–OH) and a large nonpolar steroid ring structure, making it amphipathic. ✔️
(B) Phospholipids self-assemble into bilayers/micelles in aqueous solution due to the hydrophobic effect—the tails avoid water while polar heads interact with it. ✔️
(C) Unsaturation introduces kinks in fatty acyl chains, reducing packing and thereby lowering the transition temperature (\(T_m\)), not increasing it. ❌
(D) The choline head group bears a positively charged quaternary ammonium group. ✔️
Thus, the correct statements are (A), (B), and (D).