What is the primary role of cholesterol in mammalian plasma membranes at low temperatures?
Answer and explanation
Correct answer: C. Preventing close packing of phospholipids to preserve membrane fluidity
Cholesterol modulates membrane fluidity bi-directionally. At low temperatures, its bulky steroid ring prevents fatty acid chains from packing tightly, maintaining fluidity. It does not bind extracellular actin, enhance glucose permeability, or act as a flippase enzyme.
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