Apentix/AP Biology/Unit 2: Cell Structure and Function/Question
AP Biologyhardmcq1 pt

In familial hypercholesterolemia, liver cells carry few functional LDL receptors at their surfaces, and blood cholesterol climbs to dangerous levels. Which membrane process do the missing receptors normally carry out?

A.Simple diffusion of cholesterol esters directly through the bilayer
B.Active export of cholesterol into bile against its gradient
C.Antibody tagging of LDL particles for destruction in the bloodstream
D.Receptor-mediated endocytosis, binding LDL particles and drawing them into coated vesicles

Explanation

Core Concept

LDL receptors cluster in clathrin-coated pits, latch onto circulating LDL particles, and the membrane invaginates to internalize them as vesicles that mature into endosomes. Cells without working receptors cannot clear LDL from the blood, which is why plasma cholesterol accumulates in affected individuals. The route is specific and saturable, hallmarks of receptor-driven uptake rather than bulk sampling.

Correct Answer

DReceptor-mediated endocytosis, binding LDL particles and drawing them into coated vesicles

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