Apentix/AP Biology/Unit 2: Cell Structure and Function/Question
AP Biologymediummcq1 pt

Which statement correctly distinguishes integral membrane proteins from peripheral membrane proteins?

A.Peripheral proteins span the membrane twice and form gated pores
B.Only peripheral proteins can drift laterally within the plane of the membrane
C.Integral proteins sit within the bilayer's hydrophobic core, while peripheral proteins attach loosely to membrane surfaces
D.Integral proteins float free in the cytosol until signals anchor them briefly

Explanation

Core Concept

Integral proteins contain hydrophobic amino acid stretches that partition into the lipid interior, often crossing the whole bilayer as transmembrane helices. Dislodging them generally requires detergents that mimic the bilayer environment. Peripheral proteins lack such segments and bind through weak electrostatic contacts with head groups or other proteins, so mild salt solutions can release them without dissolving the membrane.

Correct Answer

CIntegral proteins sit within the bilayer's hydrophobic core, while peripheral proteins attach loosely to membrane surfaces

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