Multiple Choice
Which of the following molecules is a phospholipid commonly found in the lipid bilayer of cell membranes?
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8. Membrane Structure
The Lipid Bilayer
Multiple Choice
In a typical mammalian plasma membrane, where is cholesterol primarily located within the lipid bilayer?
A
Intercalated between phospholipid fatty acid tails in both leaflets of the bilayer
B
Confined to the cytosolic surface as a peripheral lipid bound to cytoskeletal proteins
C
Present only within transmembrane protein channels to line their hydrophilic pores
D
Covalently attached to the polar head groups of phospholipids on the extracellular leaflet only
Verified step by step guidance1
Recall the basic structure of the plasma membrane, which is a lipid bilayer composed mainly of phospholipids with hydrophilic heads facing outward and hydrophobic fatty acid tails facing inward.
Understand that cholesterol is a lipid molecule that interacts with the phospholipids in the membrane, affecting its fluidity and stability.
Recognize that cholesterol is amphipathic, having a small polar hydroxyl group and a large hydrophobic steroid ring structure, which allows it to insert itself within the hydrophobic core of the bilayer.
Identify that cholesterol is not confined to one leaflet or bound peripherally to proteins, but rather intercalates between the fatty acid tails of phospholipids in both leaflets of the bilayer.
Conclude that cholesterol's primary location is within the hydrophobic interior of the membrane, between the fatty acid tails, helping to modulate membrane fluidity and permeability.
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