Multiple Choice
In the context of the lipid bilayer, what is the primary role of cholesterol in the cell membrane?
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8. Membrane Structure
The Lipid Bilayer
Multiple Choice
In the context of the lipid bilayer, what is the primary role of cholesterol in the plasma membrane?
A
It serves as the primary polar head group that provides the membrane’s surface charge.
B
It buffers membrane fluidity by reducing phospholipid movement at high temperatures and preventing tight packing at low temperatures.
C
It covalently cross-links phospholipid tails to permanently rigidify the bilayer under all conditions.
D
It forms the main aqueous pores that allow ions to freely diffuse across the membrane.
Verified step by step guidance1
Step 1: Understand the structure of the plasma membrane, which is primarily composed of a phospholipid bilayer with embedded proteins and cholesterol molecules.
Step 2: Recognize that cholesterol is a lipid molecule interspersed among phospholipids within the bilayer, influencing membrane properties without forming covalent bonds with phospholipids.
Step 3: Analyze how cholesterol affects membrane fluidity: at high temperatures, it stabilizes the membrane by reducing excessive phospholipid movement, preventing the membrane from becoming too fluid.
Step 4: Consider the role of cholesterol at low temperatures, where it prevents phospholipids from packing too tightly, thus maintaining membrane fluidity and preventing rigidity.
Step 5: Conclude that cholesterol acts as a buffer for membrane fluidity, ensuring the plasma membrane remains functional across a range of temperatures, rather than serving as a polar head group, forming pores, or covalently cross-linking phospholipids.
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