Multiple Choice
In cell biology, what is another name for 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 is the main component of the glycocalyx and provides most of the membrane’s carbohydrate-based cell recognition.
B
It buffers membrane fluidity by reducing excessive movement at high temperatures and preventing tight packing (solidification) at low temperatures.
C
It forms transmembrane channels that allow ions to diffuse directly through the hydrophobic core of the bilayer.
D
It covalently cross-links phospholipid tails to permanently rigidify the membrane under all conditions.
Verified step by step guidance1
Step 1: Understand the structure of the plasma membrane, which primarily consists of a phospholipid bilayer with embedded proteins and cholesterol molecules.
Step 2: Recognize that cholesterol is a lipid molecule interspersed among the phospholipids within the bilayer, influencing membrane properties.
Step 3: Recall that membrane fluidity is crucial for proper membrane function, allowing proteins to move and the membrane to be flexible under different temperatures.
Step 4: Know that cholesterol acts as a fluidity buffer by inserting itself between phospholipid tails, which prevents them from packing too tightly at low temperatures (avoiding solidification) and restricts excessive movement at high temperatures (reducing fluidity).
Step 5: Conclude that cholesterol's primary role is to maintain membrane stability and fluidity across temperature changes, rather than forming channels, cross-linking lipids, or being a carbohydrate component.
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