Multiple Choice
In animal cells, which molecule is primarily responsible for strengthening the plasma membrane by modulating its fluidity and stability?
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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 forms aqueous pores that allow ions to diffuse freely across the membrane without transport proteins.
B
It covalently cross-links phospholipid tails to permanently rigidify the membrane.
C
It acts as the main energy source for membrane-associated enzymes by being rapidly oxidized in the bilayer.
D
It buffers membrane fluidity by reducing permeability and preventing extreme changes in fluidity across temperatures.
Verified step by step guidance1
Understand the structure of the plasma membrane, which is primarily composed of a phospholipid bilayer with embedded proteins and cholesterol molecules.
Recognize that membrane fluidity is crucial for proper membrane function, affecting protein mobility, permeability, and cell signaling.
Identify cholesterol's role as a modulator of membrane fluidity: it inserts between phospholipid tails and interacts with them.
Explain how cholesterol reduces membrane permeability by filling spaces between phospholipids, making the membrane less permeable to small molecules.
Describe how cholesterol prevents extreme changes in fluidity by restraining phospholipid movement at high temperatures and preventing tight packing at low temperatures, thus buffering membrane fluidity.
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