Multiple Choice
In the context of the lipid bilayer, the primary structural components of the cell (plasma) membrane are:
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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 cell membrane?
A
It forms aqueous channels that allow ions and polar molecules to diffuse freely across the membrane.
B
It buffers membrane fluidity by restricting phospholipid movement at high temperatures and preventing tight packing at low temperatures, helping stabilize the bilayer.
C
It covalently cross-links phospholipids to make the membrane permanently rigid and impermeable.
D
It serves as the main energy-storage molecule in the membrane by forming triacylglycerols within the bilayer.
Verified step by step guidance1
Understand the structure of the lipid bilayer, which is primarily composed of phospholipids arranged with hydrophilic heads facing outward and hydrophobic tails inward, creating a semi-permeable membrane.
Recognize that membrane fluidity is crucial for proper cell function, allowing proteins and lipids to move laterally within the bilayer and enabling membrane flexibility.
Identify cholesterol as a lipid molecule interspersed among phospholipids in the bilayer, influencing membrane properties.
Know that cholesterol's role is to modulate membrane fluidity: at high temperatures, it restricts excessive phospholipid movement to prevent the membrane from becoming too fluid; at low temperatures, it prevents phospholipids from packing too tightly, which would make the membrane too rigid.
Conclude that cholesterol acts as a buffer for membrane fluidity, stabilizing the bilayer across temperature changes, rather than forming channels, cross-linking lipids, or serving as an energy storage molecule.
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