What is a role of cholesterol in cell membranes?

• A. It protects the cell from damage
• B. It increases protein synthesis
• C. It reduces membrane stability
• D. It is the primary energy source

Answer: (A)

Cholesterol in membranes acts to keep the lipid bilayer stable and properly fluid. By fitting between phospholipid molecules, it prevents the membrane from becoming too fluid at higher temps and from becoming too rigid at lower temps, which helps maintain the barrier function. This stabilization also means the membrane is less leaky and more resistant to physical or environmental damage, so the cell is better protected from damage. Cholesterol isn’t involved in making proteins, nor is it a source of energy, and it doesn’t decrease membrane stability—in fact, it reinforces it—so those options don’t describe its role.