Question

Which of the following is true about the cholesterol associated with membranes?

1) It makes the cell membrane fluid at room temperature.
2) It interferes with the movements of the fatty acid tails of the phospholipids.
3) It is oriented with the small hydroxyl group embedded in the lipid bilayer and the remainder of the molecule toward the membrane surface.
4) All of these statements are correct.

Answer 1

Cholesterol helps maintain the fluidity of cell membranes and reduces membrane permeability to some ions. It is oriented with the small hydroxyl group embedded in the lipid bilayer and the rest of the molecule toward the membrane surface.

Step-by-step explanation:

Cholesterol is an important component of cell membranes and has several functions. It helps maintain the fluidity of the membrane by filling the spaces between fatty acids in the hydrophobic interior of the membrane. This reduces the lateral mobility of phospholipid and protein components, decreasing membrane permeability to some ions and making the membrane less fluid. Additionally, cholesterol is oriented with the hydroxyl group embedded in the lipid bilayer and the rest of the molecule toward the membrane surface.