Question

Begin by describing the basic structure of cholesterol. Then indicate how this crucial lipid is positioned within a lipid bilayer. Explain the effect upon the Tm of the membrane if the cholesterol concentration was increased.

Answer 1

Cholesterol is a steroid molecule, having four hydrocarbon rings. To one end of the steroid, hydrocarbon chain is attached, and to the other end, hgydroxyl group is attached. Because of the presence of steroid and alcoholic group, it is known as sterol.

It is preseneted in between the phospholipid bi layers in the cell membrane. The hydroxyl group of cholesterol aligns with the polar hear groups of bilayers.

Cholesterol acts as regulator in the fluidity of the cell membrane. At low temperatures, it intercalates and prevents the clustering of phospholipids. At high temperatures, it raises the melting point of the membrane and stabilizes it.

Hence the cholesterol atcs as buffer for the membrane fluidity.

A high concentration of cholesterol increases intermolecular forces and decreases the fluidity by decreasing the melting temperature (Tm)