Question

Some regions of the plasma membrane, called lipid rafts, have a higher concentration of cholesterol molecules. As a result, these lipid rafts

A) are more fluid than the surrounding membrane.
B) are more rigid than the surrounding membrane.
C) are able to flip from inside to outside.
D) detach from the plasma membrane and clog arteries.
E) have higher rates of lateral diffusion of lipids and proteins into and out of the lipid rafts.

Answer 1

Lipid rafts have a higher concentration of cholesterol molecules which makes them more rigid compared to the surrounding membrane.

Step-by-step explanation:

Lipid rafts are specialized regions in the plasma membrane that have a higher concentration of cholesterol molecules, which affects their physical properties. The presence of cholesterol tends to fill the spaces between the fatty acids in the phospholipid bilayer, thereby reducing the lateral mobility of both proteins and lipids in those regions. As a result, the membrane becomes more rigid and less fluid, which is essential for the functioning of these regions. Therefore, the right answer is that the lipid rafts B) are more rigid than the surrounding membrane.

In summary, cholesterol plays a significant role in modulating the fluidity of the membrane. In lipid rafts, the higher concentration of cholesterol molecules decreases their fluidity, increases rigidity, and allows these regions to serve as platforms for cellular processes. This modulation is critical for the proper functioning of the plasma membrane and the organization of membrane-associated proteins.