Question

What is the role of the cholesterol in the cell membrane?
A. It functions in joining adjacent cells together
B. It functions in recognizing foreign cells
C. It increases the rate of transport of ions across the membrane
D. It stabilizes the cell membrane

Answer 1

Hint: The cell membrane is also known as the plasma membrane or the plasmalemma. It is a living membrane. The cell membrane is a selectively permeable membrane. Moreover, cholesterol is a kind of lipid found in the cell membrane.

Complete answer: The cell membrane is collectively made up of lipids and proteins. Therefore, they are known as lipoproteins. Cholesterol or lipid is found between the phospholipid bilayer in the cell membrane. If there is a temperature deviation, then it might cause the tails of the fatty acids to melt if the temperature goes higher and freeze if it drops. Due to this, the fluidity of the membrane will change. As the temperature will increase the phospholipid entities will tend to move away from each other. If the temperature goes down then the molecules will come closer to one another. Due to this, the ability of the membrane to transport the substances will be disrupted. But to prevent all of this the cholesterol is the stabilizing molecule. It prevents the extreme movement of the phospholipids during the temperature deviations. Thus, based on the above information, we can conclude that cholesterol stabilizes the cell membrane.
Hence, the correct answer is option (D).

Note: The trilamellar model of the cell membrane was proposed by Danielle and Davson. According to the trilamellar theory the structure of the cell membrane consists of bilayered phospholipids and globular proteins. The bilayer phospholipids are lined by the proteins on both sides of the membrane. The phospholipid molecules are made up of head and tail.