Question

cholesterol is found embedded within both sides of the phospholipid bilayer of the cell membrane. which of the following occurs as the amount of cholesterol decreases within the cell membrane? a.) the cell membrane flexibility remains unchanged. b.) the cell membrane rigidity remains unchanged. c.) the cell membrane becomes more flexible and less rigid. d.) the cell membrane becomes less flexible and more rigid.

Explanation:

Cholesterol in the cell membrane acts as a "buffer" for membrane fluidity. At high temperatures, it makes the membrane less fluid (more rigid), and at low temperatures, it makes the membrane more fluid (less rigid). When the amount of cholesterol decreases, the membrane loses this buffering effect. At normal physiological temperatures (which are relatively high compared to very low temperatures), without cholesterol's rigidifying effect, the membrane becomes less rigid. Also, without cholesterol's ability to prevent phospholipids from getting too close (which would make it rigid at low temps, but at normal temps, lack of cholesterol means phospholipids can move more freely in a way that increases flexibility). So the membrane becomes more flexible and less rigid.

Answer:

C. The cell membrane becomes more flexible and less rigid.