Question 4
One role of cholesterol in membranes is:
Options:
A) Cell recognition
B) Cell-signaling receptor
C) Controlling fluidity
D) Hydrophilic channel
Answer:
Correct Answer: C) Controlling fluidity
Explanation:
Hydrophilic channels are formed by channel proteins to allow polar substances to cross the membrane. Cholesterol does not form channels.
Role of Cholesterol in Membranes
Cholesterol is an essential component of cell membranes, especially in animal cells.
It modulates membrane fluidity by preventing the fatty acid chains in phospholipids from packing too closely together.
At low temperatures, cholesterol prevents the membrane from becoming too rigid by increasing fluidity.
At high temperatures, it stabilizes the membrane by reducing excessive fluidity, helping maintain structural integrity.
Why Other Options Are Incorrect
A) Cell Recognition
Cell recognition typically involves glycoproteins and glycolipids, not cholesterol.
B) Cell-Signaling Receptor
Cholesterol is not involved directly in cell signaling; receptors (such as proteins) fulfill this function.
D) Hydrophilic Channel
Hydrophilic channels are formed by channel proteins to allow polar substances to cross the membrane. Cholesterol does not form channels.