Question

Mammalian cells cultured at low temperature (25 to 30 °C) lead to an increased sterol content in the membrane. Elevated sterols in the membrane result in

• A. ( an enhancement in membrane fluidity.)
• B. ( stabilization of membrane proteins.)
• C. ( an increase in membrane permeability to water.)
• D. ( a decrease in membrane fluidity.)

Hint:

Sterols act as "fluidity buffers" in membranes, increasing fluidity at low temperatures and decreasing it at high temperatures.

Answer 1

The Correct Option is A

Step 1: Role of sterols in membranes. Sterols, such as cholesterol in mammalian cells, are critical components of cellular membranes. They influence membrane properties like fluidity and stability.
Step 2: Effects of low temperature. At low temperatures, membrane phospholipids tend to become more ordered and less fluid. To counteract this, cells increase sterol content in the membrane, which prevents tight packing of the fatty acid chains and enhances membrane fluidity.
Step 3: Evaluating options. - (A) Correct: Increased sterol content enhances membrane fluidity at low temperatures. - (B) Incorrect: While sterols stabilize the bilayer, the primary effect here is fluidity enhancement. - (C) Incorrect: Sterols reduce membrane permeability to small molecules like water, not increase it. - (D) Incorrect: Elevated sterols do not decrease membrane fluidity; they enhance it at low temperatures.
Step 4: Conclusion. The correct option is (A), as sterols enhance membrane fluidity to maintain proper membrane function at low temperatures.