Question

Cholesterol molecules disrupt the close packing of fatty acyl chains and interfere with their mobility. The presence of cholesterol tends to ________ and ________ fluidity.

Answer 1

Cholesterol affects membrane fluidity by reducing and regulating it, acting as a buffer against temperature changes to maintain consistent cell membrane function.

Step-by-step explanation:

The presence of cholesterol in the plasma membrane tends to reduce and regulate fluidity. Cholesterol molecules insert themselves between the fatty acid tails of phospholipids, filling the spaces and reducing lateral mobility. This action stiffens the plasma membrane by decreasing fluidity, which also affects membrane permeability to certain ions. However, cholesterol also functions as a buffer against temperature changes; it dampens the effects of temperature on the membrane, preventing lower temperatures from inhibiting fluidity and higher temperatures from excessively increasing it. This means cholesterol helps maintain a consistent range of membrane fluidity critical for cellular function, which is especially relevant in varying environmental temperatures.