[Campbell Biology P.177] How does cholesterol affect membrane fluidity in animal cells? | Practice Question

How does cholesterol affect membrane fluidity in animal cells?

  • A: It always increases fluidity, acting as a lubricant.
  • B: It always decreases fluidity, making the membrane more rigid.
  • C: It decreases fluidity at moderate to high temperatures but hinders solidification at low temperatures.
  • D: It increases fluidity at high temperatures and promotes solidification at low temperatures.

Explanation

Cholesterol acts as a 'fluidity buffer'. At relatively high temperatures like human body temperature , it makes the membrane less fluid by restraining phospholipid movement. However, at low temperatures, it hinders the close packing of phospholipids, thereby lowering the temperature required for the membrane to solidify.