Question

Which of the following factors does not affect membrane permeability?

Answer 1

Answer:

a. The polarity of membrane phospholipids.

Explanation:

Phospholipids are the amphipathic lipids with polar heads and non-polar tails. The non-polar tails of two lipid layers form the core of the membrane while their heads are oriented towards both of the faces of the membrane. The polarity of the phospholipids does not affect the transport of substances. If a membrane has more of the saturated phospholipid tails in its core, the tight packing of the tails makes the membrane less permeable for large and polar substances.

On the other hand, a membrane with a greater proportion of unsaturated hydrocarbon tails in its core is more permeable. Cholesterol is also an amphipathic sterol and moderates the fluidity of membrane and thereby affects its permeability. A more fluid membrane is more permeable than a more solid membrane. Temperature affects the membrane polarity by affecting the membrane fluidity.