Question

In a lipid bilayer, which behaves like a two-dimensional fluid, lipids rapidly

diffuse:
A. (A) within the plane of one monolayer in the bilayer.
B. (B) back and forth from one monolayer to the other in the bilayer.
C. Both A and B
D. Neither A nor B

Answer 1

Lipids in a lipid bilayer diffuse rapidly within the plane of one monolayer, making A the correct choice. Flip-flop diffusion between monolayers is less common due to energy constraints.

Step-by-step explanation:

In a lipid bilayer, which exhibits properties akin to a two-dimensional fluid, lipids rapidly diffuse within the plane of one monolayer in the bilayer. Thus, the correct answer is A: within the plane of one monolayer in the bilayer. This process is an essential aspect of the bilayer's dynamic nature, allowing the membrane to maintain its integrity while enabling various cellular processes. However, the movement of lipids from one monolayer to the other, known as flip-flop, occurs much less frequently due to the energy barrier associated with moving the hydrophilic head through the hydrophobic core of the membrane.