Question

Keeping in view the fluid mosaic model for the structure of cell membrane, which one of the following statements is correct with respect to the movement of lipids and proteins from one lipid monolayer to the other (described as flip-flop movement)?

• A. While proteins can flip-flop, lipids can not
• B. Neither lipids, nor proteins can flip-flop
• C. Both lipids and proteins can flip-flop
• D. While lipids can rarely flip-flop, proteins cannot

Answer 1

The correct option is D While lipids can rarely flip-flop, proteins cannot

Flip flop movement is also known as transverse diffusion. It involves the transport of a lipid or protein from one membrane surface to the other. Transverse diffusion is a fairly slow process as it requires a huge amount of energy for flip-flopping. Most large proteins do not flip-flop due to their extensive polar regions, which are unfavorable in the hydrophobic core of a membrane bilayer. This allows the asymmetry of membranes to be retained for long periods, which is an important aspect of cell regulation.

Hence the right answer is D.