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?

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

Answer 1

Answer: (C)

While lipids can rarely flip-flop, proteins cannot.

The movement of a molecule from one surface of the biological membrane to the other is called as the flip-flop movement or transverse diffusion.

In biological membrane, there are lipid transporter proteins named flippases, which are responsible for the movements of lipids.

The biological membranes have central hydrophobic region. The proteins do not show flip-flop movement due to their extensive polar nature which is unfavorable in the hydrophobic core of the membrane.