Question

According to widely accepted fluid mosaic model, cell membranes are semi-fluid, where lipids and integral proteins can diffuse randomly. In recent years, this model has been modified in several represents. In this regard, which of the following statement is incorrect?

• A. Proteins in cell membranes can travel within the lipid bilayer.
• B. Proteins can also undergo flip-flop movements in the lipid bilayer.
• C. Proteins can remain confined within certain domains of the membrane.
• D. Many proteins remain completely embedded within the bilayer.

Answer 1

The correct option is B Proteins can also undergo flip-flop movements in the lipid bilayer.

Transverse diffusion or flip-flop involves the transfer of proteins or lipids from one surface to the other. It is a slow process and it requires lot of energy to flip-flop the proteins. Larger proteins do not flip-flop due to their extensive polar regions. The highlights of the model include, the lateral diffusion, control of fluidity, melting temperature and presence of internal, external and transverse proteins.