Q. 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 respects. In this regard, which of the following statements is incorrect?
A) Proteins in cell membranes can travel within the lipid bilayer
B) Proteins can remain confined within certain domains of the membrane
C) Proteins can also undergo flip-flop movements in the lipid bilayer
D) Many proteins remain completely embedded within the lipid bilayer
Explanation
[Solution from source] Membrane proteins can move sideways within the bilayer but practically never flip from one face to the other. Their hydrophilic parts cannot cross the hydrophobic core, and this is why membranes stay asymmetric. Lipids can flip-flop slowly; proteins do not. Answer (3).
Reviewed by Dr. Abubacker
Physics Educator & NEET/JEE Specialist
Ph.D. in Physics with 19+ years of teaching experience.