Question

In typical structure of the plasma membrane

a) The lipids are amphipathic.
b) Proteins are arranged asymmetrically and shows flip flop movement.
c) Extrinsic proteins are abundant towards cytoplasmic face.

• A. All are correct
• B. a, b is correct
• C. b, c is correct
• D. a, c is correct

Answer 1

The correct option is A All are correct

• All of the lipid molecules in cell membranes are amphipathic (or amphiphilic)—that is, they have a hydrophilic (“water-loving”) or polar end and a hydrophobic (“water-fearing”) or nonpolar end. The most abundant membrane lipids are the phospholipids. These have a polar head group and two hydrophobic hydrocarbon tails.
• Transverse diffusion or flip-flop involves the movement of a lipid or protein from one membrane surface to the other. Unlike lateral diffusion, transverse diffusion is a fairly slow process due to the fact that a relatively significant amount of energy is required for flip-flopping to occur.
• The reason the cell membrane is asymmetric is that when the proteins are synthesized by the preexisting membranes, they are inserted into the membrane in an asymmetric manner. The asymmetry of the cell membrane allows the membrane to be rigid and allows the cell to have a different intracellular environment from the existing extracellular environment. Additionally, the cell membrane's phospholipids are distributed asymmetrically across the lipid bilayer, in a phenomenon called membrane phospholipid asymmetry.
• The internal proteins are called intrinsic or integral proteins while the external ones are known as extrinsic or peripheral proteins. The amount and types of extrinsic proteins are different on the two sides. They are more abundant on the inner surface than on the outer surface,
  

So, the correct answer is 'all are correct'.