Question

In Singer and Nicolson's model, the extrinsic proteins are

• A. Tightly associated with intrinsic proteins but can be easily separated
• B. Loosely associated with intrinsic proteins and can be easily separated
• C. Loosely associated with intrinsic proteins but cannot be easily separated
• D. Tightly associated with intrinsic proteins and cannot be easily separated

Answer 1

The correct option is B Loosely associated with intrinsic proteins and can be easily separated

• The fluid mosaic model of the biomembrane or cell membrane was proposed by SJ Singer and GL Nicolson in the year 1972.
  
• According to this model, the protein molecules are embedded in the lipid bilayer.
• The membrane proteins are of two type-

1. Intrinsic proteins are found embedded in the cell membrane and are also called integral proteins.
2. Extrinsic proteins are present outside of the cell membrane and are bound to it by weak molecular forces (ionic or hydrogen bonds), they are soluble in aqueous solutions thus, they are easily separated.

• So, the correct answer is 'Loosely associated with intrinsic proteins and can be easily separated'.