Question

What is the antigen binding site on the antibody?

Epitope

Variable region

Valence site

Hapten

Answer 1

Option 'a' (epitope) is correct

Justification: The binding site of antigen on the antibody is the epitope. The paratope is a part of antibody which recognizes an antigen and it contains heavy and light chains. Epitope is the part of an antigen to which an antibody is attached. So, option 'a' is correct.

Justification for incorrect options:

• Option 'b' is incorrect because the variable region contains amino acids and it gives specificity to antibody for binding an antigen. It also includes heavy and light chains.
• Option 'c' is incorrect because valence is the number of binding sites of antigen.
• Option 'd' is incorrect because hapten is a small molecule which stimulates the production of antibody molecules but, it is NOT the antigen binding site.

Thank you!