Question

An epitope associates with which part of an antigen receptor or antibody?

(A) the tail

(B) the heavy-chain constant regions only

(C) variable regions of a heavy chain and light chain combined

(D) the light-chain constant regions only

Short answer

(A) The option “the tail” is false.

(B) The option “the heavy-chain constant regions only” is false.

(C) The option “variable regions of a heavy chain and light chain combined” is true.

(D) The option “light-chain constant regions only” is false.

Step-by-step solution

Adaptive immunity

The type of immunity that activates after exposure to an antigen is called adaptive immunity. Vaccination also activates the adaptive immune system. This type of immune response occurs much longer than the innate response.

However, it is specific and has the memory to recognize the pathogens and produce antibodies.

Explanation of option (A)

The tail of the antigen receptor is used to communicate with the other parts of the immune system.

Therefore, the epitope does not attach to the tail.

Thus, the given statement is false.

Explanation of option (B)

An epitope is the part of an antigen that interacts with both constant and variable regions of light and heavy chains of the antigen receptors.

Therefore, the heavy chain alone does not attach to the epitopes.

Thus, the given statement is false.

Explanation of option (C)

The antigen receptors or antibodies contain heavy chains and light chains. These are identical and made up of four polypeptide chains. Each chain includes both constant and variable regions. Antibodies reversibly attach to the epitope, which helps to destroy the antigen.

Therefore, both heavy and light chains participate in attachment with the epitope of an antigen.

Thus, the given statement is true.

Explanation of option (D)

The light and heavy chain both interact with the epitope associates.

Therefore, variable regions of the light chain alone do not combine with the epitope.

Thus, the given statement is false.