Question

Match List-I with List-II
List-I (Name of Immunoglobulin)
(A). IgG
(B). IgM
(C). IgA
(D). IgE
List-II (Corresponding Heavy chain)
(I). Alpha Heavy chain
(II). Epsilon Heavy chain
(III). Gamma Heavy chain
(IV). Mu Heavy chain
Choose the correct answer from the options given below:

• (A) - (I), (B) - (II), (C) - (III), (D) - (IV)
• (A) - (I), (B) - (II), (C) - (IV), (D) - (III)
• (A) - (III), (B) - (IV), (C) - (II), (D) - (I)
• (A) - (III), (B) - (IV), (C) - (I), (D) - (II)

Hint:

An easy way to remember immunoglobulin heavy chains is that the class name letter corresponds directly to the Greek letter of its heavy chain:
- IgG $\rightarrow$ Gamma ($\gamma$)
- IgM $\rightarrow$ Mu ($\mu$)
- IgA $\rightarrow$ Alpha ($\alpha$)
- IgE $\rightarrow$ Epsilon ($\epsilon$)
- IgD $\rightarrow$ Delta ($\delta$)

Answer 1

The Correct Option is D

Step 1: Understanding the Concept:
Immunoglobulins (antibodies) are heterodimeric glycoprotein complexes consisting of two heavy (H) chains and two light (L) chains.
The class (isotype) of an immunoglobulin is determined exclusively by the amino acid sequence of the constant region of its heavy chains.

Step 2: Detailed Explanation:
Let us match each immunoglobulin class with its designated heavy chain:
- (A) IgG: This is the most abundant immunoglobulin class in the serum. Its heavy chains are designated as gamma ($\gamma$) heavy chains (III).
- (B) IgM: This is the first antibody isotype secreted during a primary immune response, typically forming a pentamer. Its heavy chains are mu ($\mu$) heavy chains (IV).
- (C) IgA: This is the dominant antibody found in mucosal secretions (saliva, tears, colostrum). Its heavy chains are alpha ($\alpha$) heavy chains (I).
- (D) IgE: This class is involved in allergic reactions and defense against parasitic infections. Its heavy chains are epsilon ($\epsilon$) heavy chains (II).
Matching these gives: (A) - (III), (B) - (IV), (C) - (I), (D) - (II).

Step 3: Final Answer:
This sequence corresponds to option (D).