Question

Which of the following statements about antibodies is/are correct?

• A. Different antibody classes have different effector functions.
• B. Each antibody chain consists of an amino-terminal constant region and a carboxy-terminal variable region.
• C. Variable domains harbor complementarity-determining regions.
• D. All antibodies have the same half-life.

Hint:

Antibodies exhibit great diversity in their structures and functions. The variable region determines antigen specificity, while the constant region defines effector functions.

Answer 1

The Correct Option is A, C

- (A): Different antibody classes (IgG, IgA, IgM, etc.) do indeed have different effector functions. For example, IgG is involved in opsonization and neutralization, while IgE is associated with allergic responses. This makes statement (A) correct.
- (B): This statement is incorrect. Each antibody chain consists of a variable region (not constant) at the amino-terminal end and a constant region at the carboxy-terminal end. Thus, statement (B) is incorrect.
- (C): Variable domains in antibodies contain complementarity-determining regions (CDRs), which are regions of the variable domain that directly interact with the antigen. These regions are critical for the antibody’s specificity. Hence, statement (C) is correct.
- (D): Antibody half-life varies depending on the class of the antibody. For example, IgG has a longer half-life compared to IgM, so statement (D) is incorrect.
Thus, the correct answers are (A) and (C).