Question: 143. Identify the statement that is NOT correct.
(1) Each antibody has two light and two heavy chains.
(2) The heavy and light chains are held together by disulfide bonds.
(3) Antigen binding site is located at C-terminal region of antibody molecules.
(4) Constant region of heavy and light chains are located at C-terminus of antibody molecules.
Answer: Option (3)
Explanation:
An antibody molecule consists of two heavy chains and two light chains, which are joined by disulfide bonds, so statements (1) and (2) are correct.
The constant (C) region of both heavy and light chains is located toward the C-terminus, making statement (4) correct.
The antigen-binding site, however, is formed by the variable (V) regions of the heavy and light chains, located at the N-terminal end, not the C-terminal end.
Therefore, statement (3) is NOT correct.