Q.Why is an antibody molecule represented as H2 L2?

An antibody (immunoglobulin) is a Y-shaped protein built from four polypeptide chains: two identical light chains (~25,000 Da) and two identical, larger heavy chains (~50,000 Da), linked by disulphide bonds — one light chain per heavy chain, and the two heavy chains joined to each other — giving the formula H2L2. A flexible hinge region near the middle of the heavy chains lets the molecule's two arms move independently. Each chain has a variable (V) region, which differs between antibodies to match different antigens, and a constant (C) region, which is essentially the same across antibodies of a given class; on each arm, the heavy- and …