Final answer:
Antibodies are composed of two heavy chains on the inside and two light chains on the outside of a Y-shaped structure, held together by disulfide bonds. The antibody structure includes variable domains for antigen binding and constant domains forming the base.
Step-by-step explanation:
Antibodies consist of two types of polypeptide chains:
- Two heavy chains—located on the inside of the Y-shaped molecule
- Two light chains—located on the outside of the Y-shaped molecule
The chains are held together by disulfide bonds.
Each antibody molecule is made up of four polypeptides: two identical large peptide units known as heavy chains that form the base of the Y-shaped structure and two identical small peptide units known as light chains flanking the heavy chains. Disulfide bonds, which are covalent bonds between cysteine amino acids within the antibody molecule, connect the polypeptides. Furthermore, the antigen-binding sites at the ends of the Y are formed by variable domains, while the base of the antibody consists of constant domains.