Final answer:
Antibodies are composed of two identical heavy chains and two identical light chains, forming a Y-shaped structure. They contain one of two types of light chains, kappa or lambda, and have different heavy chains that determine the class of the immunoglobulin. The antigen-binding site is formed by both the heavy and light chains, with the Fc region enabling interactions with immune effector cells.
Step-by-step explanation:
Antibodies, also known as immunoglobulins, are composed of two types of polypeptide chains: heavy chains and light chains. Antibodies consist of two identical heavy chains and two identical light chains, forming a Y-shaped structure. There are two types of light chains, kappa (κ) and lambda (λ), but an antibody will only contain one type, not both. With regards to heavy chains, there are five different types, each corresponding to a different type of immunoglobulin: gamma (y), alpha (a), mu (μ), epsilon (ε), and delta (δ).
The antigen-binding sites of an antibody are formed by both the heavy and light chains, and the constant domains provide the structural base of the antibody. The variable domains of the heavy (VH) and light (VL) chains are responsible for antigen recognition. The Fc region of the antibody, important for the interaction with effector cells, is formed by the heavy chains linked usually through disulfide bonds.