Describe the structure of antibody.

Explanation

(1) Antibodies are highly specific to specific antigens. They are glycoprotein called immunoglobulins (Igs).
(2) They are produced by plasma cells. Plasma cells are in turn fonned by B-lyinphocytes.
(3) About 2000 molecules of antibodies are formed per second by the plasma cells.
(4) Antibody is a 'Y'-shaped molecule. It has of four polypeptide chains, two heavy or H chains and two light or L chains.
(5) Disulfide bonds (- s-s-) hold the polypeptide chains together to form a 'Y'-shaped structure.
(6) The region holding arms and stem of antibody is termed as hinge. Each chain of the antibody has two distinct regions, the variable region and the constant region.
(7) Variable regions have a paratope which is an antigen-binding site. This part of antibody recognizes and binds to the specific antigen forming an antigen-antibody complex.
(8) Antibodies are called bivalent as they carry two antigen binding sites.