Answer :
Proteins called antibodies defend you when your body comes into contact with an unwelcome chemical. Antibodies, which are made by your immune system, bind to these foreign chemicals and drive them out of your body.
An antibody molecule has two identical antigen-binding sites and may thus attach to two identical structures at once since each immunoglobulin molecule has two identical heavy chains and two identical light chains. Immunoglobulins, a class of proteins relevant to the immune system, are antibodies. Each antibody is made up of four polypeptides, linked into a "Y" shape by two heavy chains and two light chains. Varied antibodies have very different "Y" tips' amino acid sequences.The Fab (fragment, antigen binding) region is the name given to this area of the antibody. It is made up of one constant and one variable domain from each of the antibody's heavy and light chains.
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