Write short notes on Immunoglobulins.

Explanation

Antibodies(Immunoglobulins): Whenever pathogens enter our body, the B.-lymphocytes produce an army of proteins called -antibodies to fight with them:-They are highly specialized for binding with specific antigens, The part of an antibody that recognizes an antigen is called the paratope (antigen binding site). Based on their mobility, antibodies are of two types, namely circulating or free antibodies and surface antibodies. The circulating or free antibodies are present in the body fluids whereas the surface antibodies are present on the surface of the mature B-cells as well as the memory cells.
Structure: The basic structure of an antibody was proposed by Rodney Porter. It is a Y shaped molecule with four polypeptide chains of which two are long, identical heavy chains (H) and two are small, identical light chains (L). Hence, an antibody is represented as `H_2L_2`. The two chains are linked by disulphide - bonds. One end of the antibody molecule is called `F_(ab)` end (Fragmentantigen binding) and the other end is called `F_(c)` end (Fragment - crystallizable or Fragment - cell binding). Based on. the structure, the antibodies are of five types, namely IgD, IgE, IgG, IgA and IgM.