The correct answer is this question is option B - Composed of heavy and light polypeptide chains
Antibodies are glycoproteins made by B cell (B lymphocytes). They bind to specific foreign bodies such as antigens.
Antibodies are also known as immunoglobulin. They are composed of both heavy and light polypeptide chains. They consist of 2 heavy chains and 2 light chains arranged as a Y shaped molecule.
There are 5 isotypes of antibodies. They are found in different locations and they serve different purposes. These isotypes are: IgA, IgD, IgE, IgG and IgM.
IgA is expressed in mucosal surfaces and it forms dimmer after secretion. It is found in the mucosal lining of respiratory tract and the mucosal lining of the digestive system.
IgD – expressed on surface of immature B cells
IgE – Seen in allergy
IgG – opsonisation and neutralizing activates
IgM - first antibody produced upon invasion by antigen.
Antibodies react to particular characteristics of different antigens, binding them to the top ends of their Y formation. Once the antibody and antigen combine, the antibodies deactivate the antigen or lead it to macrophages, which is a kind of white blood cell. The macrophages ingest and destroy it.
The antibody is a large Y shaped protein produced mainly by plasma cells. Polypeptide chains are a chain of amino acids joined together through peptide bonds. The antibodies are composed of heavy light polypeptide chains. There are three binding sites per antibody monomer.