Solution:

• Antibodies are glycoproteins which are highly specific to antigens. 
• They are also known as immunoglobulins (Igs). 
• They have a ‘Y’ shaped structure. 
• It consists of four polypeptide chains, two heavy (H) chains and two light (L) chains. 
• Four polypeptide chains are held together by disulfide bonds to form a ‘Y’ shaped structure. 
• Region holding arms and stem of antibody is termed as hinge. 
• Each chain of the antibody includes two distinct regions, the variable region and the constant region. 
• Variable regions constitute the antigen-binding site (paratope). 
• This part of the antibody recognizes and binds to the specific antigen forming an antigen-antibody complex.