Question

Identify ‘a’,’b’ and ‘c’ in the schematic diagram of an antibody given above and answer the questions.
(i) Write the chemical nature of an antibody.
(ii) Name the cells that produce antibodies in humans.
(iii) Mention the type of immune response provided by an antibody

Answer 1

a-paratope(antigen binding site)
b-heavy chain(peptide chain)
c-disulphide bridges

i)Each antibody consists of four polypeptides– two heavy chains and two light chains (Formula:- H2L2) joined to form a "Y" shaped molecule. The amino acid sequence in the tips of the "Y" varies greatly among different antibodies. This variable region, composed of 110-130 amino acids, give the antibody its specificity for binding antigen.

ii) The B lymphocytes are responsible for producing an army of Y shaped proteins called antibodies in our response to pathogens into our blood to fight with them.

iii) Antibody provides Acquired Immunity to the body which is pathogen specific. It is characterized by memory. This means that our body when it encounters a pathogen for the first time produces a response called the 'Primary Response' which is of low intensity. Subsequent encounter with the same pathogen elicits a highly intensified 'Secondary or Anamnestic Response'. This is ascribed to the fact that our body appears to have memory of the first encounter.