Question

Which among the following components of IgD would be made up of only the constant region?

• A. Fab
• B. Fc
• C. Antigen binding site
• D. F(ab)2

Answer 1

The correct option is B Fc

Antibodies are protein molecules called immunoglobulins. B-cells are differentiated into plasma cells, and these plasma cells in response to the stimulation of antigenic molecules produce antibodies.

All antibodies have the same basic structure, consisting of four polypeptide chains - two identical heavy chains and two identical light chains.

Different functions are carried out by different parts of the antibody. Two main parts are Fragment antigen-binding (Fab fragment) and Fragment crystallization (Fc region). The two variable N-terminal fragments of heavy and light chains where the antigen binds are called the Fab region and the C-terminal tail of the heavy chain is called the Fc region.

In F(ab)2 fragments (Fab+Fab), both the Fab fragments of an antibody are connected together by disulphide bonds, as seen in the pepsin digested antibody.

Antigen binding site, Fab and F(ab)2 has a combination of both heavy and light chains and only Fc region contains the constant region of the heavy chain