Question

Of the following statements about antibodies and antigens ,choose the correct set
I.An antibody consists of four identical light (L) chains and two idntical heavy (H) chains
II.The stem of Y of antibody is called Fab fragment
III.The stem of antibody lower parts of its arms constitute constant (C) region
IV.Portion of antigen to which an antibody binds is called epitope

• A. II and IV
• B. I and III
• C. III and IV
• D. I and II

Answer 1

The correct option is C III and IV

• An antibody is also known as an immunoglobulin (Ig), is a large, Y-shaped protein produced mainly by plasma cells that are used by the immune system to neutralize pathogens such as pathogenic bacteria and viruses. The fragment crystallizable region or constant region (Fc region) is the tail region of an antibody that interacts with cell surface receptors called Fc receptors and some proteins of the complement system.
• An epitope, also known as the antigenic determinant, is the part of an antigen that is recognized by the immune system, specifically by antibodies, B cells, or T cells. For example, the epitope is the specific piece of the antigen to which an antibody binds.
• Hence, the correct set about antibodies and antigens are The stem of antibody lower parts of its arms constitute constant (C) region and Portion of antigen to which an antibody binds is called epitope.
• So, the correct answer is 'III and IV'.