Antibody specificity is determined by the amino acid sequence within the:

Ans. C. Variable regionAntibody specificity is dictated by the sequence of amino acids within the variable regions of the light and heavy chains.a. The Fc region is a site for antibody docking to effector cells and does not play a role in antigen binding.b. The constant region has a similar structure in antibodies of widely divergent specificity and, therefore, does not dictate specificity.c. Fc receptors are sites on immune effector cells that interact with the Fc region of the antibody molecule and do not define an antibody's specificity.d. The J chain is a unique portion of secreted IgA molecules that allows the molecule to move from the circulation through mucous membranes.