The Portions of an Antigen to Which Antibodies Bind Are

Question

The portions of an antigen to which antibodies bind are the
A) active sites.
B) reactive sites.
C) antigenic determinant sites.
D) antibody active sites.
E) antigen activation segments.

Accepted Answer

The portions of an antigen to which antibodies bind are called antigenic determinant sites or epitopes. These are specific regions on the surface of antigens that are recognized by antibodies through their complementary specificity. The term "active sites" refers to regions on enzymes where substrates bind, while "antibody active sites" is not a commonly used term in immunology. "Reactive sites" and "antigen activation segments" are not accurate descriptions of the sites on antigens that bind to antibodies.