<span>It
is important that antibodies have a symmetrical quaternary structure to create
two identical binding sites for antigens. An antibody is a relatively large
protein having a Y-shape. Plasma cells produce antibodies which are then used
by the immune system to fight off pathogens (e.g. bacteria and virus). The antibody
is able to recognize the antigen of the pathogen. It binds with it either to
neutralize it directly or “tag” the microbe for future attack by other parts of
the immune system. </span>
