: The two arms that bind to antigens.

: Forms the base and lower parts of the arms. It determines the antibody's class and how it interacts with other parts of the immune system. Fab and Fc Fragments :

: Found at the tips of the "Y" arms, this region determines the antibody's specificity . It contains the paratope , which binds to a specific part of an antigen called an epitope .

: The tail of the "Y" that communicates with immune cells to trigger a response. 2. The Five Classes of Antibodies Antibody Structure | Request PDF - ResearchGate

: It consists of two identical heavy chains (~50 kDa each) and two identical light chains (~25 kDa each), held together by disulfide bonds.