Final answer:
IgG has two antigen-binding sites with high affinity for antigens, while TCR has one antigen-binding site for processed antigens presented by MHC molecules.
Step-by-step explanation:
IgG possesses two binding sites for antigens (Ag); TCR possesses one binding site for antigens. IgG antibodies have a Y-shaped structure with two antigen-binding sites, ensuring high affinity for their specific antigens, and are involved in various immune mechanisms including agglutination of pathogens.
On the other hand, the T-cell receptor (TCR) is part of the antigen receptors on T cells and, while sharing some common structural elements with immunoglobulins, has a simpler configuration with a single antigen-binding site, which recognizes processed antigens in conjunction with MHC I or MHC II molecules.
IgG possesses two binding sites for Ag; TCR possesses one binding site for Ag.