Question

IgG possesses _______ binding sites for antigen, and the T-cell receptor possesses _______ binding sites for antigen:

a. 2; 1
b. 1; 2
c. 2; 2
d. 2; 4
e. 1; 1

Answer 1

The direct answer is a. 2; 1, indicating that IgG has 2 binding sites and the T-cell receptor has 1. IgG is a Y-shaped antibody with two antigen-binding sites, while the T-cell receptor on T-cells has one site that recognizes peptides when presented by MHC molecules.

Step-by-step explanation:

The correct answer to the question is: IgG possesses 2 binding sites for antigen, and the T-cell receptor possesses 1 binding site for antigen. Therefore, the correct option is a. 2; 1.

IgG antibodies are Y-shaped molecules made up of two heavy chains and two light chains, creating a structure with two identical antigen-binding sites, allowing them to bind to two antigens simultaneously. On the other hand, the T-cell receptor (TCR), which is found on the surface of T-cells, usually has a single antigen-binding site. This site recognizes peptides presented by the Major Histocompatibility Complex (MHC) molecules on the surface of other cells. Unlike antibodies, T-cell receptors do not recognize free-floating antigens; instead, they recognize fragments of antigens as part of the MHC.