Explain how the structure of an antigen-binding site gives it specificity for a particular antigen, as shown in Fig. 6.1.
State the role of the hinge region of the antibody shown in Fig. 6.1.
Antibodies can attach to membrane receptors on cells of the immune system, such as macrophages. Suggest one advantage of antibodies binding to receptors on macrophages.
It is estimated that the immune system of each person can produce enough antibodies to bind to over $10^{12}$ different antigens. When plasma cells make antibody molecules they combine the polypeptides produced by the expression of genes for heavy chains and the genes for light chains. Research has shown that producing this very large number of antibodies is only possible by altering the primary transcripts of the genes that code for heavy chains and the genes that code for light chains. Suggest how this modification of the primary transcripts occurs in plasma cells.