Final answer:
Antibodies show a variety of constant domains due to genetic recombination, but these domains are consistent within antibody classes. The constant domain determines the type and function of the antibody, whereas the variable domain determines binding specificity, allowing the immune system to target specific pathogens efficiently.
Step-by-step explanation:
Antibody Diversity and Constant Domains
The variety of constant domains in antibodies isolated from the same individual can be attributed to genetic recombination that leads to antibody diversity. Antibodies are comprised of variable and constant regions, with the variable domain forming the antigen-binding site. The constant domain, however, does not dictate the antibody's binding specificity, but instead determines its class and effector functions. While the light and heavy chain variable domains undergo genetic recombination to create a diverse repertoire of antigen-binding sites, the numbers of repeated constant domains in antibodies are the same for all antibodies within a specific class (e.g., IgM, IgG, IgA, IgD, IgE). This classification means that antibodies can have identical constant domains but different variable domains, allowing for specific pathogen targeting.
The human body's ability to produce a vast array of more than 1012 different antibody molecules from less than 50,000 genes showcases the efficiency and effectiveness of the immune system. This is due to the immense diversity generated by the unique combinations of variable domain gene segments and somatic hypermutation, which augments the fine specificity for antigen binding, without the need for each antibody to be encoded by a separate gene.