Final answer:
B cells undergo gene rearrangement in their Ig genes during their life cycle, leading to the production of diverse immunoglobulin antibody molecules.
Step-by-step explanation:
B cells undergo changes in Ig genes during their life cycle through the process of gene rearrangement. These genes contain variable (V), joining (J), and diversity (D) regions that recombine to create diverse immunoglobulin antibody molecules. This rearrangement occurs during the maturation of stem cells in the bone marrow. The resulting antibodies can recognize, bind, and eliminate specific antigens.
Figure 42.22 (a) illustrates how DNA recombinase randomly excises V and J segments from the light chain gene, leading to further gene rearrangement at the mRNA level. As a result, each antibody has a unique variable region capable of binding a different antigen.
The diversity of antibodies is crucial for the immune system to respond to a wide range of antigens. Rearrangement of gene segments encoding antibody polypeptides occurs at the DNA level, resulting in an enormous diversity of antibody molecules.