Final answer:
B cell development involves the rearrangement of the heavy chain first, followed by the light chain, contrary to the question's premise that light chain rearrangement occurs before the heavy chain. The heavy chain includes V, D, and J segments, while the light chain consists of V and J segments, and DNA recombinase mediates the rearrangement.
Step-by-step explanation:
The correct answer to the question is b) False. In B cell development, the heavy chain rearrangement occurs before the light chain. Specifically, the variable region of the BCR (B Cell Receptor) heavy chain, which is composed of V (variable), D (diversity), and J (joining) segments, undergoes recombination first. This is followed by the rearrangement of the light chain, which includes V and J segments.
During the maturation of germ-line B cells, an enzyme known as DNA recombinase plays a crucial role in randomly excising V, D, and J segments for the heavy chain and V and J segments for the light chain. This rearrangement is essential for creating the immense diversity of antibodies, each with a unique variable region capable of binding different antigens. After DNA rearrangement, RNA processing, transcription, and translation occur, leading to the production of a mature antibody. Each differentiated B cell will typically possess a unique variable chain, critical for the specific recognition and binding to an antigen.