Final answer:
Ig light chains and T cell receptor alpha chains consist of both variable (V) and joining (J) segments. These contribute to the diversity of each chain, with B cells having over 106 different VJ combinations due to genetic recombination.
Step-by-step explanation:
Ig light chains and T cell receptor alpha chains have both variable (V) and joining (J) segments. In the structure of Ig light chains, the variable region is designated Vik and the constant region as Ck. For T cell receptor alpha chains, the variable (V) region domain is at the terminal end, which is responsible for antigen specificity. The joining (J) segment is included in the V region of the alpha chain and contributes to the diversity of the antigen receptor through genetic recombination. The constant (C) region follows the VJ segments and has less variation compared to the variable segment.
Each differentiated B cell has a unique variable chain due to the combination of V and J segments, facilitated by DNA recombinase during B cell development. This results in a vast diversity of possible VJ combinations, exceeding 106 different pairs. Similarly, T cell receptors exhibit diversity in their V regions, enabling the recognition of a wide array of antigens.