What is required to make B and T cells?

To understand why the correct answer is three segments of DNA that make a gene, it is essential to consider the process of lymphocyte development, specifically in B and T cells, which are crucial components of the adaptive immune system.

B and T cells undergo a process called V(D)J recombination, which is responsible for the generation of diverse antigen receptors. This recombination process involves the rearrangement of multiple gene segments: variable (V), diversity (D), and joining (J) segments of DNA. For B cells, particularly, immunoglobulin genes consist of a combination of these segments to create unique antibodies capable of binding specific antigens. Similarly, T cells rearrange their T cell receptor genes in a similar manner to specifically recognize antigens presented by other cells.

The production of these antigen receptors requires the integration of these three distinct segments of DNA, which work together to create a functional gene encoding for either an immunoglobulin or a T cell receptor. This multisegment approach is what enables the adaptive immune system to respond flexibly and effectively to a diverse array of pathogens, providing the body with the ability to recognize and respond to countless potential threats.

Thus, the requirement of three segments of DNA is vital for the generation of the functional