Final answer:
In a normal human thymocyte, there are 26 possible Dβ-Jβ combinations for each TCR β chain due to the presence of two different Dβ segments and 13 different Jβ segments. Since there are two rearrangement events, the total number is doubled, resulting in 52 possible rearrangements.
Step-by-step explanation:
The question you asked is related to the possible number of Dβ-Jβ rearrangements in a normal human thymocyte. The process of V(D)J recombination is a mechanism of genetic recombination that occurs in the immune system's developing B and T cells. It helps create a diverse repertoire of T-cell receptors (TCRs) and immunoglobulins (antibodies).
For the β chain of the TCR, there are two different Dβ segments and 13 different Jβ segments. During T cell development, one Dβ segment is combined with one Jβ segment through rearrangement. This means there are 2 x 13, or 26 possible Dβ-Jβ combinations for each TCR β chain. However, since there are two rearrangement events for the β chain during thymocyte development, this consequently doubles the number of rearrangements to 52.