Question

Which of the following do you expect would be actively functioning in a B cell that had migrated to a germinal center?

1) RAG-1
2) Artemis
3) AID
4) Ku70
5) None of the above

Answer 1

In a B cell within a germinal center, Activation-induced cytidine deaminase (AID) would be actively functioning, facilitating somatic hypermutation and class switch recombination.

Step-by-step explanation:

The question relates to the functioning of a B cell that has migrated to a germinal center. Among the choices provided, Activation-induced cytidine deaminase (AID) is the enzyme expected to be actively functioning in a B cell within the germinal center. AID is critical for the processes of somatic hypermutation and class switch recombination, which are essential for the diversification of antibody responses during an immune reaction.

RAG-1 is involved in the initial rearrangement of B and T cell receptors but is not active in mature B cells in germinal centers. Artemis is associated with opening hairpin DNA structures during V(D)J recombination, which occurs earlier in B cell development. Ku70 is part of the non-homologous end joining (NHEJ) pathway important for repairing double-strand breaks but is generally not involved in the somatic hypermutation or class-switch recombination processes in germinal centers.