Question

What are the two rearrangement events that occur at the heavy chain locus?

a) V-D-J and V-J
b) V-D and D-J
c) V-J and D-J
d) V-D-J and D

Answer 1

The two rearrangement events at the heavy chain locus are V-D-J and D-J, which produce the unique variable region of an antibody's heavy chain.

Step-by-step explanation:

The two rearrangement events that occur at the heavy chain locus are V-D-J and D-J. During B cell development, DNA recombinase randomly selects and excises various V (Variable), D (Diversity), and J (Joining) segments from the heavy chain locus. These segments are then rearranged to create a unique variable region for each antibody. The first rearrangement joins a D segment to a J segment, and then a V segment is joined to the DJ complex, forming the V-D-J rearrangement that ultimately codes for the variable region of the heavy chain of an antibody.