Final answer:
The gene segments that come together to make a functional gene for the variable region in B-cells are V, D, and J segments for the heavy chain, and V and J segments for the light chain.
Step-by-step explanation:
The gene segments that need to come together to make a functional gene for the variable region in B-cells for heavy and light chains are as follows:
- For the heavy chain: V (Variable), D (Diversity), and J (Joining) segments.
- For the light chain: V (Variable) and J (Joining) segments.
These gene segments undergo genetic rearrangement, resulting in millions of unique antigen-binding sites for the B-cell receptor (BCR).