2. First a review… Adopt as a perspective that:
One B-cell produces one antibody
Make that perspective more exacting:
One B-cell produces one idiotype.
Cassettes (V, J, [D],) (aka gene segments) “fuse” (to make an idiotype).
Fusing occurs because RAG recognizes one turn/two turn signals on cassettes.
CDR3 develops through junctional flexibility (trimming) and addition of P & N nucleotides (expanding).
CDR1 and CDR2 (especially) and CDR3 become more varied because of somatic hypermutation.

3. First a review… now with images
And, I will use images from a different source.
Remember to be critical of what “interpretative” drawings convey…

4. First a review… now with images

5. First a review… still with images
RAG: what does it do? …how does it work?

6. First a review… still with more images
RAG: what does it do? …how does it work?
…what about P&N nucleotides?

7. PART IV (some new stuff)
How do immunoglobulins assemble?
Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference?
Similarly, identical variable regions can be shared among different isotypes. How?
B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?

8. How do immunoglobulins assemble?

9. Some immunoglobulins are in the surface membrane of immature B-cells while other immunoglobulins of the same idiotype are secreted by mature B-cells. What’s the difference?

10. Similarly, identical variable regions can be shared among different isotypes. How?

11. B-cells are diploids with two sets of genetic instructions
B-cells are diploids with two sets of genetic instructions. How does just one set get expressed?

12. The general scheme of B-cell development
STEM CELL 
pro (genitor) Bcell
pre Bcell
Ag-selected ( stimulated)- Bcell
Ab secreting plasma cell