CH. 7: Organization and Expression of Lymphocyte Antigen Receptor Genes

Question 1

Describe the rearrangement of the light chain.

Answer 1

• DNA is cut
• V and J gene segments are joined together by V(D)J recombinase
• VJ gene segment join together with C gene

Question 2

Describe the rearrangement of the heavy chain.

Answer 2

• DNA is cut
• D and J gene segments are joined together
• DJ gene segment is joined with V gene segment, then C gene segment

Question 3

Explain class switching.

Answer 3

• allows B cells to change the type of antibody they produce
• all have the same variable domains as original antibody generated in immature B cell during process of V(D)J recombination, but possessing different constant domains in heavy chains
• C-region segments of DNA are switched with other C-region segments

Question 4

What is somatic hypermutation?

Answer 4

• random point mutation in recombined V(D)J unit of antibody H or L chain V region genes
• increases the antibodies’ binding to antigen (affinity)