DNA Recombination/Hypermutation Flashcards
T-cell receptor does not bind to antigen directly, but to _________
Peptides bound to MHC molecules
Production of antibodies (2 steps):
1) Clonal selection and expansion (Naive B or T cells) 2) Differentiation (Activated B cells undergo changes including differentiation into antibody-secreting plasma cells and memory B cells)
Combinatorial diversity
Random combo of V,D,J or V and J segments, random joining of IgH and IgL chains/alpha/gamma/beta chains
Junctional diversity
Introduction of “palindromic” and “new” nucleotides between gene segment segments
Why are genes for only one antigen receptor expressed per B and T cell?
Allelic exclusion
Immunoglobulin class switch initiated in connection with ___________
Immune responses
How does Ig class switch benefit immune response?
Diff immunoglobulin classes have diff functions, tailors response to diff pathogens
Ig class switch ONLY takes place in _______
Ig heavy-chain
Affinity maturation of B cell antigen receptors occurs in encounter with _________
Antigen
B cells with _______________ selected in immune responses
Higher affinity receptors
Due to alternate RNA processing:
1) Simultaneous expression of IgD and IgM on naive B cells or 2) Production of secreted antibody versus membrane bound Ig
Affinity maturation associated with:
Somatic hypermutation
This leads to affinity maturation
AID-mediated point mutations on IgH and IgL variable regions
MHC
Major histocompatibility complex
In Ig variable region, mutations accumulate in ________
Complementarity-determining regions (CDRs)
