Receptor generation and lymphocyte development Flashcards
(14 cards)
What does CDR stand for
complementary determining regions
Describe the segments of gene sequence of the heavy chain in CDR
- D V J and C segments
- from H locus
Describe the gene sequence of light chain CRR
- V J and C segments
- from lambda and kappa loci
What is meant by junctional diversity
- additional nucleotides inserted at random
- between V D and J segments
- further increases variability
- through somatic recombination
How do recombination signal sequences regulate the number of V J or D segments there are? [2]
- sequences with the same spacers can’t join together
- therefore two of the same segments can’t join together
What is the role of TdT in V(D)J recombination
where there ice TdT random nucleotide will be added
What is the role of Artemis:DNA-PK complex in V(D)J recombination
cleaves DNA hairpin at random site
to yield single strand of DNA
Define the term hairpin
nucleotide sequence that is not double stranded
What is the role of RAG enzymes
bring together different V(D)J segments, random
Identify some reasons as to why a B/T cell won’t survive development [3]
- fails to express pre-antigen
- fails to express antigen receptor
- too string antigen recognition
Why are T/B cells killed if they bind too strongly to to antigen during development [3]
- likely recognising mHC rather than peptide
- may cause T/B cell to react to self if let loose
- thus prevent autoimmune disease
Where does B cell negative selection occur?
bone marrow
Where does T cell development occur?
thymus
How is the the development of CD4 helper T cells and CD8 cytotoxic T cells rdetermiend? [2]
- If TCRMHC II then CD8 cells are down regulated, cell becomes CD4
- If TCR are activated by MC I CD4 cells will be down regulated, cell becomes CD8
