Immunology T2

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Describe BCR heavy & light chain
Both chains have a constant and variable domain. Folded structure (7-10 B strand linked via disulfide bond). Regions of hypervariability (important for diversity)
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The regions of hypervariability are also called.....
CDRs
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Are there any similarities between TCR + BCR?
TCR resembles a membrane bound FAB fragment BUT is encoded by a different set of gene segments
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What kind of receptor is a TCR? Draw structure
Heterodimeric membrane bound receptor
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How are peptides bound to MHC I and II molecules?
1) MHC I are held tightly at each end (anchored, 8-10AAs) 2) MHC II extend beyond the groove, hold longer chains (13-17AAs). Interacts with peptide backbone via H bonds + ionic interactions
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Peptides which bind to MHC I have....
structurally related anchor residues and are variable in length. Certain AAs in certain positions
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What is the role of CD4+ and CD8+ surface proteins?
They stabilise the binding of TCR to MHC:Peptide complex. CD4 = single molecule CD8 = hetero/**** dimer
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Where are the binding sites for CD4 & CD8 on MHC II and I?
Immunoglobulin domains
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Where are MHC I and II expressed?
MHC I expressed on all cell types. MHC II expressed on APCs
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How are variale region genes constructed?
Constructed from somatic recombination of seperate gene segments. C = constant J = joining region, Germline DNA. D segment in heavy chain. DJ joins first, V joins DJ segment. Transcription + Translation
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Name the two light chains
kappa (κ), lambda (λ),
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What are RSS sequences?
Recombination signal sequence. Rearrangement of V, D, J segments is guided by RSS sequences. 2 Types (23 RSS & 12 RSS) 12-23 Rule - A 23 flanking segment will only join with a 12
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How are V region gene segments joined?
By recombination 12-23 Rule. Forward + Reverse orientation. Coding and signal joints.
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What cleaves RSSs and opens up the hairpin? What does TdT do?
RAG 1,2 cleave RSSs. DNA PK and Artemis open up hairpin. TdT adds nucleotides - junctional variation. Ligation by DNA ligase.
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Name the 4 main processes that generate diversity of immunoglobulin repertorie?
1) Combinational diversity during segment recombination 2) Junctional diversity during segment joining (TdT) 3) Combinational diversity driven by diff combinations of H + L chains. 4) Somatic hypermutation (increases specificity)
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Compare the diversity of TCR & BCR
H chain has a larger amount of diversity than L chain. TCR have higher diversity than BCR because of hypervariable region of MHC. T cells have to recognise different type of MHC molecule as well as peptide
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Other cards in this set

Card 2

Front

The regions of hypervariability are also called.....

Back

CDRs

Card 3

Front

Are there any similarities between TCR + BCR?

Back

Preview of the front of card 3

Card 4

Front

What kind of receptor is a TCR? Draw structure

Back

Preview of the front of card 4

Card 5

Front

How are peptides bound to MHC I and II molecules?

Back

Preview of the front of card 5
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