2. Recognition of antigen by T and B cell receptors

Question 1

What do all immunoglobulin chains have?

Answer 1

Characteristic folded structure of 7-10 Beta strands linked via a disulphide bond

Question 2

What are regions of hypervariability also called?

Answer 2

Complement determining regions (CDRs)

Question 3

Similarities between TCR and BCR

Answer 3

TCR resembles a membrane bound Fab fragment

Hypervariable regions are similar to IgH HVRs but TCR has also got HVR4

Question 4

Which length peptides do MHC I bind?

Answer 4

8-10 AA

Question 5

Which length peptides do MHC II bind?

Answer 5

13-17 AA

Question 6

Which regions of the TCR interact with the peptide itself in MHC and TCR interaction?

Answer 6

HVR3 alpha and HVR 3 beta

Question 7

What are the light chain and heavy chain segments in BCRs?

Answer 7

light - V and J

heavy - V D J

Question 8

Chromosome where the lambda light chain locus is

Answer 8

Chromosome 22

Question 9

Chromosome where the kappa light chain locus is

Answer 9

Chromosome 2

Question 10

Chromosome where the heavy chain locus is

Answer 10

Chromosome 14

Question 11

What are RAG1 and - 2 responsible for in somatic recombination?

Answer 11

Binding the 12 and 23 RSS sequences, drawing them together and cleaving them

Question 12

Which 2 enzymes repair the nicks created by RAG 1/2

Answer 12

Ku 70

Ku 80

Question 13

Which 2 enzymes open up the hairpin?

Answer 13

Artemis

DNA protein kinase

Question 14

What does Tdt do?

Answer 14

Adds in nucleotides RANDOMLY

non templated nucleotide addition

Question 15

Which enzymes ligate the DNA after recombination?

Answer 15

DNA ligase IV

XRCC4 ligase

Question 16

Why is the action of Tdt so important?

Answer 16

Adds junctional variation

Question 17

4 Ways in which diversity is generated in the immunoglobulin repertoire

Answer 17

1. Combinatorial diversity during segment recombination
2. Junctional diversity during segment joining
3. Combinatorial diversity driven by different combinations of light and heavy chains
4. JUST BCR - Somatic hypermutation

Question 18

How much diversity to TCR and BCRs have?

Answer 18

TCR - 10^18

BCR - 5 x 10^13

Question 19

Why do TCRs have more diversity?

Answer 19

Have to recognise specific MHC as well as epitope