Generation of Diversity in immune system

Question 1

What is the total number of antibodies that can be produced?

Answer 1

about 10¹¹

Question 2

How is huge genetic diveristy in antigen production produced?

Answer 2

Somatic recombination

Question 3

How many gene segments encode the heavy chain V region?

Answer 3

3

Question 4

How many gene segments encode the light chain V region?

Answer 4

2

Question 5

What are the 3 gene segments which encode the heavy chain V region?

Answer 5

V, D, J

Question 6

What are the 2 gene segments which encode the light chain v region?

Answer 6

V, J

Question 7

What is the diversity of antibodies determined by?

Answer 7

• different V, D, J regions
• different V and J regions

Question 8

What are the 2 types of light chain called?

Answer 8

• Kappa
• Lambda

Question 9

What order are the gene segments in the heavy chain in?

Answer 9

VDJC

Question 10

What are the 4 ways antibody diversity is generated?

Answer 10

• Combinatorial diversity
• Junctional diversity
• N-nucleotide addition/deletion
• Different heavy chains with different light chains

Question 11

What is junctional diversity?

Answer 11

Imprecise segment joining between gene segments

Question 12

What is combinatorial diversity?

Answer 12

The combination of different V, D, and J chains

Question 13

What is N nucleotide addition?

Answer 13

Nucleotides may be lost or added when the joins in DNA are made

Question 14

How is the problem of autoreactivity produced?

Answer 14

Random generation of antibodies produces some antibodies which recognise self

Question 15

How is the problem of autoreactivity partially solved?

Answer 15

When engagement of antigen receptors of autoreactive cells occurs, apoptosis is induced

Question 16

What is negative selection?

Answer 16

When strongly autoreactive B and T cells are apoptosed

Question 17

What is a problem with negative selection?

Answer 17

Weakly autoreactive B cells are released into the periphery rather than being apoptosed like strongly autoreactive cells

Question 18

What happens to B cell receptors if they are non-functional?

Answer 18

First the rearrangement of the second allele occurs and if this still is not successful then apoptosis occurs

Question 19

What is affinity maturation?

Answer 19

In a B cell immune response over days antigen binding becomes much stronger due to somatic hypermutation in the variable region genes . The antibodies mutate to give a better fit.

Question 20

Where does affinity maturation occur?

Answer 20

In the germinal centres

Question 21

What does affinity maturation require?

Answer 21

T cell help

Question 22

Describe the structure of T cell receptors

Answer 22

Made up of 2 chains, alpha and beta

Question 23

What is estimated number of T cell receptors which can be produced?

Answer 23

10¹⁸

Question 24

How many different gene segments make up to beta portion of T cell receptors?

Answer 24

3

V,J,D

Question 25

How many different gene segments make up the alpha portion of T cell receptors?

Answer 25

2

V and J

Question 26

How can the diversity of T cell receptors be produced?

Answer 26

Somatic recombination

Question 27

Do T cell receptors undergo somatic hypermutation?

Answer 27

No

Question 28

What is the order of rearrangement of the chains of T cell receptors?

Question 29

What kind of TCRs does positive and negative selection select for?

Answer 29

TCRs that bind weakly to self MHC alleles

Question 31

What kind of TCRs are selected against in positive selection?

Answer 31

TCRs that don’t bind to self MHC

Question 32

What kind of TCRs are selected against in negative selection?

Answer 32

• TCRs that bond strongly to self MHC alleles
• TCRs that bind strongly to self MHC plus self peptide