lecture 2 - genetics of antigen recognition receptors

Question 1

multiple genes encode for a single

Answer 1

lymphocyte giving more variation

Question 2

heavy chain and TCRbeta is encoded by three genes

Answer 2

V, D and J

Question 3

light chains and TCRalpha is encoded by two genes

Answer 3

V and J

Question 4

what is rearrangement

Answer 4

these genes break and rejoin in a different way to form a functional gene

Question 5

what process carries out rearrangement

Answer 5

Non-homologous end joining (NHEJ)

Question 6

light chain example:
DNA is broken between what regions

Answer 6

V and J regions

Question 7

then a single J is brought next to a

Answer 7

single V

Question 8

this joining is unique to

Answer 8

each specific cell

Question 9

this rejoined DNA is then transcribed producing which region of the light chain

Answer 9

the V region

Question 10

what are the two loci containing L chain genes

Answer 10

lamda locus and kappa locus

Question 11

heavy chain example:
first the DNA is broken between which genes

Answer 11

a D and J gene

Question 12

a D and J are then brought together. DNA is then broken between

Answer 12

the V and the DJ

Question 13

then the DJ is joined to a

Answer 13

random V gene

Question 14

then this heavy chain pairs up with what

Answer 14

a random light chain

Question 15

the light chain is assembled first in which loci

Answer 15

kappa locus

Question 16

sometimes joining the light chain made form the kappa locus to the heavy chain is unsuccessful.
it then tries in the

Answer 16

lamda locus

Question 17

in heavy chains when the random VDJ genes are brought together it is then joined to a

Answer 17

constant region

Question 18

the constant region joined determines the

Answer 18

isotype of the antibody

Question 19

what genes are important in this rearrangement of the genes

Answer 19

RAG-1 and RAG-2 (recombination activating gene)

Question 20

mutations in RAG genes results in

Answer 20

immunodeficiency

Question 21

recombination signal sequences are on the end of the V, D and J genes. RAG binds to these sequences and

Answer 21

joins the genes together

Question 22

what enzyme adds random bases at the junctions further adding diversity

Answer 22

TdT enzyme

Question 23

allelic exclusion:
each chromosome has two of the same genes
allelic exclusion ensures that an individual B cell only produces

Answer 23

one specific antibody as RAG genes are turned off

Question 24

what is imprecise joining

Answer 24

small differences in position of join, adds junctional diversity

Question 25

further diversity due to somatic hypermutation

Answer 25

mutation frequency in heavy chain variant genes are higher than normal mutation rate

Question 26

what enzyme causes somatic hypermutation

Answer 26

activation induced deaminase (AID)

Question 27

what does AID do

Answer 27

deaminates cytosil to uracil

Question 28

uracil is recognised by error prone DNA repair pathways leading to mutations

Question 29

class-switching gives more diversity

Answer 29

the VDJ joins to an IgM first as its the closest to VDJ
later on the VDJ joins to a different constant region