Antibody Diversity

Question 1

RAG-1/2

Answer 1

Recombination activation genes

Mutation in these leads to host who is susceptible to a large variety of pathogens due to low number of B and T cells

Question 2

somatic recombination

Answer 2

generates huge B cell repertoire, permanently alters the gremline DNA

Question 3

kappa chain

Answer 3

chromosome 2

Question 4

lambda chain

Answer 4

chromosome 22

Question 5

heavy chain

Answer 5

chromosome 14

Question 6

Heavy chain somatic recombination

Answer 6

D recombines with V
VD recombines with J to produce VDJ which encodes the variable region
VDJ recombines with C
occurs first before light chain recombination

Question 7

Light chain recombination

Answer 7

V recombines with J
VJ is the variable region
VJ then recombines with C
kappa occurs first then lambda

Question 8

terminal deoxynucleotidyl transferase (Tdt)

Answer 8

catalyzes the addition of random nucleotides between the gene segments that are joined
(heavy chains of B cells and beta chains of T cells only)

Question 9

somatic hypermutation

Answer 9

when B cell proliferates it accumulates mutations affected the variable region, those mutations that confer better specificity for antigens are selected for resulting in affinity maturation

Question 10

T/F class switching only changes the constant regions of the heavy chains?

Answer 10

true

Question 11

T/F class switching affects the function of the antibody but not the specificity?

Answer 11

true

Question 12

Why is class switching to IgD not possible?

Answer 12

No switch region precedes it

Question 13

activation-induced cytosine deaminase (AID)

Answer 13

catalyzes recombination events leading to class switching 
also required for somatic hypermutation

Question 14

Class switching is driven by ____

Answer 14

T helper cells

Question 15

Hyper IgM syndrome

Answer 15

due to a genetic deficiency of AID, can’t class switch

Question 16

IL-7

Answer 16

produced by bone marrow stream cells, important in growth/development of B cells
Lack of this does not affect B cell number but B cells are nonfunctional

Question 17

Bruton’s Tyrosine Kinase

Answer 17

important for proper signal transduction from cell-surface receptors during B cell development
genetic deficiency of this leads to low number of B cells

Question 18

mature B cell has on its surface

Answer 18

IgM and IgD

Question 19

allelic exclusion

Answer 19

ensures that only one chromosome is active in encoding heavy and light chains

Question 20

consequence if allelic exclusion were employed

Answer 20

multiple different B cell receptors with different affinity would be on one B cell