Generation of Antibody Diversity

Question 1

what is V(D)J recombination?

Answer 1

process of DNA recombination that contributes to the immense diversity of antibody and T cell receptors

Question 2

why are recombination-activating genes 1 and 2 (RAG1 and RAG2) important?

Answer 2

components of V(D)J recombination in developing B and T cells: cannot make B or T cells without

Question 3

true/false: the generation of diversity of antigen-specific receptors on both B and T cells has many common features

Answer 3

true

Question 4

what genes are rearranged in V(D)J recombination?

Answer 4

Ig for B cells
TCR for T cells

Question 5

what are the two major domains in an antibody light chain?

Answer 5

variable region and constant region

Question 6

what codes for the variable region in the light chain?

Answer 6

variable (V) segment
joining (J) segment

Question 7

what enzyme mediates the rearrangement of receptor genes?

Answer 7

V(D)J recombinase

Question 8

what gene segments code for the heavy chain?

Answer 8

variable (V) segment
diversity (D) segment
joining (J) segment

Question 9

does the heavy chain have one or multiple genes coding for the constant region?

Answer 9

multiple

Question 10

what constant region genes in the heavy chain can be expressed in the primary transcript?

Answer 10

mu and delta
mu leads to IgM polypeptides
delta leads to IgD polypeptides

Question 11

what is germ line diversity?

Answer 11

an individual has multiple different V, D, and J gene segments, and multiple alleles for each exist in the population

Question 12

what is combinatorial diversity?

Answer 12

V, D, J combinations in heavy chain rearrangement
different combinations of heavy and light chains

Question 13

what is junctional diversity?

Answer 13

randomly added and subtracted nucleotides from joining segments

Question 14

when does somatic hypermutation occur?

Answer 14

after antigenic stimulation of the B cells

Question 15

in what species is gene conversion the major mechanism of antibody diversification?

Answer 15

chicken, rabbit, cattle, and sheep

Question 16

do the IgM and IgD on a mature B cell have identical antigen specificities?

Answer 16

yes- their variable regions are exactly the same and are both produced on the primary B cell

Question 17

true/false: in chickens, somatic hypermutation is the principal mechanism to create antibody diversity in B cells developing in the bursa of Fabricius

Answer 17

false

Question 18

what is class switch recombination?

Answer 18

after a B cell is exposed to an antigen, it can switch to produce different classes of antibody molecules: IgG, IgE, IgA, still retain same antigen specificity

Question 19

what is class switching dependent on?

Answer 19

antigenic stimulation
cytokines released by T cells

Question 20

true/false: a naive B cell expresses both IgM and IgD as a result of class switch recombination

Answer 20

false: alternative splicing of RNA leads to both IgM and IgD on the naive B cell
class switching is DNA

Question 21

is class switching for heavy chains, light chains, or both?

Answer 21

heavy chains

Question 22

after class switching, how many classes can a B cell express?

Answer 22

one antibody class

Question 23

true/false: a memory B cell can express IgG, IgA, or IgE on its surface

Answer 23

true

Question 24

true/false: the VL domain of Ig light chain forms as a result of VDJ recombination

Answer 24

false: only VJ

Question 25

true/false: gene conversion in B cells occurs in lymph nodes

Answer 25

false: only in chickens, sheep, rabbit, cattle, in primary lymphoid organs

Question 26

what does the leader sequence in the variable light chain gene segment code for (also heavy chain)?

Answer 26

signal peptide that targets the translated polypeptide to the membrane of the cell