chapter 6 b - recombination

Question 1

Abs come in isotypes (aka flavprs) that have different strictures and specialities what are these isotypes?

Answer 1

they have 5 different CH segments and 5 different heavy chain segment

IgM - mew
IgD - delta
IgG - gamma
IgE - epsilon
IgA - alpha

Question 2

how is the selction of B cell done? how does clonal selction occur?

Answer 2

based on how the Ag interacts with the BCR proliferation and differentiation occur

Question 3

in the light chain what can be said about the V and C regions

Answer 3

the V regions in DNA are different

the C regions are cosntant (same)

Question 4

what are myelomas? what do they secret?

Answer 4

plasma cancer cells
they secret the same IgL (light chain)

Question 5

what is just the IgL called?

Answer 5

Bence Jones proteins

2 types of light chain x 2 parents = 4 possible C gene alleles

Question 6

light and heavy chains are encoded for by multiple gene segments that form 1 gene; these gene segments are shuffled to form the Ag binding region or the ____

Answer 6

V domain

Question 7

how does rearrangement in the light chain work?

Answer 7

we lose gentic material between the V and J zones

Question 8

how does reaaragnmnet in the heavy chain work?

Answer 8

lose gentic material between D and J segments and then between the DJ and V segemnts

Question 9

where does early B cell development occur? independent of what?

Answer 9

in the BM is where the light and heavy chains reaarnage and it is indepednent of the antigen

Question 10

what is joining regulated by?

Answer 10

the RSS segments on the DNA

Question 11

what is the rule the RSS segemsnt follow?

Answer 11

the 12/23 rule meaning a 12 RSS can only join with a 23 RSS

Question 12

whats the difference between productive and non-productive reaarangment?

Answer 12

productive - makes a protein

non-productive - no proatein can be created

Question 13

what enzymes are responisble for joining and cutiing of DNA

Answer 13

RAG1 and RAG2
Recombination-activating Gene

other prteins repair the cut ends

Question 14

how many gene segemnst exist in the light chain vs the heavy chain?

Answer 14

2 and 3

Question 15

when is the heavy cahin expressed and when is the light chain expressed?

Answer 15

heavy - pre-B cell
light naive B-cell

Question 16

how does RAG1/2 work?

Answer 16

it recognized the RSS regions to join and cut

Question 17

how does the process of DNA rearrangement work

Answer 17

1. cleave at the 5prime end
2. sequences at the signal junction results from the joining of the two heptameric regions
3. usualy a 3 prime over hang
   4.cleavage of the hairpin generates sites for P nucleotide addition
4. in heavy chains we losee some P nucleotides and N nucleotides are added

P and N nucleotides increase diveristy

Question 18

what happens if the V and J recombinant regions lie in the same direction? ( so they face each other)

Answer 18

when splicing the DNA and recombining it we form a loop of DAN instead of a line, this loop is then lost after fruther cell divisons

we still have one starnd produced with correct orientnetaion

the signal join is lost

Question 19

what happens if the V and J recombinant regions lie in the opposite direction? ( so they face away from each other)

Answer 19

when we splice the DNA we are able to invert a part so it fits and that the signal joint can reamin in the genomic DNA

Question 20

how does the cell deal with extra DAN that does not contribute to the Ig?

Answer 20

the signal joint remain in the DNA upstream of the recombinent antibidy gene

it ignores it through RNA processing
DNA
Precursor-mRNA
Processed-mRNA

Question 21

how can a B cekk express membrane and secrtion forms of the same Ab?

Answer 21

due to RNA processing

Question 22

what are the mechanism of diversity during B cell development?

Answer 22

-combinatorial diveristy
V x D x J or V x J

• junctional diveristy
  flexible joining at RSS sequence
  P and N nucleotide addition
• combinatorial pairing of the heavy and the light chains