chapter 6

Question 1

B cells use groups of PARTS of genes to create
different possible antibodies using _____________________

Answer 1

recombination

Question 2

What are the different gene segments that undergo recombination?

Answer 2

variable (v)
diversity (d)
joining (j)
constant (c)

Question 3

Which segments are used in antibody heavy chains only?

Answer 3

D segments

Question 4

What gene segments are included on Kappa light-chain?

Answer 4

V, J, and C

Question 5

How many Vk gene families and Jk segments do mice have?

Answer 5

18 and 4

Question 6

Lambda light-chain genes pair each ________segment with a
particular ________ segment

Answer 6

J
C

Question 7

Only 5% of mouse Igs have lambda light chains due to ________________

Answer 7

a loss of most of the Vλ segments

Question 8

In humans, what percent of light chains are lambda type?

Answer 8

40%

Question 9

What segments are included on the heavy chain?

Answer 9

V, D, J, and C

Question 10

-flank each antibody gene segment
-has a conserved nonamer and heptamer sequence

Answer 10

recombination signal sequences (RSS)

Question 11

In between the nonamer/heptamer lies either a _____________ sequence

Answer 11

12 or a 23 bp spacer

Question 12

what is the “12/23 rule?”

Answer 12

the spacing and arrangement dictates that a 12 bp RSS must pair with a 23 bp RSS for recombination to occur.

Question 13

In between the nonamer/heptamer sequence lies ____________________________

Answer 13

either a 12 or a 23 bp spacer sequence

Question 14

What enzyme joins the gene segments?

Answer 14

RAG1/2 recombinase

Question 15

What does RAG stand for?

Answer 15

recombination activating gene

Question 16

Which RAG is more important?

Answer 16

RAG1; it forms a complex with RSSs stabilized by
binding RAG2

Question 17

V(D)J recombination results in a functional Ig ________________

Answer 17

variable region gene

Question 18

How can V(D)J recombination occur between segments
transcribed in either the same or opposite directions?

Answer 18

So long as the correct RSSs are lined up, orientation of the actual gene segment is irrelevant

Question 19

What are the 5 mechanisms that generate antibody diversity in naive B cells?

Answer 19

1. multiple gene segments
2. P nucleotide addition
3. exonuclease trimming
4. non-templated N nucleotide addition
5. combinatorial diversity

Question 20

multiple gene segments determines what?

Answer 20

which gene segments are put together

Question 21

templated nucleotide addition between joints, resulting from asymmetrical cleaving of hairpin structures

Answer 21

P nucleotide addition

Question 22

sometimes occurs at junctions, losing nucleotides and changing reading frames

Answer 22

exonuclease trimming

Question 23

mediated by TdT activity, adding in random nucleotides between joints

Answer 23

Non-templated N nucleotide addition

Question 24

combinatorial diversity determines what?

Answer 24

which heavy chains pair with which light chains

Question 25

ensures that each B cell synthesizes only one heavy and one light chain

Answer 25

allelic exclusion

Question 26

Describe the ordered heavy/light chain recombination process:

Answer 26

-heavy chains and recombined and expressed first
-expression of a functional heavy chain shuts down recombination machinery temporarily
-the heavy chain is paired with a surrogate light chain to form a pre-BCR
-if that works, then the machinery is started back up and light chain takes place

Question 27

Nonreproductive arrangements can lead to what during development?

Answer 27

apoptosis

Question 28

receptor editing of potentially ______________receptors occurs in light chains.

Answer 28

autoreactive

Question 29

which two antibodies are expressed by mature B cells?

Answer 29

IgM and IgD

Question 30

how is mRNA splicing involved in expression of IgM and IgD antibodies?

Answer 30

it removes the intervening spacer between VDJ and C, leaving VDJC mRNA ready to be translated

Question 31

Primary transcripts for IgM heavy chains may result from _______________ transcribing through both the IgM and IgD constant regions

Answer 31

RNA polymerase

Question 32

The _________________ are similar in structure to the antibody light chain

Answer 32

α and γ chain

Question 33

The _______________ are similar in structure to the antibody heavy chain

Answer 33

β and δ chain