Iho : Ig Gene Org And Expression

Front 1

For immunoglobulin genes, the joining of a number of the exons occurs via a rearrangement of the gene segments at what level?

Back 1

DNA rather than at the level of mRNA

Front 2

What does Ig expression start with?

Back 2

IgM and IgD to the final Ig AGE

Front 3

What do the C gene segments (constant regions) give rise to?

Back 3

GAMED isotypes

Front 4

What are the gene segments that heavy chain genes are assembled from?

Back 4

VDJ and C

Front 5

What are the two types of light chains?

Back 5

kappa and lambda

Front 6

Each of the Ig light chain genes is assembled by the rearrangement of what?

Back 6

VJ and C gene segments

Front 7

How does rearrangement occur?

Back 7

Between specific sites on the DNA called Recombination signal sequences or RSS

Front 8

What is rearrangement catalyzed by?

Back 8

RAG-1 and RAG-2

Front 9

inverted repeats that allow the DNA to form a stem-loop with them aligning on the stem.

Back 9

RSS

Front 10

RSS 7 and 9 signal sequences are separated by what?

Back 10

1 turn of DNA (12 bp spacer) or 2 turns of DNA (23 bp spacer)

Front 11

Ensures that gene segments are joined in the correct order

Back 11

12/23 rule of RSS

Front 12

Joint made in forming the small circle of DNA that has no function in the rearrangement process

Back 12

Signal joint

Front 13

occurs if the number of nucleotides added across the joining region allows the genetic code to be read in phase.

Back 13

Productive rearrangement

Front 14

occurs if the number of nucleotides added across the joining region causes the genetic code to be read out of phase (the majority of times).

Back 14

Nonproductive rearrangement

Front 15

What does a nonproductive rearrangement result in?

Back 15

an incomplete antibody (run into stop codons) B cell may be able to productively rearrange the Ig gene on the other chromosome, otherwise death of the B cell.

Front 16

occurs when only one of two alleles is expressed.

Back 16

Alleleic Exclusion

Front 17

ensures that a given B cell will make antibody molecules with only a single specificity.

Back 17

Alleleic Exclusion

Front 18

Mature (but not activated) B cells initially express what on their external cell membranes?

Back 18

IgD and IgM

Front 19

As mature B cells are activated to divide and differentiate by their cognate antigen, they switch from membrane-bound IgD and IgM to what?

Back 19

secretory IgM

Front 20

Where does the choice of expressing IgD or IgM on a B cell occur and why does this matter?

Back 20

Occurs at the level of processing mRNA so a given B cell can both express IgD and IgM

Front 21

Where does the switch from membrane bound IgD and IgM to secretory IgM occur?

Back 21

the level of processing of mRNA transcripts

Front 22

What levels of switching occur at the level of DNA?

Back 22

IGM --> G->E-->A

Front 23

If the second polyadenylation site is read, then the mRNA for membrane-bound what is generated by splicing?

Back 23

IgM

Front 24

If the fourth polyadenylation site is read, then the mRNA for membrane-bound what is generated by alternate splicing?

Back 24

IgD

Front 25

Of the secreted IgM what establishes the creation of S-S bonds between IgM antibodies?

Back 25

Cysteine

Front 26

When is the mRNA for secreted IgM produced?

Back 26

When the M1, M2 exons are spliced out

Front 27

What is required for class switching to cocur?

Back 27

Activation of the B cell

Front 28

What leads to the production of IgG mRNAs?

Back 28

Looping event that cuts out the constant regions for IgM and IgD at the level of DNA

Front 29

Proliferation cytokines

Back 29

IL 2,4,5

Front 30

What class switching does IFN-gamma stimulate?

Back 30

IgG2a

Front 31

What class switching does IL-4 stimulate?

Back 31

IgG1, IgE

Front 32

What class switching does IL-5 stimulate?

Back 32

IgE

Front 33

What happens if mutations lead to less Ab affinity?

Back 33

The B cell dies

Front 34

Mutations that accumulate in the Ig gene as the B cell proliferates

Back 34

Somatic Hypermutation

Front 35

Where are mutations of Ig concentrated?

Back 35

in the variable region

Front 36

When a mutation leads to an antibody that binds the antigen more firmly

Back 36

Affinity maturation

Front 37

What chromosome do you see in CML?

Back 37

Philadelphia (novel chromo 22) Translocation of 9 to 22

Front 38

Translocation of chromo 9 and 22

Back 38

CML

Front 39

Reciprocal translocation of choromo 8 and 14

Back 39

Burkitt's lymphoma

Front 40

Concept of making an antibody that mimics an antigen

Back 40

Anti-Idiotopic antibody