Reading...
Play button
Play button
Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
26 Cards in this Set
- Front
- Back
|
What did Tonegawa conclude about 'Jumping Genes'?
|
As the B cell matures, rearrangements in DNA of heavy and light chains occur --> different gene segments brought together to code for entire V region, intervening sequences removed
|
|
|
How does the immune system make a wide range of proteins from single segments of DNA?
What about this process is completely unique to the immune system? |
By making different arrangements of V-, J-, and D-regions
Rearrangement leads to PERMANENT loss of intervening chromosomal material |
|
|
What do RAG-1 and RAG-2 do?
|
Recombinases that help rearrange DNA to bring V, D, and J segments together
|
|
|
What encodes the V regions of the heavy chain?
|
3 gene segments:
V (variable) D (diversity) J (joining) |
|
|
What is the order of recombination in encoding for the V region of the heavy chain?
|
D first recombines with J, then V combines with DJ
|
|
|
On what chromosome is the Human H chain locus?
|
Chromosome 14
|
|
|
What regions are responsible for encoding the light chain?
|
V and J
|
|
|
What are two types of L chains?
|
V kappa, V lambda
|
|
|
On which chromosome is the kappa chain locus?
|
Chromosome 2
|
|
|
On which chromosome is the lambda chain locus?
|
Chromosome 22
|
|
|
In what order are the H chains and L chains made via gene rearrangement?
On what type of cells does this process only occur? |
H chain first
L chains next: kappa, then lambda Only occurs on B cells, angtigen-independent |
|
|
What are the steps for production of a heavy chain?
Where do these events occur? |
Nucleus:
Germline DNA --> somatic recombination --> DJ together --> somatic recombination --> VDJ --> transcription --> RNA Cytoplasm: RNA splicing --> mRNA --> translation --> polypeptide chain |
|
|
What are the steps for production of a light chain?
|
Nucleus
Germline DNA --> somatic recombination --> VJ joined --> transcription --> RNA Cytoplasm: RNA --> splicing --> mRNA --> translation --> polypeptide chain |
|
|
What are heptamer/nonamer recognition sequences?
How are they removed? |
23 or 12 base pair separations between V, D, and J regions
Removed when RAG recombination proteins bind, create double stranded DNA breaks--> gaps filled in by DNA polymerase |
|
|
What is allelic exclusion?
What does this create? |
Each cell selects only ONE parental Vheavy and one parental Vlight (kappa or lambda)
Each B cell clone has one BCR |
|
|
What is the process of allelic exclusion of heavy chains?
|
Rearrangement starts on both alleles
When one rearrangement is successful, other allele is silenced --> stimulates kappa gene rearrangement If neither allele successful, cell death |
|
|
What is the process of allelic exclusion in light chains?
|
Kappa chain rearrangement first; if successful, silences other allele, starts lambda allele
|
|
|
What is combinational diversity?
|
Different V, D, and Js
|
|
|
What is junctional diversity?
|
Random removal/insertion of nucleotides between V, D, and J
|
|
|
What is somatic hypermutation?
|
When IgM and IgD are expressed on B cells, Tcell-Bcell interaction activates neurotransmitter sequence changes in the VDJ area
|
|
|
What is clonality?
|
Net outcome of allelic exclusion = single B cell Ig has 2 identical H chains, 2 identical L chains, and one specificity determined by the shape/size of the VH/VL binding groove
|
|
|
What are 6 factors that contribute to the generation of diversity?
|
1. Multiple V, D, and J segments to choose from
2. Combinatorial diversity - V, D, and J order 3. Junctional diversity - imprecise joining of V, D, and J 4. N-region diversity - insertion/deletion of extra nucleotides (exonucleotides remove nucleotides, TdT adds) 5. Random assortment of heavy chain with 2 light chains 6. Receptor editing |
|
|
What are the two types of TCR?
What kinds of gene segments make them up? |
alpha-beta
delta-gamma alpha and gamma determined by VJ beta and delta determined by VDJ |
|
|
What are the chromosomal locations of the following human TCR genes?
a. TCR beta b. TCR alpha and delta c. TCR gamma |
a. chrom. 7
b. chrom 14 c. chrom 7 |
|
|
What are 5 factors that promote TCR diversity?
|
a. Multiple V, D, and J segments
b. Junctional diversity c. combinatorial diversity d. N-region diversity e. alpha chain is not allelicaly excluded (some T cells have 2 receptors) |
|
|
What are 2 differences between ab and dg TCRs?
|
1. gd-TCRs have fewer V, D, J segments --> less diversity; also less junctional diversity
2. ab-TCRs can be biclonal (2 alphas) or monoclonal gd-TCRs are allelically excluded, always monoclonal |
