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25 Cards in this Set
- Front
- Back
Name the gene segments that are involved in the formation of heavy and light chain variable regions.
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Heavy chain variable region - mew, epsilon, delta, gamma, alpha
Light chain variable regions - lambda and kappa |
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Explain how the formation of Ig proteins from multiple gene segments contributes to the antibody repertoire
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Each Ig protein is produced from a unique combination of gene segments so that it can make the antibody repertoire have literally infinite specificities
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Describe the RSS feature of gene segments that ensures that the correct sequences are joined. ie what prevents a V segment from rearranging with another V segment
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the rss segment is when you have a heptamer and a nonamer seperated either by 12 sequences or 23 sequences. A 12 sequence can only recombine with a 23 sequence.
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Define junctional diversity and understand what causes it.
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When the segments are spliced together tDt adds new non genomic nucleotides to the splice junctions. that provides uniqueness and adds to the diversity of the Ig molecule
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What are the four antigen independent mechanisms that contribute to the development of the antibody repertoire?
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1) V and J combinations
2) V J and D combinations 3) junctional diversity 4) heavy chain and light chain combinations |
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What is the purpose of the southern analysis of IgDNA from Liver DNA and B cell DNA?
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we want to see if we can see proof of DNA rearrangement
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How does the southern analysis of Liver and B cell DNA work? How do you do that experiment?
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1) you do a restriction enzyme digest of DNA from non lymphoid or B cell DNA population
2) seperate the DNA by gel electroporeisis and hybridize to membrane 3) probe for DNA complementary to heavy chain C region or heavy Chain V region C <sub>H</sub> or V<sub>H<sub> |
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What are the results of the experiment with Southern hybridization and what do they tell you?
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You get the same size fragment for the C region and V region in the B cell whereas you get different size fragments in the non lymphoid cell.
This tells you that DNA rearragement has occured because you get the same size fragment for both which means they are in the same area (?) |
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what are the four organizational features of human Ig loci?
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1)one loci for heavy chains
2) one loci for kappa chains 3) one loci for lambda chains 4) multiple genes on each loci |
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Where are the V regions of the Ig molecules located?
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at the 5' regions
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How are the v regions arranged?? (2 things)
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-300 bp
-families |
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Which gene loci have multiple Cs and which gene loci have single Cs?
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kappa has a single c
heavy chain and lambda have multiple cs |
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Where are the V, D and J, C segments located?
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All loci have the V, C and J segments
Only the heavy chain loci have the D segments |
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What is the difference between the heavy chain variable region and the light chain variable region?
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-The heavy chain variable region loci has the V D and J genes
-The light chain variable region loci has the V and J genes |
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What does V, D and J stand for?
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V = variable region
D = diversity region J = joining region |
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What is the 12-23 rule?
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an RSS consisting of a conserved heptamer and nonamer seperated by 12 bases can only recombine with a RSS consisting of a conserved heptamer and nonamer seperated by 23 bases
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What are the three stages of gene segement recombination?
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1)RAG binds the RSS at the heptamer on the two ends (heptamer of a V and heptamer of a J)
2) RAG cleaves the heptamer producing a hairpin loop 3) ends are joined |
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What is formed when the ends of the recombinant gene is ligated?
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1) signal joint of DNA that was eliminated
2) coding joint which is the V and J region connected |
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What are the three steps of actually joining the recombination sequence?
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1) cleavage generates a palindromic sequence
2) cleaved ends can be modified before pairing 3) coding joint is formed with novel non genomic DNA |
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What are the 8 steps of cleavage and recombination sequence in specifics?
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1) RAG binds to and cleaves double stranded DNA at RSS
2)creates a double stranded palindromic hair pin 3) hairpin is cleaved to yeild single stranded palindromic sequence (P sequence) 4) TdT adds nucleotides 5) single strands are paired 6) unpaired nucleotides are removed by exonuclease 7) gaps are filled by DNA synthesis and ligation 8)coding joint is formed with novel non genomic DNA |
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What are the four antigen independent ways that we develop diversity?
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1) multiple v genes
2) V D J recombinations and V J recominbations 3) H and L combinations 4) junctional diversity |
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How do you get VDJ next to C mew?
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differential RNA processing
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What combinations do you get to make IgM
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VDJ plus C mew
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What recominations do you get to make IgD
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VDJ plus V delta
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Are IgM and IgD expression antigen independent?
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yes
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