1.4 antibody diversity Flashcards
(44 cards)
how does B cell produce antibodies?
- B cell encounteres and binds antigen
- stimulated B cell gives rise to plasma cell
- plasma cell makes antibodies
what is an antibody made up of?
- N terminus and C terminus (n binds antigen)
- light chain
- heavy chain
- hinge region
what does hinge region allow?
antibody to bind to unique epitope on each side ( antibody can bend and reognize epitopes not in the same place)
IgG can be cleaved by ______ and that leaves 2Fab and 1 FC (tail)
papain
Fab can be used in ______
diagnostic testing
there are ___ types of heavy chains and ____ types of light chain that make up 5 immunoglobulin classes
5,2
if you grab an antibody thats coiled up and straighten it out, you would see the _____
hypervariable regions
the hyper-variable regions are where?
at the tip/the antigen binding site
the variability of the binding site allows the antibody to ________
recognize a certain type of foreign molecule
bonding between Ab chains and an antigen are _____
non-covalent
multivalent antigens can have ______ or ______
different epitopes or a repeated epitope
epitopes can be_______ or _____
linear (Amino acids right after another)
discontinuous (amino acids from different sections, if you denature the antigen you denature the stimuation)
what causes the antibody diversity in the genomic structure?
the variable diversity joining
somatic recombination happens during the _____
maturation process of B cells
a random V + random J + random D = random VDJ joint and the information inbetween them is ____-
cut out
12/23 rule
prevents rearrangement of V or J genes within their own clusters and ensures the obligatory inclusion of a D segment in heavy chain genes
How does recombination happen?
- 2 RAG molecules bind (one recognizes 12, one recognizes 23)
- two RAGs come together and detach/float away
- the V/J are joined together
light chain vs heavy chain somatic recombination?
light chain: V+J join and inner info is cut out
heavy chain: D+J join, info is excised, then DJ join V
Junctional diversity
how sides join after RAGs cut off and float away
steps of junctional diversity?
- heptamers are clipped
- hair pin forms bw 2x2 nucleotides and swings it out to be a 4x1
- TdT adds nucleotides randomly until it finds a homology, trims the end, and then the joints are filled in
what is TdT
terminal di-oxy transferase
adds nucleotides to ends of palindromic strands
B cell early life steps
- each B cell undergoes somatic recombination
- unique VDJ = unique junctional diversity
- this encodes a unique binding site
4, we may/may not be able to transcribe this whole thing due to combination of nucleotides - we must be able to transcribe/translate this whole thing
there is strong ______ in B lymphocytes
allelic exclusion ( allows each mature B lymphocyte to only express one type of immunoglobulin)
there are always _____ next to B cell receptors, they just arent drawn all the time
IgB, Iga
