Lecture 23 Flashcards
Adaptive immunity has:
memory
The affinity of B cells towards antigens:
Increases with time and persistence of antigen
Which adaptive immunity response is stronger and more rapid?
Secondary compared to primary
Adaptive immunity relies on:
Gene arrangement or recombination
What is a transposase?
The enzyme that operates on the transposase
The ancient transposases in your genome are called
Recognition Activation Sequences (RAG1 or RAG2)
Recognition sequences (RS) are
Base pair sequences found at the ends of any gene segments that rearranges - RS are the substrate for RAG1 and RAG1 directed combination.
Antibodies are formed from:
repeated Ig domains.
Two antiparallel b-pleated sheets are joined in the middle by:
a disulphide bond.
The antibody molecule consists of
4 protein chains and repeating Id domains.
How many L domains and how many H domains
2 domains in L and 4-5 in H
Antibody protein structure:
L–s-s–H–s-s–H–s-s–L. The two H chains are disuplhide linked.
The antigen binding sties are located at the ::
tip of the two arms. Formed from the N terminal domains of the L and H chains.
The effector region:
invariant, bound by Fc receptors and complement component C1.
IgM
The default Ig made by all naive B cells.
The membrane(monomer) form of IgM is:
the B-cell antigen receptor (BCR)
The soluble (pentamer) has how many antigen binding sites
10
Affinity:
When the sum of attractive molecular forces at two surfaces exceeds the repulsive forces, there is affinity
Avidity:
Avidity results from multiple affinity contacts. Like velcro.
IgG:
Gene name Y, activates complement, placental transfer, 20mg/ml
IgM
Gene name U, activates complement, membrane bound form
IgA
Gene name A, secreted at mucosal surfaces
IgD
Membrane bound form
IgE:
High affinity receptor on mast cells
Amino acid variation is found in:
3 regiosn called the complementartity determining regions (CDR). These are the 3 loops that connect the strands in the 1st domains of the H and L chains.
How many identical antigen binding sites?
2
Light chain locus has no ___ segments
D
RAG1 and RAG2 (Recombination activation gene) are responsible for:
Rearrangement and are only active in B and T lymphocytes
In H gene locus:
D to J then V to D. Intervening DNA is lost.
In Lk gene locus
V to J
Imprecise joining results in:
Massive amino acid diversity in the CDR3 loop on the antigen receptor
Receptor cominbations are made ___
as randomly as possible
Each B cell is generated before birth with a ___
unique B cell receptor
B cells encounter antigen in ___
lymph nodes/
Somatic hypermutation of the Ig gene results in:
Some clones with higher antigen receptor affinity.
After successive rounds of somatic hypermutation of the Ig gene:
The mature B cell becomes a plasma cell secreting soluble Ig.
Some B cells reside in lymph nodes as ___
long-term memory cells.
Clostridium tetani is:
A common soil bacterium that proudces tetanus toxin (TT)
TT is:
a neurotoxin that binds to the presynaptic membrane of the neuromuscular junction and causes lockjaw
Vacciniating with Tetanus Toxin does what:
Drives affinity maturation of those IgM antibodies into high affinity IgG antibodies that block TT receptor binding.
The Ig and TcR gene loci are segmented into:
variable, diversity and joining regions.
Each naive B cell represents:
a unique antigen specificity
Antigen drives:
Clonal selection and expansion in lymph node follicles.
What is the reason why immunization works?
Affinity maturation
