chapter 6 - antigen receptor genes Flashcards
There is no limit to the number of antigens that can be recognized, so how do receptors recognize them all?
we don’t have a receptor for every combination so..
genes get rearraged at the DNA lelvle and we can recognize these rearrangments
the immune systems has multiple genes and “re-use” the same genes
How does the inherotance of most genes owrk
maternal and paternal DNA that combines through fertilization and produces patrnal form of protein and maternla form of protein
what’s special about the gene inheritance of B cells?
they are clonal so one B cell produces only 1 antibody
explain the paradigm shift found from the experiment of Hozumi and Tonegawa in 1976
they took embryonic liver cells and antibody-producing tumor cells and cut the DNA with restriction endonuclease
then elctrophores was done to separte by size so that the larger pieces were near the top and the lighter peices were near the bottom
these where blotted onto nitrocellulose paper detected by radiogel
they found that the DNA from antibodies had lighter segemnts meaning that DNA came toegther and lost the longer peices since only small ones where plated
what are antibodies made of?
proteins made by B cells that bind an antigen
4 polypetides connected via disulfide bonds
explain the structure of antibodies
4 polypetides connected via disulfide bonds
there is the light chian and the heavy chain
where is the vraible region and tge constant region
where is the N terminus and the C terminus
top (two arms) - varaible region and N terminus
the bottom (one branch) - constant region and the C terminus
where does effector activity take place?
the constant region
what latin letters can the the light chain be and the heavy chain be
light - kappa and gamma
heavy - mew, kappa, aplpha, beta, and weird e
where do antigens bind to the antibody?
the varaible region
when an antibody is exposed to papain digestion what occurs/
the variable region disconnect from the constant region
what happens when the antibody is exposed to mercaptoethanol reduction?
all the strand disconnect so we have two ehavy chains and two light chains
what happnes when the antibody is exposed to pepsin digestion?
the lose the effector region and keep the antigen binding region
what is the Fc part and Fab parts of the antibody?
Fc- consatnt region
Fab- varaible regions/ the arms
how is the secrrted and membrane Ig the same or different then the normal antibody?
the secreted and membrane Ig have the same N terminus however they have different C terminuses
where do antibodies interect with ag?
at the complementarity determining regions (CDR)
these CDR regions are the loops in the Fab regions
the rest ifs the framework regions
what binds the antigen and what allows signaling into the cell?
binds - Fab (CDR)
Signaling into cell - Ig alpha and Ig beta
what kind of bonds exist between the antibody and antigen?
non-covalent bonds
Anti-toxin/ anti-serum/ immunity, discuss it
for certain disease such as tetanus and diptheria we do not develop immunity after having naturally acquired it
so we can inject a small amount of the toxin into animals such as horses, these animals then produce antigens and the serum can be taken from the animlas and injected into huamns
what is mithridatism?
protection agasnit poison can be observed in reponse to small doses of poisons being ingested over time
talk about how the isolation and discovery of antibodies was done
so the serum is isolated from rabbits that have been injected with Ovalbumin
electrophoresis is used to separate the proteins by size and charge
when the antibody is preincubated with the antigen there is less globulins gamma present
overall we have albumin (positive side), alpha globulun, beta globulin, and gamma globulin(negative side)
the antibodies (Ab) = immunoglobulin (Ig)
how do agglutination reactions work?
the presecne of a lattice means we have antibody and antigen
the presencce of a button means only antigen
the zone of equivalence is where these signs will show
using aglutination we can see how the valncy of antibodies and antigens are improatnt. Describe some examples
univalent antigen + antibody = no cross linking
multivalent antigen + antibody = cross linking
multivalent antigen + only Fab region of antibody = no cross linking
multivalent antigen + (Fab)2 antibody = cross linking
how is the DNA ligand identifiable
when antibody and antigen interact it forms a triangle
what are the biological consequences to Ag binding
1) virus neutralization - prevents pathogen binding
2) opsonization - lead to pahgocytosis
3) complement fixation and formation of the membrane attack complexes - (holes in membrane) leads to phagocytosis or lysis
4) antibody -dependent cell mediated cytotoxicity (ADCC) - Ig binds to infected cells or tumors and then NK comes and kill them so NK induced apoptosis
5) transcytosis - moving the Ab accross the epthiptheal layer (placenta)
what is virus neutralization
Ab binding blocks binding of toxin or virus to cell
what is oponsisation
promotes phagocytosis of Ag via interaction with Ab
what is activation of complemtns?
directky destroys cells
what is ADCC?
killing by NK cells
what is transcytosis?
moving the Ab accross the epthiptheal layer (placenta)
whihc of the 5 consquences of Ag binding is not mediated by the Fc region of antibody?
neutralization of viruses
