Final: What Happens When You Get Sick? Flashcards Preview

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Flashcards in Final: What Happens When You Get Sick? Deck (21)

polyclonal response

b cell that binds an antigen is recruited by t cells and sent to the lymph nodes



part of the antigen that binds


where do somatic hypermutation and affinity maturation take place?

lymph nodes


why do b cell clones that already bind the antigen go to the lymph nodes?

to improve binding affinity


what are the sites of somatic hypermutation and affinity maturation

germinal centers in the lymph nodes


what do hypermutation and affinity maturation do

mutates antibody gene where the hypervariable parts of the protein are coded

all 3 hypervariable regions of both hvy and light chains are mutated

if new antibody has a higher affinity they multiply and mutate again

if lower affinity they die


where does class-switching recombination take place

lymph nodes


class switching recombination

somatic hypermutation stops after antibody has high affinity

the cell then works on the constant part of hvy chain

DNA splicing takes place

puts 1/5 "Ig" tool onto the constant region


5 types of Ig tools

IgM, IgD, IgA, IgE, IgG


IgE on mast cells cause

inflammation in response to allergens


what is a major histocompatibility complex (MHC)?

3rd kind of surface cell receptor attached to membranes of most cells in the body, not just immune cells

bind and display short polypeptides ~10 aas (chopped up proteins) on cell surface

hold pp in a groove


two kinds of MHC

MHC I displays fragments of proteins from inside the cell (endogenous proteins)

MHC II displays fragments of proteins taken from outside the cell (exogenous proteins)



almost all cells in the body display MHC I

important in weeding out infected or cancerous cells

constantly checked by killer t cells (CD8)

if foreign fragment, killer t kills (kiss of death)

simplist way to rid body of infection (viral)



important in directing b cells to secrete antibodies

MHC II checked by helper t cells (CD4), which bind the antigen the antibody is holding (handshake)

this stimulates b cell to turn into plasma cells and go to the lymph nodes

leads to somatic hypermutation and affinity maturation


peptide displayed in MHC must interact with...

either TCR of a helper or killer t cell


what is an HLA gene

human leukocyte antigen

genes that make MHC proteins

short arm of chromosome 6


HLA genes

MHC I genes are in one place and MHC II in a different place

each chromosome 6 has multiple versions of MHC receptors

these are multiple genes that code for different versions of MHC I & II

MHC I and MHC II genes are always expressed togehter


the HLA genes have a huge number of _____


3 main MHC I genes have hundreds of alleles

3 main MHC II genes have about 100 alleles


HLA haplotype

set of HLA alleles on one chromosome

a person has 2 HLA haplotypes and all alleles are expressed at the same time


HLA diversity increases the number of ways the immune system can ___ proteins


diversity is an advantage in MHC I & II receptors


problem with organ transplants

MHC diversity

organs from other people are never a perfect match (unless identical twin)

HLA haplotypes of donor and recipient must be matched