part 7

Question 1

what does HLA stand for

Answer 1

human leukocyte antigen

Question 2

which chromosome is MHC genes located on

Answer 2

6

Question 3

how many genes encode for the alpha region of MHC I

Answer 3

3

Question 4

which genes encode for alpha region MHC I

Answer 4

HLA A, B, and C

Question 5

what genes encode for alpha and beta chains of MHC II

Answer 5

HLA-DR, -DP, and -DQ encodes for MHC II alpha and beta chains.
DRa, DRb, DPa, DPb, DQa, DQb.
There is a subgroup of humans that have -DRb2.
Depending on the person, there can be 3-4 MHC II pairs

Question 6

what properties do MHCs have genetically

Answer 6

polygenic and polymorphic

Question 7

what is polygenic

Answer 7

many genes

Question 8

what is polymorphic

Answer 8

many alleles/forms

Question 9

what operon is similar to MHC operon

Answer 9

lac

Question 10

what turns on the MHC operon

Answer 10

cytokines

Question 11

what does IFN turn on

Answer 11

transcription factors like CIITA

Question 12

what does CIITA do

Answer 12

CIITA protein coordinates various proteins to turn on MHC class II gene transcription and allow the production of MHC class II proteins`

Question 13

since there are many combinations/alleles of MHC, why is this important

Answer 13

for tissue/MHC matching

Question 14

what kind of dominance do MHC genes have

Answer 14

codominance

Question 15

what does codominance allow for in MHC

Answer 15

creates diversity

Question 16

what is always expressed

Answer 16

Genes are always expressed, alleles are what is specifically expressed.

Question 17

is polygeny or polymorphy more important

Answer 17

polygeny

Question 18

what is the first step of polymorphism development

Answer 18

Ancestral MHC gene undergoes gene duplication and divergence

Question 19

second step of polymorphism development

Answer 19

multiple MHC genes are created

Question 20

third step of polymorphism development

Answer 20

gene conversion between misaligned chromosomes during meiosis

Question 21

what is gene conversion

Answer 21

gene A fragment does not swap with A, but with B

Question 22

fourth step of polymorphism development

Answer 22

chromosomes separate during meiosis

Question 23

what is alloreactivity

Answer 23

MHC portions are recognized in foreign tissue

Question 24

what happens if the wrong MHC is transplanted

Answer 24

alloreactivity
1-10% of T cells being activated (very harmful)
shock and rejection

Question 25

what percentage of cells are activated during an immune response

Answer 25

.001%

Question 26

what are superantigens

Answer 26

Some bacteria and viruses
cause unnecessary activation of T cells by allowing for MHC/antigen binding
MHC is bound by T cells no matter the shape

Question 27

what percentage of T cells are activated for superantigen

Answer 27

20%

Question 28

how do superantigens avoid immune system

Answer 28

preoccupy the immune system, which allow the pathogen to proliferate and avoid response

Question 29

why isn’t there more MHC restriction

Answer 29

If there was more MHC restriction, they would have to go through positive and negative selection, which would kill too many MHCs

Question 30

what does the T cell need from B cell in order for antigen to be recognized

Answer 30

correct MHC shape and correct epitope shape