Major Histocompatiblity Complex Flashcards Preview

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Flashcards in Major Histocompatiblity Complex Deck (19)
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1
Q

MHC

A

First recognized as the site of genes that cause T cells to reject tissues transplanted from unrelated donors to recipients
- MHC in humans is called Human leukocyte antigen complex

2
Q

Isotypes

A

Products of the different MHC 1 and 2 genes

3
Q

Alleles

A

Different forms of any given gene

4
Q

Allotypes

A

Different products of any given gene

5
Q

MHC diversity

A

Much smaller than that of TCR

  • multiple gene families
  • genetic polymorphism
6
Q

How many MHC class 1 isotypes do you have?

A

6 classes, get each one from your parent = 12 isotypes

7
Q

MHC class 1 locus

A

A-G

8
Q

Heterozygous

A

Individual that inherited 2 different forms (alleles) of the gene from parents
- better to be heterozygous than homozygous

9
Q

Homozygous

A

Individual that inherited the same forms (alleles) of the gene from parents

10
Q

HLA haplotype

A

Particular combination of HLA alleles found on a given chromosome 6

11
Q

HLA type

A

Combination of all HLA alleles a person has

12
Q

T cells can not recognize an _____ in the absence of _____

A

Antigen; MHC

13
Q

Difference between survivors and fatalities when an infectious disease strikes a population

A

The complement of MHC molecules present in each individual
- species wide MHC polymorphisms dramatically reduce likelihood that a single infectious agent will destroy an entire population

14
Q

Species most prone to genetic bottlenecking

A
  • African cheetahs
  • Florida panthers
  • Lions in Tanzani
15
Q

Advantage of multiple MHC genes that arise from balancing selection

A
  • contribute different peptide binding specificities
  • greater number of pathogen derived peptides is presented during any infection
  • strength of immune response against the pathogen is improved by increasing number of activated pathogen specific T cells
  • high degree of MHC polymorphism ensures that most members of population are heterozygotes
16
Q

Directional selection

A

Favors certain MHC alleles at the expense of others and is imposed by specific, epidemic disease

  • replaces older alleles with newer variants
  • outcome is change, not balance
17
Q

MHC in domestic animals

A
  • all mammals have MHC 1,2, and 3
  • express differences in their conserved and variable regions
  • MHC class 2 and 3 are orthologous
  • MHC class 1 genes are paralogous
  • overall molecular structure and function of MHC molecules does not differ significantly
18
Q

MHC class 3

A
  • 4 genes for complement receptors, P450, TNF alpha, lymphotoxins, NK receptors, HSP
19
Q

Why do we have 2 different classes of MHC?

A

Helps to discriminate between different pathogens, do not need to send all pathogens thru the same pathway