L03

Question 1

T cells leave the bone marrow before B cells. where is T cell gene rearrangement take place

Answer 1

thymus

Question 2

what process is not involved in generating the diversity of TCR

Answer 2

SMH

Question 3

what chromosome encodes for TCR alpha

Answer 3

14

Question 4

what chromosome encodes for TCR beta

Answer 4

7

Question 5

what chromosome encodes for TCR gamma

Answer 5

7

Question 6

what chromosome encodes for TCR delta

Answer 6

14

Question 7

gene rearrangement happens to MHC molecules

Answer 7

False

Question 8

where is MHC molecule (HLA) in humans located

Answer 8

chromosome 6

Question 9

what cells express MHC class 2

Answer 9

B cells, macrophages, dendritic cells (antigen presenting cells, APC)

Question 10

T cells express both MHC classes

Answer 10

true

Question 11

how many different MHC molecules can a person have

Answer 11

12 if they are heterozygous for all 6 MHC loci

Question 12

what are the 3 MHC class 1 molecules

Answer 12

HLA-A, HLA-B and HLA-C

Question 13

what are the 3 MHC class 2 molecules

Answer 13

HLA-DP, HLA-DQ and HLA-DR

Question 14

Location of polymorphic residues within MHC structure is random

Answer 14

false

Question 15

where is the most variable region of the MHC molecule

Answer 15

peptide binding domain

Question 16

what might MHC polymorphism lead to

Answer 16

increases risk of immune-mediated disease e.g. autoimmune diseases (i.e. increases likelihood of presenting self Ags.)

reduces pool of available donor organs for transplantation
(as MHC alleles on donor organ should match those of the
recipient for best outcome)

Question 17

what peptides are presented on MHC class 1

Answer 17

peptides derived from protein Ags synthesized inside a cell (endogenous Ag e.g. from an intracellular pathogen such as a virus)

Question 18

what peptides are presented by MHC 2

Answer 18

peptides derived from protein Ags taken up from the outside of the cell (exogenous Ag e.g. from an extracellular pathogen such as a bacterium/fungus)

Question 19

peptides are processed before presenting in endogenous and exogenous Ag

Answer 19

True

Question 20

what are the steps of presenting peptides on MHC 1

Answer 20

1) Ag. (e.g. viral protein) synthesized in cytoplasm

2) protein cleaved to peptides by proteasome

3) peptides transported to endoplasmic reticulum by TAP transporter

4) peptides bind to MHC class I molecules

5) MHC-I/peptide complex then transported to cell surface

Question 21

what is the proteosome function

Answer 21

cytoplasmic protein turnover

Question 22

proteasomes in cells receiving inflammatory cytokines signals are modified to produce altered peptides

Answer 22

True

Question 23

what is TAP

Answer 23

TAP is a component of a multi-protein assembly, the peptide loading complex
also includes tapasin and calreticulin

Question 24

what does TAP do

Answer 24

delivers a peptide that binds to the MHC 1 and completes its folding

the fully folded MHC 1 is released from the TAP complex and exported

Question 25

TAP is a dimer with a hole in the middle

Answer 25

True

Question 26

what are the steps of presenting peptides on MHC 2

Answer 26

1) Ag. (e.g. bacteria) endocytosed into intracellular vesicles inside the cell

2) protein cleaved to peptides by acid proteases in vesicles

3) vesicles fuse with vesicles containing MHC class II molecules

4) peptides bind MHC class II molecules

5) MHC-II/peptide complex then transported inside vesicles to cell surface

Question 27

what does MHC class II molecules binding to invariant chain in the ER

Answer 27

this prevents peptides binding in the groove

Question 28

what are the steps of unblocking MHC 2

Answer 28

invariant chain forms a complex with MHC 2 blocking binding of peptides and misfolding the protein

it is cleaved in an acidified endosome, leaving a short peptide fragment, CLIP, still bound to MHC 2

endocytosed Ag are degraded to peptides in endosome but CLIP is still blocking the binding of the peptides with MHC 2

HLA-DM binds to the MHC 2, releasing CLIP and allowing other peptides to bind and MHC 2 then travels to the surface.

Question 29

what happens to MHC molecules in healthy cells

Answer 29

MHC molecules present self proteins

Question 30

Accessory molecules involved in antigen processing and presentation are also encoded within the MHC (TAP and LMP (class I pathway ) HLA-DM (class II pathway ))

Answer 30

True

Question 31

which cells recognize and kill cells infected by viruses

Answer 31

cytotoxic CD8 T cells

Question 32

What do cells that express MHC 2 (APC) do

Answer 32

take up and present extracellular Ag to activate helper CD4+ T cells

Question 33

some other cell types can express MHC class II under certain conditions allowing them to be recognized by helper CD4+ T cells.

Answer 33

True