Lymphocyte Receptor Diversity

Question 1

What is the B cell receptor made of?

Answer 1

4 polypeptide chains

Question 2

What are the parts of the 4 polypeptide chains in B cell receptor?

Answer 2

-2 shorter chains -> light chains
- 2 longer chains -> heavy chains

Question 3

Where do antigens bind on B cell receptors?

Answer 3

areas where there are both heavy and light chains

Question 4

How many antigen binding sites on B cell receptors?

Answer 4

2

Question 5

What are the antigen binding sites referred to as?

Answer 5

Fab portion of receptor

Question 6

What does the Fe portion of the B cell receptor contain?

Answer 6

only heavy chains

Question 7

What does the Fe portion of the B cell receptor bind to?

Answer 7

• B cell membrane
• Fe receptors on other immune cells when secreted as an antibody

Question 8

What does the Fe portion of B cell receptor determines?

Answer 8

effector function

Question 9

What do light chains and heavy chains have on B cell receptors?

Answer 9

variable and constant regions

Question 10

What does variation in antigen occur due to?

Answer 10

variable regions

Question 11

What are constant regions of light chains on B cell receptor?

Answer 11

λ or κ

Question 12

What are constant regions of heavy chains on B cell receptor?

Answer 12

one of 5 classes

Question 13

What are the 5 classes of heavy chains on B cell receptor?

Answer 13

α, δ, ε, γ, m

Question 14

What antibody is α heavy chain for?

Answer 14

IgA antibody (a dimer)

Question 15

What antibody is δ heavy chain for?

Answer 15

IgD antibody

Question 16

What antibody is ε heavy chain for?

Answer 16

IgE antibody

Question 17

What antibody is γ heavy chain for?

Answer 17

IgG antibody

Question 18

What antibody is m heavy chain for?

Answer 18

IgM antibody (a pentamer)

Question 19

How is B cell receptor diversity generated?

Answer 19

• gene recombination
• gene conversion

Question 20

Where does gene recombination for BCR occur?

Answer 20

variable regions of light and heavy chain

Question 21

What genes does the variable region of light chains contain BCR?

Answer 21

V and J

Question 22

How does gene recombination for light chains occur BCR?

Answer 22

1 V gene and 1 J gene are randomly selected and put together with constant region gene

Question 23

What genes does the variable region of heavy chains contain BCR?

Answer 23

V, D, and J

Question 24

How does gene recombination occur for variable regions of heavy chains BCR?

Answer 24

1 V gene, 1 D gene, and 1 J gene are randomly selected and put together with constant region gene

Question 25

Outcome gene recombination BCR?

Answer 25

light chain and heavy chain are put together to form a B cell receptor specific for a unique antigen

Question 26

Where does gene conversion happen BCR?

Answer 26

only in V gene

Question 27

How does gene conversion happen BCR?

Answer 27

- uracil randomly inserted into V gene - seen as an error and uracil is cut out, leave a space - pseudogene sequences that are upstream of the V gene are inserted to fill space - now have completely different V gene

Question 28

What are the types of T cell receptors?

Answer 28

- α β TCRs - γ δ TCRs

Question 29

What are the majority of TCRs?

Answer 29

α β TCRs

Question 30

What is each TCR made of?

Answer 30

2 polypeptide chains

Question 31

What does each polypeptide chain of a TCR contain?

Answer 31

a variable region and a constant region

Question 32

How is diversity of TCRs achieved?

Answer 32

gene recombination

Question 33

What genes does α chain of TCR contain?

Answer 33

V, J, and 1 constant

Question 34

How does gene recombination of α chain of TCR occur?

Answer 34

random selection of 1 V gene and 1 J gene, and then these genes get put with the C gene

Question 35

What genes does β chain of TCR contain?

Answer 35

V, D, J, and 2 constant genes

Question 36

How does gene recombination of β chain of TCR occur?

Answer 36

random selection of 1 V gene, 1 J gene, 1 D gene, and 1 constant gene, and then put together

Question 37

What is unique about gene recombination of β chain TCR?

Answer 37

D gene is option or multiple D genes can be selected

Question 38

Where does junctional diversity occur TCR?

Answer 38

occurs at junctions between the different genes on α and β chains

Question 39

What ways does junctional diversity occur TCR?

Answer 39

- base insertion - base deletion

Question 40

What is base insertion TCR?

Answer 40

random nucleotides are inserted at junctions between V, (D), and J genes

Question 41

How many nucleotides may be added between V and D genes in base insertion TCR?

Answer 41

5 nucleotides

Question 42

How many nucleotides may be added between D and J genes in base insertion TCR?

Answer 42

4 nucleotides

Question 43

What is base deletion TCR?

Answer 43

random nucleotides made be removed between genes

Question 44

What does MHC stand for?

Answer 44

major histocompatibility complex

Question 45

Where is MHC -I found?

Answer 45

in all nucleated cells

Question 46

Where is MHC- II

Answer 46

professional APCs

Question 47

What are the professional APCs?

Answer 47

- macrophages - dendritic cells - B cells

Question 48

What does MHC-I present?

Answer 48

endogenous antigen

Question 49

What is an endogenous antigen?

Answer 49

antigen comes from intracellular locations, within the cell

Question 50

What can endogenous antigens be?

Answer 50

normal (self) or due to an infection (nonself)

Question 51

What do MHC-II present?

Answer 51

exogenous antigen

Question 52

What is an exogenous antigen?

Answer 52

antigen comes from extracellular locations (outside the cell)

Question 53

How do MHC-I present antigen?

Answer 53

antigen broken into smaller pieces and these pieces can be presented on MHC-I

Question 54

How do MHC-II present antigen?

Answer 54

antigen is phagocytized or internalized, broken into smaller pieces, and these pieces can then be presented on MHC-II