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Immunology Final > Quiz 4 Part 1 > Flashcards

Quiz 4 Part 1 Flashcards

1
Q

name similarities that T cells have to B cells

A

express highly variable ANTIGEN SPECIFIC receptors

receptors are produced by gene rearrangements (like somatic recombination)

express only a single type of receptor on each cell

the receptor on the T cell resembles the fab fragments

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2
Q

which are more diverse — T cells or B cells?

A

T cells.

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3
Q

Do T cells and B cells differ in the antigens that they recognize?

A

yes!
T cells recognize small peptides while B cells recognize structural components

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4
Q

Is there a secreted form of a T cell?

A

no — only receptor

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5
Q

does somatic hypermutation and isotype switching happen in T cells?

A

no

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6
Q

thoroughly explain the structure of a T cell receptor

A

very similar to a fab fragment

there is a variable region, constant region, and a transmembrane region. There is a cytoplasmic tail that branches off from the transmembrane region and sticks into the cytoplasm

there is an alpha chain and a beta chain.
hypervariable loops that serve as the antigen binding site

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7
Q

the alpha chain of a T cell receptor is similar to the ____ chain of an antibody

the beta chain of a T cell receptor is similar to the ____ chain of an antibody (B cell receptor)

A

alpha chain = light chain. undergoes a SINGLE somatic recombination event (VJ recombination)

beta chain = heavy chain. Undergoes TWO somatic recombination events. (dj, then vdj

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8
Q

What enzyme carries out recombination in T cells?

A

same as B cell — RAG complex and DNA recombinases

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9
Q

Does junctional diversity also exist in T cells?

A

yes! (P and N nucleotides)

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10
Q

What is the name of the disease in which the person has NO RAG PROTEINS

A

SCID (severe combined immunodeficiency disease)

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11
Q

What is the name of the syndrome in which the person has PARTIAL RAG activity

A

Omenn syndrome

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12
Q

is somatic recombination happening on DNA or RNA

A

DNA

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13
Q

T cells undergo virtually the same somatic recombination as B cells. However, what is the difference

A

T cells have more distinct gene segments

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14
Q

Which have more diversity —– T cells or immunoglobulins?

A

T cells

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15
Q

Which has more variability for the “J” (joining) segments —– alpha chain or beta chain?

A

alpha chain has more variability for the joining segments

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16
Q

Can T cell receptors be expressed on the cell surface without help?

A

NO – it needs help

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17
Q

what “helpers” aid the T cell receptor in being expressed on the surface

A

the T cell receptor associates with 4 invariant membrane proteins

3 in CD3 complex, called CD3Y (gamma), CD3delta, and CD3 epsilon

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18
Q

the TCR complex is assembled from how many polypeptides?
break it down

A

8 polypeptides
alpha and beta chains (2)
2 CD3episolon (2)
1 CD3delta (1)
1 CD3gamma (1)
2 zeta chains (2)

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19
Q

what are the functions of:

a.) the alpha and beta chains

b.) CD3epsilon, CD3delta, CD3gamma, and the zeta chain

A

the alpha and beta chains bring about antigen recognition

the others bring about signal transduction

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20
Q

TCR’s can either have alpha and beta chains or __ and ___ chains

A

gamma and delta

21
Q

which are made more:

alpha and beta chains

or

gamma and delta chains

A

alpha and beta

22
Q

alpha matches with _____ and beta matches with ____

A

alpha —> gamma

beta —> delta

23
Q

Can a t cell express alpha and delta?

A

NO

it’s either alpha and beta OR gamma and delta

cant be both

24
Q

which is more diverse (has more gene segments)

alpha and beta or gamma and delta

A

alpha and beta are more diverse

25
Q

gamma:delta TCR’s are present in around what % of T cells?

A

less than 5%

26
Q

where are gamma:delta TCR’s mainly found?

A

in TISSUES

they don’t really circulate in the blood/lymph

27
Q

TCR’s recognize ______ as their ligands

A

short peptides

28
Q

what presents these short peptides to the TCR?

A

The MHC COMPLEX

29
Q

How are these short peptides that are presented to the T cell by the MHC complex generated, and what is the term for this?

A

these peptides are generated from the degradation of pathogen proteins.

this is called ANTIGEN PROCESSING

30
Q

What does MHC stand for

A

major histocompatibility complex

31
Q

“TCR can only bind antigenic peptide when peptide is bound to MHC proteins”

what is the term for this?

A

antigen presentation

32
Q

what is the name of the cell that presents the peptide/MHC complex to the TCR?

A

APC —- professional Antigen-Presenting Cell

33
Q

what are some examples of professional APC’s (antigen-presenting cell)

A

B cells, macrophages, and dendritic cells

34
Q

MHC molecules can only get to the surface of the cell when….

A

it is bound to peptide

35
Q

Each MHC molecule can bind how many peptides?

A

ONLY ONE

36
Q

What are the 2 types of MHC molecules and explain the difference between them

A

MHC Class 1
MHC Class 2

MHC Class 1 contains an accessory protein called Beta-2 microglobulin. it recognizes INTRACELLULAR PATHOGENS

MHC class 2 does NOT have an accessory protein. it binds EXTRACELLULAR PATHOGENS

37
Q

MHC Class 1 binds peptide antigen in the…..

A

ER

38
Q

MHC class 1 presents the peptide to which cells?

A

presents INTRACELLULAR PATHOGENS to cytotoxic T cells (CD8+)

39
Q

MHC Class 2 presents the peptide to which cells?

A

MHC class 2 presents EXTRACELLULAR PATHOGENS to CD4+ T cells

40
Q

MHC Class 2 binds peptide antigen where?

A

in endosomes

41
Q

what is the purpose of CD8+ T cells?

A

cytotoxic T cells that kill infected cells

42
Q

what is the purpose of CD4+ T cells?

A

helper T cells that activate macrophages to enhance phagocytosis and cytokine/chemokine production

43
Q

Which T cell stimulates B cells to promote affinity maturation of antibodies?

A

CD4+ T cells

44
Q

HIV selectively infects ____ T cells

A

CD4+

45
Q

what are TCR coreceptors?

A

CD4 and CD8

46
Q

If a T cell is contacting a virus-infected cell, what type of T cell is it and what class of MHC presented the antigen?

A

antigen was presented by MHC Class 1 and CD8+ T cell made contact

47
Q

T cells function by making ______ with other cells and inducing them to change

A

CONTACT

48
Q
A

Immunology Final (12 decks)

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