Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

CMB2004 stage 2 > Lecture 1- 6 > Flashcards

Lecture 1- 6 Flashcards

1
Q

What must the immune system do for an effective response?

A
  • be able to recognise and respond to any invading organism
  • not over react to benign or self
  • be able to direct different effector mechanisms against different pathogens
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the features of specific/adaptive immunity?

A
  • mediated by lymphocytes (B/T cells)
  • clonally distributed receptors = recognise different pathogens
  • response takes time but memory cells are produced
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What do antibodies do?

A
  • activate the complement system = opsonisation -> classical pathway activation -> activation of effector cells
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What is the role of TCR ( T-cell receptors)?

A

recognizes peptide fragments of antigen bound to MHC expressed by APC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What is the role of BCR (B-cell receptor)?

A

membrane form of Ig that binds free antigens = secreted when B cell is activated

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the structure of antibodies?

A
  • formed from 4 polypeptides
  • 2 identical heavy chains and light chains held together by covalent and non-covalent bonds
  • 2 types of light chain = lamda and kappa
  • each chain has a variable region and a constant region
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is the function of the V and C region in antibodies?

A
  • paired variable region (V) = form 2 identical antigen-binding sites
  • constant (C) region = responsible for Ab structure and interacting with other molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What are the 5 antibody classes and how is the isotope determined?

A
  1. IgM
  2. IgD
  3. IgA
  4. IgG
  5. IgE

isotype is determined by the heavy chain (C region)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

How many domains does the H and L chain on an antibody have?

A

L chain = 2 domains
H chain = 4 or 5 domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What are antibody domains and what do the comprise of?

A

domains = patterns present in many other proteins in the immune system

comprises of two beta sheets linked by disulphide bridge

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an epitote?

A

the piece of antigen that antibodies recognise

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the characteristics of MHC class I?

A
  • expressed on all nucleated cells
  • heterodimer: alpha chain (42 kD) and b2-microglobulin (12 kD)
  • 3 different types of MHC class I molecules
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

What are the 3 MHC class I molecules?

A

HLA-A
HLA-B
HLA-C

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What are the characteristics of MHC class II?

A
  • expressed only on APC and cytokine-activated cells
  • heterodimer: alpha chain and and beta chain
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What are the 3 MHC class II molecules?

A

HLA-DP
HLA-DQ
HLA-DR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the process by which enough cells expressing receptors for the correct pathogen is known as?

A

clonal selection

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

What are the 2 chains of an antibody called?

A

heavy chain and light chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

Which part of an antibody interacts with the epitope of an antigen?

A

two identical antigen binding sites mainly CDRs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

Define the Fab and the Fc regions of an antibody?

A

Fab is (VH/CH1+ VL/CL1) domains (artificially generated with papain)

Fc is ((CH2/CH3/+ (CH4 sometimes)) x2 regions of antibody that binds to FcRs;
(also artificially generated with papain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is the antigen binding site of an antibody made up of?

A

variable domain of H and L chains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

The lamda and kappa chains form what chain of the antibody?

A

light chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How many hypervariable regions are involved with antigen binding in a single antibody molecule?

A

12

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What type of proteins are TCR?

A

heterodimeric proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are the most common T cells?

A

T cells that express gamma and delta TCRs

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What class of MHC binds smaller processed peptides?

A

Class I MHC in the endoplasmic recticulum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What are the H chain and TCRb encoded by?

A

V region encoded by 3 gene segments = V, D and J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What are the L chain and TCRa encoded by?

A

V region encoded by two gene segments: V and J

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

When and why do genes rearrange?

A

genes rearrange during B cell development to form a functional gene

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What is the gremline organisation of L and H loci in the human genome?

A

lamda light chain = one of the variable genes on the light chain locus randomly joins to the J region and then joins to constant region

kappa light chain = V region genes and J region genes randomly join together

heavy chain = take a D and J and then a gene segment and bind randomly with a B region and constant region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

Which gene segments encode the variable region of the Ig heavy chain?

A

VDJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

Which gene segments encode the variable region of the light chain of an
antibody?

A

VJ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How are the heavy (H) chain of an antibody and the beta (b) chain of the TCR
similar?

A

Similar gene fragments (VDJ)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

When does rearrangements of Ig genes occur?

A

during their development in the BM when they are termed pro and pre-B cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

Does the heavy or light chain constant region determine an antibody’s isotype?

A

heavy

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

What guides DNA rearrangement?

A

guided by special sequences flanking the V, D and J regions = recombination signal sequences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What do the recombination activating gene encode?

A

RAG-1 and RAG-2 genes encode lymphoid specific components of the recombinase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What are the 5 distinct mechanisms that allow for antibody diversity?

A
  1. Families of gene segments that re-arrange i.e. combinatorial
  2. junctional diversity (not precise joining)
  3. N region addition
  4. heavy and light chain pairing
  5. somatic hypermutation
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What is allelic exclusion?

A

In a single B cell, only one allele of H and L chain is expressed to produce a cell with specificity to a certain antibody

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What is somatic hypermutation?

A

AID acts on DNA to de-aminate cytosine to uracil = is recognised by error-prone DNA repair pathways leading to mutation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What is the difference between the arrangement of B and T cells?

A

T cells = occurs in thymus
B cells = occurs in bone marrow

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

What are the most abundant T cell receptors?

A

TCR-alpha and TCR-beta

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

How does MHC polymorphism affect their function?

A

occur in the domains that fold to form
the peptide-binding groove so will increase the no. of possible peptides that are suitable for
binding, allowing the human population to be able to bind as many different peptides as
possible

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

How do peptides end up on the surface of cells bound to MHC class I and/or class II?

A
  1. peptides from protein Ag synthesized in cytoplasm = presented by MCH class I
  2. peptides derived from exogenous Ag = presented by MCH class II
44
Q

What is TAP?

A

a component of a multi-protein assembly = peptide loading complex

45
Q

How is an antigen (Ag) processed and presented by an MHC class I molecule?

A

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

2) protein cleaved to peptides by proteasome

3) peptides transported to endoplasmic reticulum by TAPtransporter

4) peptides bind to MHC class I molecules

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

46
Q

How is an antigen processed and presented by a MHC class II molecule?

A

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

47
Q

Which gene segments encode the variable region of the TCRa chain?

A

TCRVa/TCRJa

48
Q

What does the CLIP protein do?

A

prevents peptides in ER from binding class II

49
Q

What is the role of the invariant chain?

A

prevents peptides in ER binding class II
AND targets class II to endocytic compartment

50
Q

Is the proteosome involved with MHC class I or MHC class II peptide processing?

A

MHC class I

51
Q

Do MHC class I molecules present peptides from exogenous sources?

A

class I MHC molecules present peptides derived from endogenous sources (self-peptides or viral antigens).

52
Q

What function does the protein encoded by the HLA-DM genes perform?

A

removes CLIP from MHC class II molecules allowing peptides from Ags present in the endocytic pathways to bind class II

53
Q

What type of MHC molecule do HLA-A, B and C encode?

A

MHC class I molecule

54
Q

Can a single individual express more than one type of MHC molecule on the surface of their macrophages?

A

Yes. MHC genes are co-dominantly
expressed = an APC such as a macrophage found in an MHC hetereozygous individual can express up to 12 MHC molecules (6 class I and 6 class II) at the
same time

55
Q

What is the process of B cell development?

A

develop from haematopoietic stem cells in bone marrow that express PAX5 transcription factor which involves re-arrangemnt and expression of Ig genes

56
Q

What are the steps for the formation of pre-B cell receptor?

A
  1. rearrange heavy chain first and then checked out by Vprebeta and lamda products to make sure it is a proper heavy chain = pre B cell receptor
  2. Light chain is rearranged and binds to heavy chain
  3. Becomes a proper B cell
57
Q

What is the role of the pre-B cell receptor?

A

Delivers signals to pre-B cell with no antigen requires

58
Q

What are the steps for pre-B cell receptor signals?

A
  1. signal turns off RAG-1 & RAG-2 genes
  2. 5-6 rounds of cell division
  3. surrogate light chain expression stops
  4. RAG-1 and RAG-2 turned on again
  5. L chain rearrangement starts
59
Q

Most predominant surface Ig (BCR) expressed by immature B cells?

A

IgM

60
Q

What happens to immature B cells that bind multivalent self-antigens?

A
  1. clonal deletion = cell dies by apoptosis

or

  1. receptor editing = further light chain gene rearrangements of variable regions
61
Q

If BCR expressed by immature B cell binds to self cell-surface antigen, the B cell is removed
by which type of selection?

A

deletion/negative selection

62
Q

Activated B cells in the periphery can develop into?

A

plasma cells, memory B cells

63
Q

Which Ig chain is re-arranged first?

A

heavy chain

64
Q

What is the surrogate light chain?

A

non-variable light chain-like molecule that binds
rearranged heavy chain to check heavy chain has assembled correctly

65
Q

Which gene segments get re-arranged in the heavy and light chains?

A

VDJ and VJ

66
Q

What is the difference between T-cell development and B-cell development?

A

T cell
- undergo development/selection in thymus
- alternative lineages
- rearrange ab TCR genes or gd TCR genes

67
Q

What do the RAG1 and 2 genes do and when?

A

form a complex to break B/T cell DNA to
allow gene segments to be rearranged during B/T cell development in the bone marrow (B
cells) and thymus (T cells)

68
Q

What are the steps for alpha/beta T cell development?

A
  1. re-arrange TCR genes (beta first) and express TCR
  2. acquire other markers e.g CD3, CD4 and CD8
  3. undergo positive and negative selection
69
Q

What are the Cells other than thymocytes that are present in the thymus?

A

epithelial cells and APC

70
Q

What is the pre-TCR?

A

re-TCRa protein bound to rearranged TCRb = Checks assembly of b chain

71
Q

What does the CD3 molecule do and why is it important?

A

Multi-component signalling part of TCR = leads to T cell activation following peptide/MHC antigen binding

72
Q

What type of T cells do not express CD4 or CD8 markers?

A

gamma delta T cells

73
Q

What is positive and negative selection of T cells?

A

Positive selection = TCR must recognize self MHC alleles in thymic cortex

Negative selection = TCR binds
self MHC and peptide too strongly in thymic medulla will die

74
Q

If a T cell recognises peptide and MHC I which marker does it have on its cell surface?

A

CD8

75
Q

Are the criteria for positive and negative selection of immature T cells the same?

A

Similar; both involve
ability to recognize self MHC molecules, but the affinity of TCR for peptide/MHC forms the basis of the differences

76
Q

Where do T cells and APCs contact each other?

A

T cell zone of secondary lymphoid tissues eg. LNs

77
Q

What are the two types of T cells and what are their roles?

A
  1. cytotoxic effect T cells (CD8+) = kill infected cells
  2. helper effector T cells (CD4+) = secrete cytokines
78
Q

How are APC (antigen presenting cell) activated?

A

Following the binding of PAMPs present in pathogens PRR expressed by APC will signal to induce the activation of APCs

79
Q

How do T cells get to where they need to be?

A
  1. enter the lymph node from blood via high endothelial venules
  2. move into T cell area which is rich in dendritic cells and macrophages
  3. APC present antigen and deliver other activation signals
80
Q

What is the effector role of a CD8+ T cell?

A

Cytotoxic T cell

81
Q

What are high endothelial venules?

A

Specialized vascular pathways into secondary lymphoid tissues from the blood

82
Q

What happens to a naïve T cell that is not activated in a lymph node?

A

It will leave and re-enter the blood and then re-enter the Lymph Node again

83
Q

What is a CAM?

A

surface molecule on a cell that binds another CAM on another cell to allow the cells to transiently adhere to each other

84
Q

List 3 types of cells that a T cell might interact with via a CAM

A

HEV cell, APC, infected target cell

85
Q

How do T cells contact antigen presenting cells (APCs)?

A

T cell contact APCs using CAMs

  1. TCR scans APC peptide/MHC complexes
  2. recognition = signal from TCR complex
  3. increases affinity of CAM interactions
  4. T cell divides
  5. progeny differentiate to effector cells and leave lymph node
86
Q

How many stimulatory signals are needed to activate a T cell?

A

3 (TCR, CD28, cytokine receptor)

87
Q

What is CTLA-4?

A

Co-inhibitory molecule expressed on activated T cells

88
Q

What does B7 on an APC bind to on a T cell?

A

CD28 and CTLA-4

89
Q

How are APC activated?

A

via PAMPs binding to APC’s PRR

90
Q

Why is the cytokine IL-2 important?

A

induces both CD4+ and
CD8+ T cell proliferation

91
Q

Do activated T cells express a high or low affinity IL-2 receptor on their surface?

A

high

92
Q

What are the 3 antibody functions?

A
  1. neutralisation = antibody prevents bacterial adherence
  2. opsonization = antibody promotes phagocytosis
  3. complement activation = antibody activates complement = enhance opsonization and lyses some bacteria
93
Q

What is signal 1 that induces B cell activation?

A

Ag binding BCR

94
Q

Define a TI Ag B cell response?

A

Non-switched (IgM), low affinity response usually induced by an antigen that
binds BCR and another B cell surface receptor (e.g a TLR)

95
Q

How does the delivery of signal 2 in a TD response differ from that delivered by a TI Ag?

A

TD signal (via T cell produced cytokines or their expression of CD40L) leads to B cell undergoing
somatic hypermutation and class switching

96
Q

Why are MHC class II molecules essential for a B cell
response to a TD Ag?

A

TD B cell response require CD4+ T cells which are activated via MHC class II

97
Q

What is CD40, and which cell type is it usually expressed by?

A

Signalling molecule that can provide signal 2 to a B cell (or activate a macrophage) via interaction with T cell CD40L

98
Q

What are the roles of Iga and Igb once B cells leave the bone-marrow?

A

Delivers signal 1 (Ag binding the BCR) to B cell

99
Q

What does ITAM stand for?

A

immunoreceptor tyrosine-based activation motif

100
Q

What is a centroblast and where is it found?

A

proliferating Ag-specific B cell found in dark zone of germinal centre in secondary lymphoid tissue

101
Q

What is a centrocyte and where is it found?

A

non-proliferating Ag-specific B cell found in light zone of germinal centre in secondary lymphoid tissue

102
Q

How can signal 1 be increased/enhanced?

A
  • if an antigen has activated complement cascade
  • lots of C3b
  • complement receptor 2 on B cell surface
103
Q

What are follicular T helper cells (TFH) and where are they usually found?

A

specialized CD4+ T cell sub-set found in light zone of GC that recognize peptides/MHC that centrocytes compete to present.

104
Q

How do follicular dendritic cells (FDC) differ to DC1, 2 and DC3?

A

FDC are only found in secondary lymphoid tissues and do not express MHC class II molecules = do not process and present antigen to CD4+ T cells

105
Q

Which BCR isotypes can be co-expressed by a single B cell?

A

IgM and IgD

CMB2004 stage 2 (2 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions