Brainscape's Knowledge GenomeTM

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


See full index

Immunology Test II > Antibodies and Antigens > Flashcards

Antibodies and Antigens Flashcards

1
Q

What are antibodies?

A

Circulating proteins that are produced in vertebrates in response to exposure to foreign structures known as antigens. Mediators of humoral immunity against all classes of microbes
diverse and specific

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

What term is often used interchangeably with Abs?

A

Immunoglobulins

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

How were antibodies first discovered?

A

In serum as serum molecules that provided protection against diphtheria toxin, and thus termed antitoxins

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

What are the three classes of molecules used by the adaptive immune system to bind antigens?

A

Antibodies
MHC molecules
T cell antigen receptors

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

What are antibodies only synthesized by?

A

Cells of the B lymphocyte lineage

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

What are the two forms antibodies exists as?

A

Membrane-bound antibodies on the surface of B lymphocytes: function as antigen receptors

Secreted antibodies: neutralize toxins, prevent entry and spread of pathogens, and eliminate microbes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What do membrane bound antibodies on naive B cells do?

A

When the antibody recognizes antigen, it activates these lymphocytes and initiates a humoral immune response

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

Where are secreted forms of antibodies present?

A

In the plasma, mucosal secretion, and the intersitial fluid of tissues

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

What happens to secreted antibodies during the effector phase of humoral immunity?

A

The secreted antibodies bind to antigens and trigger several effector mechanisms that eliminate the antigens

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

What are the effector properties of Abs?

A 
Toxin neutralization
Activation of complement system
Opsonization 
Immunomodulation-> reduced damage to host from inflammatory response->organized T-cell response 
Direct antibacterial activity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Define serum

A

Is the component that is neither a blood cell nor a clotting factor; It includes all proteins not used in blood clotting including antibodies

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

When blood or plasma forms a clot, where are the antibodies?

A

They remain in the residual fluid, which is called serum

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Define antiserum

A

Any serum sample that contains detectable antibody molecules that bind to a particular antigen

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

Define serology

A

The study of antibodies and their reactions with antigens

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

How many antibodies does a healthy adult human produce? What is the type of the majority of antibodies produced?

A

2 to 3 g everyday

2/3 is IgA: produced in the walls of gastrointestinal and respiratory tracts

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

How can plasma or serum proteins be physically separated?

A

By solubility characteristics into albumins and globulins

And may be more precisely separated by migration in electrophoresis

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

Plasma or serum proteins are divided into migrating groups in electrophoresis. What are the groups? Which group are most antibodies found?

A

Albumins, alpha 1-, alpha 2- (alpha1 and 2 count as one), beta-, and gamma-globulins

Most antibodies are found in the third fastest migrating group of globulins, named gamma globulins for the third letter of the Greek alphabet

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

What term is used to refer to the immunity-conferring portion of the gamma globulin fraction?

A

Immunoglobulin

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

How does each antibody differ?

A

All antibody molecules share the same basic structural characteristics but display variability in the regions that bind antigens
The effector functions and common physiochemical properties are associated with the non-antigen binding portion-few variations

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

An antibody molecule has a symmetric core structure composed of what?

A

Two identical light (L) chains and two identical heavy (H) chains
=four polypeptide chains

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

The repeating homologous units in both the light chains and heavy chains fold independently in a globular motif called what?

A

Ig domain

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

What does an Ig domain contain?

A

Two layers of beta-pleated sheets held together by a disulfide bridge

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

Both H and L chains have ________ every 90 amino acid residues, which creates _________ domains, of 110 amino acids

A

Intrachain disulfide bridges

polypeptide loops

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

What are the antigen-binding sites formed by?

A

Juxtaposition of VL and VH domains

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

ABS have a basic unit of how many polypeptide chains?

A

4

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

What are the two light (L) chains and heavy (H) chains bound together by?

A

Covalent disulfide bridges as well as by noncovalent interactions

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

Abs can be proteolytically cleaved to yield what?

A

two Fab fragments and an Fc fragment

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

What are both H and L-chains divided into?

A

V and C regions

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

How many domains are in the V and C regions of heavy chains?

A

V region is composed of one Ig domain and the C region is composed of three or four Ig domains

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

How many domains make up the V and C regions of light chains?

A

Each light chain is composed of one V region Ig domain and one C region Ig domain

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

What regions participate in antigen recognition and binding?

A

V regions

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

What regions participate in determining the fate of the Ag and mediate effector functions?

A

C regions

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

Paired VL and VH domains retain the ability to bind antigen and are called ______ fragment

A

Fab

VL-CL associated with VH-CH1

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

Two identical disulfide-linked peptides, each containing the heavy chain CH2 and CH3 domains have the propensity to self-associate and to crystallize into a lattice and are called ____ fragment

A

Fc (fragment, crystallizable)

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

There are five different kinds of H-chains referred to as what?

A

γ, δ, α, μ and ε

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

What type of H-chain determines IgM?

A

μ

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

What type of H-chain determines IgD?

A

δ

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What type of H-chain determines IgG?

A

γ

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

What type of H-chain determines IgE?

A

ε

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

What type of H-chain determines IgA?

A

α

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

What are the two types of L-chains that have a MW of 23 kDa each?

A

κ and λ

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

Each Ab unit can have only (fill in blank) but not both

A

Only κ or λ L-chains

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

The domains of the V and C regions are referred to as what?

A

VH, VL, CH1, CH2, CH3 etc

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What do heavy chain C regions end in?

A

Tail pieces

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

True or False?

The location of complement - and Fc receptor-binding sites within the heavy chain constant regions are accurate

A

False: they are approximations

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

Compared to a secreted IgG, membrane-bound IgM on B cells have ____ more CH domain(s) than IgG has

A

One

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

Membrane-bound IgM on B cells have C-terminal ________ and ______ portions that anchor the molecule in the plasma membrane

A

Transmembrane and cytoplasmic portions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

When papain is used with IgG, the enzyme acts on what region?

A

It cleaves at the hinge region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What does papain digestion allow?

A

THe separation of two Fab fragments and complement- and Fc receptors-binding the Fc fragment

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

Where does pepsin cleave IgG?

A

Distal to the hinge region

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What does pepsin generate from IgG?

A

A single bivalent antigen-binding fragment, F(ab’)2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How can Abs bind to both widely spaced cell surface determinants and closely spaced cell surface determinants?

A

Because the hinge region allows flexibility between the CH1 and CH2 domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

A large group of cell surface and soluble proteins that are involved in the _____, ______, or ______ processes of cells belongs to the immunoglobulin superfamily.

A

recognition, binding, or adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What are 6 examples of Ig superfamily proteins in the immune system?

A 
membrane-bound IgG molecule
T cell receptor; TCR
MHC class I molecule
CD4 coreceptor of T cells
CD28: costimulatory receptor on T cells
Adhesion molecule ICAM-I
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

Proteins that contain domains with an Ig fold structure (two adjacent beta-pleated sheets held together by a disulfide bridge) belong to what family?

A

Ig superfamily

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

Most of the sequence differences and variability among different antibodies are confined to what?

A

Three short stretches in the V region of the heavy chain and three stretches in the V region of the light chain

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What are segments of the greatest diversity known as?

A

Hypervariable regions; also called complementarity-determining regions (CDRs)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

How many CDRs are in the Ag-binding site of T cell receptors?

A

Three CDRs in V-alpha and three CDRs in V beta domains

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What types of Ag may be bound to immunoglobulins?

A

Proteins, lipids, polysaccharides and small chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

What types of Ag may be bound to T cell receptors?

A

Peptide-MHC complexes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

What antigenic determinants are recognized by immunoglobulins?

A

Linear and conformational determinants of various macromolecules and chemicals

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What antigenic determinants are recognized by T cell receptors?

A

Linear determinants; only 2 or 3 aa residues of a peptide bound to an MHC molecules

63
Q

What is immunoglobulins affinity of Ag binding?

A

Kd 10^-7 -10^-11 M

64
Q

what is the T cell receptor affinity of Ag binding?

A

Kd 10^-5 -10^-7 M

65
Q

What is the on-rate/off-rate of immunoglobulin?

A

Rapid on-rate, variable off-rate

66
Q

What is the on-rate/off-rate of T cell receptors?

A

Slow on-rate, slow off-rate

67
Q

Kd stands for:

A

Dissociation constant

68
Q

Which CDRs are the most variable?

A

The CDR3s of both the VH segment and VL segment

69
Q

What are loops that protrude from the surface of the two Ig V domains and in combination create an Ag-binding region

A

They are CDRs from the H and L chain

70
Q

Each domain is composed of two ________ strands, to form two _________ held together by a disulfide bond

A

antiparallel beta

beta-pleated

71
Q

Define immunogens

A

Molecules that stimulate immune responses

72
Q

Immunologists commonly attach multiple copies of small molecules to a protein or polysaccharide before immunization. This combo is called what?

A

The hapten-carrier complex
Hapten: small chemical
Carrier: large molecule

73
Q

Antibodies bind to only a portion of a macromolecule. This portion is called what?

A

Determinant or epitope

74
Q

Define polyvalency/multivalency

A

The presence of multiple identical determinants in an antigen

75
Q

Explain conformational determinant

A

Conformational determinants are formed by amino acid residues that are not in a sequence but become spatially juxtaposed in the folded protein. If the protein is denatured, then the determinant is lost

76
Q

Explain linear determinant

A

Epitopes formed by several adjacent amino acid residues.
If linear determinants appear on the external surface of a native folded protein, then they may be accessible to antibodies. Also accessible to Igs in denatured protein
The linear determinant may be inaccessible if folded in the protein. Ig can bind to determinant in denatured protein only

77
Q

Proteins may be subjected to modifications such as glycosylation, phosphorylation, ubiquitination, acetylation, and proteolysis. These modifications, by altering the structure of the protein, can produce new epitopes called what?

A

neoantigenic determinants

78
Q

The strength of the binding between a single combining site of an antibody and an epitope of an antigen is called:

A

affinity of the antibody

79
Q

The tightness of Ag-Ab binding is called:

A

affinity

80
Q

Different Abs vary in their _____ to the same Ag determinant

A

affinity

81
Q

What indicates how easy it is to separate an antigen-antibody complex into its constituents?

A

Dissociation constant (Kd)

82
Q

The higher the binding constant the (more/less) likely the Ab is to dissociate from Ag?

A

Less

83
Q

The smaller the Kd the (stronger/weaker) the affinity interaction

A

Stronger

84
Q

Abs formed in the primary response soon after the injection of Antigens are generally of (higher/lower) affinity?

A

Lower

85
Q

Abs produced by a memory response have (higher/lower) affinity than those in a primary response

A

higher

86
Q

The association constant of memory Abs are _____ times higher

A

1000

87
Q

When is the affinity of an Ab critical?

A

When the Ag is a toxin or virus and must be neutralized rapidly

88
Q

The valence of an Ab is:

A

The maximum number of antigenic determinants with which it can react

89
Q

What is the valence of IgG?

A

Contains two Fab regions and can bind two molecules of Ag or two identical sites on the same particle, thus have a valence of two

90
Q

What is important for binding affinity because it can dramatically increase the tightness of binding of the Ab to Ags?

A

valence

91
Q

What is the valence of IgM?

A

10

92
Q

Define advidity

A

The combined effect that results from synergy of the binding strengths of each binding site

93
Q

What can cause an Ab with a low affinity for Ag determinant to be extremely effective in neutralizing a microorganism?

A

IgM for example has a low affinity but has a large number of binding sites (larger valence) and thus can produce a high-adviity interaction

94
Q

Give an example of a monovalent, bivalent, and polyvalent Ab

A

mono- one Fab (IgG binding to only one antigen determinant)
Bivalent-IgG
Polyvalent - IgM

95
Q

The earliest cell in the B lymphocyte lineage that produces Ig polypeptides synthesizes the membrane form of the u heavy chain. This cell is called:

A

pre-B cell

96
Q

What stage of B cells produce κ or λ light chains, which associate with u proteins to form IgM molecules?

A

Immature and mature B cells

97
Q

What B cells express membrane forms of IgM and IgD?

A

Mature

98
Q

What stage of B cells have increased production of the secreted form of Ig relative to the membrane form and have expression of Ig heavy chain isotypes other than IgM and IgD, called heavy chain isotype switching?

A

Activated B cells

99
Q

What process results in an increase in the average binding affinity of antibodies for an antigen as a humoral immune response evolves?

A

Affinity maturation

100
Q

What are the three types of affinity maturation?

A

Mutation in V regions: changes in fine specificity without changes in C region
Switch from membrane bound to secreted antibodies
Isotype switching: C regions change without changes in the V region

101
Q

Different ______ have different biological properties and can _____ the body through different routes such as _________.

A

Microbes
enter
Ex. skin, GI tract, respiratory tract, and genitourinary tract

102
Q

The five different Ab classes and subclasses may have likely evolved to do what?

A

Facilitate protection against microbes entering at the different sites of entry

103
Q

IgA is most common for what role?

A

mucosal secretions

104
Q

IgM is mainly found where?

A

The plasma

105
Q

Where is IgE absorbed?

A

on the surface of mast cells

106
Q

Which antibody penetrates deeper into the tissue?

A

IgG

107
Q

Where are IgG found?

A

In both vascular and extravascular spaces as well as in secretions

108
Q

What is the MW of IgG?

A

150 kDa

109
Q

What is the most abundant immunoglobulin in the blood?

A

IgG

110
Q

What Ig proves the bulk of immunity to most bloodborne pathogens?

A

IgG

111
Q

What is the only Ab class to cross the placenta to provide passive humoral immunity to the developing fetus and to the infant on its birth?

A

IgG

112
Q

What chains do IgG have?

A

Two heavy γ chains with either two κ or two λ light chains

113
Q

What are the four subclasses of IgG?

A

IgG1, IgG2, IgG3, IgG4

114
Q

How do subclasses of IgG differ?

A

Slightly different sequences in their H-chains that results in differences in their functional activities

115
Q

What epithelial cell surface receptor is present in the placenta?

A

The receptor for Fc regions (FCRn) of maternal IgG

116
Q

What transfers maternal IgG to the fetal circulation?

A

FCRn

117
Q

What provides important protection prior to the generation of immunocompetence in the fetus?

A

Maternal IgG transferred to fetus

118
Q

How long does the Maternal IgG protect the fetus? Why?

A

It provides protection beyond the fetal stage to neonate. It takes some weeks following birth before the transferred IgG is eventually all catabolized

119
Q

What Ig is the major Ig present in external secretions such as colostrum, milk, and saliva where it exists as a 420 kDa dimer?

A

IgA

120
Q

What chains do secreted IgA have?

A

κ or λ L-chains and the H α chain

Two other polypeptide chains (1) secretory component (SC) and (2) J-chain (joining chain)

121
Q

What part of IgA is part of the poly-Ig receptor involved in the transepithelial transport of exocrine IgA and stabilizes IgA against proteolytic degradation?

A

SC

122
Q

What are the two Ig units composing secretory IgA held together by?

A

The J-chain through disulfide bridges

123
Q

Where are most IgA synthesized?

A

Locally by plasma cells in mammary and salivary glands and along the respiratory, GI and GU tracts

124
Q

What is the first line of defense against microbial invaders at mucosal surfaces?

A

IgA

125
Q

What is the structure and MW of IgA in serum?

A

Exists as a 170 kDa, four polypeptide (two L and two H) chain protein

126
Q

What is the first Ab produced by a B cell?

A

IgM

127
Q

What initially acts as a BCR for B cells?

A

IgM

128
Q

How is IgM on B cells expressed as?

A

Four-chain unit - two μ H-chains and two L- chains

129
Q

What is blood IgM composed of?

A

four-chain units held together by disulfide bridges

130
Q

Involving IgM, what initiates the polymerization of the subunits during secretion from a plasma cell?

A

J-chain

131
Q

IgM is found primarily where and why?

A

In the bloodstream because it is a big molecule (900 kDa)

132
Q

What are of particular importance BEFORE sufficient quantities of IgG have been synthesized?

A

IgM

133
Q

The overall avidity of an IgM is quite (high/low)

A

High

134
Q

What Ig is present in low quantities in the circulation (0.3 mg/ml in adult serum)?

A

IgD

135
Q

What Ig has the primary function as an Ag receptor on B lymphocytes, but is probably also involved in regulating B cell function when it encounters Ag?

A

IgD

136
Q

What Igs can be both expressed on B cells and are both specific for the same Ag?

A

IgM and IgD

137
Q

When IgM and IgD expressed on a B cell interact with an Ag for which they are specific, what happens to the Ag?

A

The Ag is internalized, and processed and presented to T helper cells

138
Q

What happens to B cells activated by B cell receptors?

A

The B cell proliferate and differentiate into plasma cells, thus initiating the development of a humoral immune response

139
Q

What Ig is present in the serum at very low levels and plays a significant role in enhancing acute inflammation?

A

IgE

140
Q

What Ig aids in protection from infection by worms and in allergic reactions?

A

IgE

141
Q

Ab-mediated allergy is predominantly associated with what Ig?

A

IgE

142
Q

What receptors bind to IgE that are specific for the Fc region of IgE?

A

The receptors on mast cells

143
Q

When an antigen is reintroduced to a “sensitized” mast cell, what follows?

A

The antigen binds to the IgE molecule on the mast cell and triggers the release of mediators

144
Q

What Ig is an important component of immediate hypersensitivity syndromes such as hay fever and asthma?

A

IgE

145
Q

How are hybrid cells created?

A

(1) splenocytes from a mouse that has been immunized with a known Ag are isolated.
(2) With the help of polyethylene glycol, isolated cells are fused with myeloma cells to form hybrid cells

146
Q

What are myeloma cells?

A

A cancer of plasma cells: they have immortalized properties but DO NOT secrete its own Ig

147
Q

What do myeloma cells lack?

A

HGPRT used for purine salvage pathway in most cells.

148
Q

Why do myeloma cells die in HAT medium?

A

Because the aminopterin (A) blocks de novo purine synthesis. Myeloma cells lack the HGPRT to use the alternative salvage pathway and therefore die bc they depend solely on de nova.

149
Q

Why do B cells in HAT medium survive?

A

Because even though the de novo pathway is blocked, the B cells have the enzyme HGPRT and use the salvage pathway

150
Q

Why do B cells medium eventually die?

A

Because B cells will die because of there inherent nature in 7-10 days

151
Q

What happens after the hybrid cells are created?

A

They are placed in a selection medium (HAT) that permits the survival of only immortalized hybrids. The myeloma cells and the B cells do not survive and only the hybrid cells survive in HAT medium

152
Q

What does the HAT medium include?

A

Hypoxanthine, aminopterin, and thymidine

153
Q

What does HGPRT stand for?

A

hypoxanthine-guanine phosphoribosyl transferase

Immunology Test II (7 decks)

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