54. Antibodies - definition, structure, major class’s and functions. Flashcards

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1
Q

Antibodies are glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodies - triggered by antigens

A

Antibodies are glycoprotein molecules that are produced by plasma cells in response to an immunogen and which function as antibodies - triggered by antigens

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2
Q

Structure: heavy + light chains. Disulfide bonds (either inter-chain or intra-chain). There are variable and constant regions, as well as the hinge region. Antibodies are made of oligosaccharides. Antibodies can occur in fragments resulting in a fab and Fc part. Fab part - antigen binding, Fc part - effector functions.

A

Structure: heavy + light chains. Disulfide bonds (either inter-chain or intra-chain). There are variable and constant regions, as well as the hinge region. Antibodies are made of oligosaccharides. Antibodies can occur in fragments resulting in a fab and Fc part. Fab part - antigen binding, Fc part - effector functions.

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3
Q

Antigen-antibody reactions follow the lock and key system. Basically this concept shows the antigen is the key and the antibody is the fitting lock. Antigen-antibody reaction is held by non-covalent bonds. Non-covalent bonds keep the antigen in the antibody combining sit. Electrostatic forces, Van der Waals forces are typically the types of bonds. These reactions are reversible due to non-covalent bonds.

A

Antigen-antibody reactions follow the lock and key system. Basically this concept shows the antigen is the key and the antibody is the fitting lock. Antigen-antibody reaction is held by non-covalent bonds. Non-covalent bonds keep the antigen in the antibody combining sit. Electrostatic forces, Van der Waals forces are typically the types of bonds. These reactions are reversible due to non-covalent bonds.

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4
Q

The strength of the antigen-antibody reaction is measured by affinity and avidity .

Affinity - the strength of a single antigenic determinant and a single combining site of the antibody. (sum of attractive + repulsive forces between the two)

Avidity - measure of overall strength of binding or an antigen. Influenced by valence of both antigen and antibody

A

The strength of the antigen-antibody reaction is measured by affinity and avidity .

Affinity - the strength of a single antigenic determinant and a single combining site of the antibody. (sum of attractive + repulsive forces between the two)

Avidity - measure of overall strength of binding or an antigen. Influenced by valence of both antigen and antibody

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5
Q

Antibodies have a certain specificity - the ability of a population of antibody molecules to react with only one antigen. Antibodies can distinguish the primary, secondary, tertiary structure of the antigen + the isomeric forms of the antigen.

A

Antibodies have a certain specificity - the ability of a population of antibody molecules to react with only one antigen. Antibodies can distinguish the primary, secondary, tertiary structure of the antigen + the isomeric forms of the antigen.

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6
Q

Cross reactivity - the ability of a population of antibody molecules to react with more than one antigen. Cross reactivity occurs because the cross reacting antigen shares an epitope with the immunising antigen.

A

Cross reactivity - the ability of a population of antibody molecules to react with more than one antigen. Cross reactivity occurs because the cross reacting antigen shares an epitope with the immunising antigen.

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7
Q

Structure continued: antibodies have different domains: the V1 + C1 domain and the Vh and Ch1-Ch3 (or Ch4) domain.

A

Structure continued: antibodies have different domains: the V1 + C1 domain and the Vh and Ch1-Ch3 (or Ch4) domain.

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8
Q

Antibodies are classified as:

  • IgG - gamma heavy chains
  • IgG1 - gamma 1 heavy chains
  • IgG2 - gamma 2 heavy chains
  • IgG3…
A

Antibodies are classified as:

  • IgG - gamma heavy chains
  • IgG1 - gamma 1 heavy chains
  • IgG2 - gamma 2 heavy chains
  • IgG3…
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9
Q

IgM - mu heavy chains

IgA - alpha heavy chains

IgD - delta heavy chains

IgE - epsilon heavy chains

A

IgM - mu heavy chains

IgA - alpha heavy chains

IgD - delta heavy chains

IgE - epsilon heavy chains

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10
Q

IgA Found in mucosal areas - gut, respiratory tract, urogenital tract
Prevents colonisation by pathogens
Found in saliva, tears and breast milk

A

IgA Found in mucosal areas - gut, respiratory tract, urogenital tract
Prevents colonisation by pathogens
Found in saliva, tears and breast milk

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11
Q

IgD Antigen receptor on B calls that havent been exposed to antigens
Activates basophils and mast cells to produce antimicrobial factors

A

IgD Antigen receptor on B calls that havent been exposed to antigens
Activates basophils and mast cells to produce antimicrobial factors

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12
Q

IgE Binds to allergens and triggers histamine release from mast cells and basophils
involved in allergy
protects against parasitic worms

A

IgE Binds to allergens and triggers histamine release from mast cells and basophils
involved in allergy
protects against parasitic worms

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13
Q

IgG Provides most of antibody-based immunity against invading pathogens.
the ONLY antibody that’s capable of crossing the placenta to give passive immunity to the
foetus

A

IgG Provides most of antibody-based immunity against invading pathogens.
the ONLY antibody that’s capable of crossing the placenta to give passive immunity to the
foetus

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14
Q

IgM Expressed on surface of B cells (monomer) and in a secreted form (pentamer) with a very high
avidity
eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there’s
sufficient IgG

A

IgM Expressed on surface of B cells (monomer) and in a secreted form (pentamer) with a very high
avidity
eliminates pathogens in the early stages of B cell mediated (humoral) immunity before there’s
sufficient IgG

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