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Questions and Answers
What are natural antibodies?
What are natural antibodies?
Which type of antibodies react against heterophile antigens?
Which type of antibodies react against heterophile antigens?
What is the primary function of complement-fixing antibodies?
What is the primary function of complement-fixing antibodies?
Which type of antibodies are produced in response to an immunogen?
Which type of antibodies are produced in response to an immunogen?
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What is the primary function of opsonins?
What is the primary function of opsonins?
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Which class of immunoglobulin is considered the best opsonin?
Which class of immunoglobulin is considered the best opsonin?
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What is the primary function of neutralizing antibodies?
What is the primary function of neutralizing antibodies?
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Which type of antibodies are responsible for agglutination reactions?
Which type of antibodies are responsible for agglutination reactions?
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What is the primary function of precipitins?
What is the primary function of precipitins?
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Which type of antibodies are responsible for allergic reactions?
Which type of antibodies are responsible for allergic reactions?
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Which type of antibody is primarily responsible for neutralizing toxins and viruses?
Which type of antibody is primarily responsible for neutralizing toxins and viruses?
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Which antibody class is considered the most powerful agglutinator of particulate antigens?
Which antibody class is considered the most powerful agglutinator of particulate antigens?
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Which antibody class is primarily responsible for opsonization and phagocytosis?
Which antibody class is primarily responsible for opsonization and phagocytosis?
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Which of the following antibody classes is primarily involved in immediate hypersensitivity reactions?
Which of the following antibody classes is primarily involved in immediate hypersensitivity reactions?
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Which antibody class is considered the first line of defense in mucosal immunity?
Which antibody class is considered the first line of defense in mucosal immunity?
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Which antibody class is primarily responsible for complement fixation during the primary immune response?
Which antibody class is primarily responsible for complement fixation during the primary immune response?
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Which antibody class is capable of crossing the placenta and providing passive immunity to the newborn?
Which antibody class is capable of crossing the placenta and providing passive immunity to the newborn?
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Which antibody class is primarily involved in the selection and activation of naive B cells?
Which antibody class is primarily involved in the selection and activation of naive B cells?
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Which antibody class is considered the most effective in complement fixation?
Which antibody class is considered the most effective in complement fixation?
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Which antibody class is primarily associated with immunity against polysaccharide antigens?
Which antibody class is primarily associated with immunity against polysaccharide antigens?
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Study Notes
Antibody Structure and Function
- Antibodies are specific glycoproteins referred to as immunoglobulins, found in blood plasma and many body fluids.
- Primary function is to combine with antigens, leading to bacterial or viral neutralization.
- Main humoral element of the adaptive immune response.
Immunoglobulin (Ig) Classes
- Divided into 5 major classes based on heavy chain: IgG, IgM, IgA, IgD, and IgE.
Antibody Binding Sites
- Each antibody has at least 2 identical sites that bind antigen (valence).
- Most antibodies are bivalent.
Properties of Antibodies
- Protein in nature with high molecular weight.
- Present in serum/plasma, saliva, semen, CSF, and other body fluids.
General Functions of Immunoglobulins
- Neutralize toxic substances.
- Facilitate phagocytosis and kill microbes.
- Combine with antigens on cellular surfaces, causing destruction of cells.
Classification of Antibodies
- According to sedimentation constant: IgG, IgA, IgM, IgD, and IgE.
- According to temperature: cold antibodies (IgM) and warm antibodies (IgG).
- According to occurrence: natural antibodies and immune antibodies.
- According to reaction with antigen: agglutinins, hemagglutinins, precipitins, and lysins.
Structure of Immunoglobulin
- Basic structural unit of an antibody: monomer.
- Consists of 2 heavy chains and 2 light chains.
- Heavy chain: gamma, alpha, mu, delta, and epsilon.
- Light chain: kappa and lambda.
3-Dimensional Structure of Antibodies
- Folded into compact globular subunits based on the formation of balloon-shaped loops at each domain.
Enzyme Digestion
- Papain digestion: breaks the immunoglobulin molecule in the hinge region, producing Fab and Fc fragments.
- Pepsin digestion: cleaves the heavy chain after the H-H interchain disulfide bonds, resulting in an F(ab')2 fragment.
Immunoglobulin G (IgG)
- Most predominant immunoglobulin.
- Only antibody that can pass through the placenta, providing immunity to the newborn.
- Equally distributed in different fluid compartments.
- Mediates complement fixation and opsonization.
Immunoglobulin A (IgA)
- Found in serum in small amounts but predominant in sero-mucous secretions.
- Provides immunity to the infant digestive tract.
- Acts as a first line of defense for natural immunity.
Immunoglobulin M (IgM)
- Powerful agglutinator of particulate antigen.
- Does not cross the placenta.
- First antibodies produced during an infection.
- Has 10 binding sites (pentamer).
Immunoglobulin D (IgD)
- Heat-labile immunoglobulin.
- Detected by highly sensitive assays requiring radio-labeled antisera.
- Precise biological action is not known, but may play a role in antigen-triggered lymphocyte differentiation.
Immunoglobulin E (IgE)
- Most heat-labile immunoglobulin.
- Bound to mast cells and basophils throughout the body.
- Synthesized locally by plasma cells present in the mucous membrane of the GI and respiratory tracts.
- Associated with immediate hypersensitivity reactions and immunity to certain helminthic parasites.
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Description
This quiz covers the topic outline of Antibody Structure and Function, including the Classification of Antibodies, Structure of Immunoglobulin, 3-Dimensional Structure of Antibodies, Enzyme Digestion, Immunoglobulin Classes, and Theories of Antibody Production. Explore the concepts related to antibody structure, function, and binding to various cell types.
