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32 Cards in this Set
- Front
- Back
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Define antigen
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Any substance that may be specifically bound by an antibody molecule or a B or T cell receptor
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What is Antisera?
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the fluid component of clotted blood from an immune individual that contains antibodies against an antigen
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Define immunogen
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Antigen that stimulates an immune response
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Describe the characteristics of a good immunogen:
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- size: immunogens are usually big i.e. greater than 10,000 daltons
- composition: complex: protein, glycoproteins, polysaccharides - Foreign |
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Define haptens
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Antigenic determinants that bind to effector cells, but do not activate them
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Define Pathogen Associated Molecular Patterns (PAMPS)
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Conserved molecules produced only by microbes and not by host organisms, such as LPS in gram neg bacteria
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Define adjuvants
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Substances used to enhance the immune response to any immunogen by delaying release of antigen
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Antigens (immunogens) express:
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Antigenic determinants (epitopes) which are specific and often cross-reactive
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What are the compositions of some common adjuvants?
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Oil in water, with mycobacteria, aluminum hydroxide gel, matrix of lipid micelles
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What are Antigenic determinants aka Epitopes?
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the portion of an antigenic molecule that is bound by an antibody (or T-cell receptor)
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Define antibodies
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A class of heterogeneous serum glycoproteins that are 82-96% protein, 4-18% carbohydrate
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Which antibodies are in the gamma fraction of serum? The beta fraction of serum?
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Gamma: IgG
Beta: IgM and IgA |
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How are an antibody’s H and L chains joined?
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covalent S-S bonds
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What determines the antibody-combining site?
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H and L chains together determine the antibody-combining site
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The enzyme papain breaks antibodies into:
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2 Fab (fragment antigen binding) fragments and 1 Fc (fragment crystallizable) fragment
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The disease where one immunoglobulin-producing B cell divides over and over resulting in large quantities of homogenous immunoglobulins is known as:
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Multiple myeloma
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What are the five classes of immunoglobulins
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IgM, IgG, IgA, IgD, IgE
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In man, how many subclasses does IgG have?
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4
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How many subclasses does IgA have?
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2
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Define allotypes
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Inherited differences on Ig molecules, not associated with the antibody-combining site
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Define idiotypes
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Unique structures on a single antibody molecule which represent a unique amino acid sequence in or close to the antibody combining site
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What are the characteristics of the hinge region
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High in proline, contains most of the cysteines involved in disulfide bonds; important in flexibility of the molecule
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What regions can both light and heavy chains be divided into?
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both heavy and light chains can be divided into a variable region (V) and a constant region (C)
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What are antibody domains?
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domains are the fundamental units of the antibody
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How many domains does the IgG monomer contain?
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12, each ~110aa long and contains an intrachain disulfide bond. These domains are the fundamental units of the immunoglobulin molecule
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Where would you find antigen contacting residues?
What are framework residues? |
- in Hypervariable regions (aka Complementarity Determining Regions CDR)
- less variable regions |
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Characteristics of IgG
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Systemic immunity (Peripheral immune system). Major constituent of serum. Only class of antibody that can cross placenta; therefore, important in passive immunity of the neonate
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Characteristics of IgA.
How is IgA the only Ig that can become secretory? |
- Mucosal Immunity (Mucosal immune system). Body secretions. IgA1 in serum, IgA2 in secrections
- Contains a secretory piece that is synthesized by epithelial cells that line the intestine |
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Characteristics of IgM
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Macroglobulin; 12% carbohydrate; occurs as pentamer, no hinge region; monomer on the cell surface of B cells (antigen-specific receptor); most efficient class to bind the serum ptn complement
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Characteristics of IgD
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Acts as an antigen-specific receptor on B cells
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Characteristics of IgE
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Responsible for immediate hypersensitivity and anaphylaxis; binds to receptor on Mast cells
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What would enzyme pepsin do to the structure of antibody?
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- forms two Fab (fragment antigen binding) fragments, Fc (fragment crystallizable) fragments disintegrate
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