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Biochem Test 1
Immunoglobulins
| Question | Answer |
|---|---|
| produced in response to invasion by foreign compounds (antigens) | Antibodies |
| Antibody binding to an antigen initiates a process that | eliminates the foreign substance |
| Antigens may have several antigenic determinant regions in them called | epitopes |
| in what cases do antibodies recognize own structure? | rheumatoid arthritis, type 1 diabetes |
| Immunoglobulin molecules consist of | four polypeptide chains, two identical copies of two different chains, designated L and H. |
| four chains are covalently interconnected by | disulfide bonds |
| gives the molecule flexibility upon antigen binding and where heavy chains are interconnected | hinge region |
| the most common immunoglobulin | IgG |
| Why IgG 3D struct instead of quaternary? | b/c quaternary structs require noncovalent bonds, and IgG has covalent bonds (the disulfide bonds that hold the L&H together) |
| how many domains of the constant C region are on the H chain? L chain? | 3 - H 1 - L |
| N-terminal sequences are | variable (V) regions and are designated VH and VL |
| Within the V regions, certain segments are hypervariable, called | complementarity-determining regions (CDRs) |
| form the antigen binding sites | complementarity-determining regions (CDRs) |
| variable regions give the antibody its | specificity |
| N terminal half of the L chains and the N terminal quarter of the H chains are | highly variable between different antibody molecules |
| C-terminal three quarters of the H chains and the C terminal half of the L chains are | homologous in sequence with the other H or L chains of the same class of antibodies |
| these regions have a homologous primary structure | constant (C) regions |
| these regions determine the antibody class | CH regions |
| binding site for complement proteins | CH regions |
| site necessary for antibodies to cross the placental membrane | CH regions |
| what carries specificity in the hypervariable region of variable domain in L and H? | random coils |
| each chain of an antibody molecule has a repeating pattern of structure, called | domains |
| how many domains in H-chain? L-chain? | H: four domains, VH region and three CH regions L: two domains, VL region and CL region |
| Each domain folds into a structure built by | antiparallel β-pleated sheets |
| domain folds built by antiparallel β strands generate a motif known as | all-beta immunoglobulin fold |
| each domain is stabilized and cross-linked by | s-s and random coils |
| Ig is modified by | carbohydrates |
| what does protein A do? | precipitate Antibody to detect and quantify |
| what's Clq? | complement cascade that plays role in eliminating Ag |
| describe series from antigen to complement | 1) Ag binds Ab 2) exposes C1, allows C1 to bind Ab 3) activates macrophages |
| function of Antibodies? | recognition and binding of foreign molecules and the initiation of their removal |
| When antibodies bind to antigens, small changes in conformation occur where? | CDRs (complement determining regions) |
| Conformation change in CDR (located in V-region) caused by Ag binding to Ab, cause conformation change where? | C-terminal region |
| when c-terminal region changes conformation, what happens next? | exposes complement binding site at Fc region and allow binding of C1 complex, activates complement system, and lyses cell membrane |
| complement proteins are precursors of | proteolytic enzymes |
| The major role of the complement system is to | generate opsonins |
| proteins that stimulate phagocytosis by neutrophils and macrophages | opsonins |
| major opsonin that bind to specific receptors on the macrophage cell surface | C3b |
| Patients with inherited deficiency of C3 (an opsonin) are subject to | repeated bacterial infections |
| Characteristics of each class are due to differences in | heavy chains. |
| H chains γ occur in which Ig? | IgG |
| H chains α occur in which Ig? | IgA |
| H chains δ occur in which Ig? | IgD |
| H chains ε occur in which Ig? | IgE |
| H chains μ occur in which Ig? | IgM |
| how many classes of H chains are there? | five |
| Two types of L chains are? | lambda (λ) and kappa (κ) |
| which Ig classes are most prominent in immune response in blood? | IgG and IgM |
| these Ig classes are monomers (LH)2 | IgAs, IgDs, IgEs and IgGs |
| Which Ig class is in seromucosal secretions are covalently linked dimeric structures ((LH)2)2 | IgA |
| what keeps dimers and pentamers in IgA and IgM together? | J-chain |
| IgA's seromucosal secretions are found in? | Mother's milk, saliva, eyes brochial, nasal, intestinal secretions |
| function of seromucosal secretions? | fight Ag before they get through epithelial cells and body |
| This class of Ig are pentamers ((LH)2)5 | IgMs |
| Biosynthesis of a specific IgG in significant levels takes about how many days after exposure to a new antigen? | 10 days |
| Which Ig class is made first and faster and serve as the first line of defense until IgGs are made | IgMs |
| How many weeks after initial Ag contact is IgG synthesized? | 2 weeks |
| They are the initial defense against viral and bacterial pathogens prior to entry into plasma or internal space | IgA class of immunoglobulins |
| neutralize viruses, toxins and block bacterial adherence on mucosal surfaces | IgAs |
| They are the first antibodies elicited in significant quantities on exposure to foreign antigen | IgM class |
| This class of Ig found in many external secretions but at lower levels than IgA | IgM |
| this Ig class promotes phagocytosis of microorganisms by macrophages and polymorphonuclear leukocytes, and is a potent activator of the complement system | IgM |
| what is order of Ig classes from most concentrated in plasma to least? | IgG, IgA, IgM, IgD, IgE |
| This is the only antibody that is able to cross the placenta | IgG |
| this class can secrete to breast milk, thus provides immunity to newborns | IgG |
| It serves as antigen receptor on lymphocytes and participates in their activation. | IgD |
| mediates immediate hypersensitivity reactions, thus plays a role in allergic responses such as anaphylactic shock, hay fever and asthma. | IgE |
| is also considered an anti-parasite antibody | IgE |
| selective IgA deficiency results in | recurrent infection of sinus and the respiratory tract |
| An immunizing vaccine can consist of | killed bacterial cells, inactivated viruses, killed parasites, a nonvirulent form of live bacterium related to a virulent bacterium or denatured bacterial toxin or recombinant protein |
| Antigens not only cause differentiation of lymphoid cells so they produce antibody but also cause | differentiation of some of the cells into memory cells. |
| they do not secrete antibody but place antibody on their outer surface and serve as radar | Memory cells |
| reduces the time needed for defense and increases the concentration of antigen specific antibody | memory cells |
| what's Multiple myeloma | uncontrolled proliferation of plasma cells and the synthesis of a homogenous gamma globulin, called M-protein |
| Only one type of immunoglobulin is produced with one type of light chain is overproduced | monoclonal gammopathies |
| monoclonal gammopathies: plasma and urine electrophoreses show typical single peak in the | gamma globulin |
| a doublet of a kappa or lambda light chain | Bence- Jones protein |
| light chain secreted in the urine Multiple myeloma patient is | Bence- Jones protein (doublet of a kappa or lambda light chain) |
| what are the clinical manifestations of multiple myeloma? | Bone fractures, Bleeding, Chronic renal failure, anemia, granulocytopenia and thrombocytopenia |
Created by:
rosejames05
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