Zusammenfassung der Ressource
Frage 1
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All of the following are part of Fab region of Ig except?
Frage 2
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VH and VL determines the idiotype and CH2 and CH3 determine the isotype of Ig
Frage 3
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Antigen Binding site
Antworten
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Specificity is determined by hypervariable regions within the variable domain
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Each variable region has 3 hypervariable regions called complementary determining regions (CDRs)
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An antigen binding site is composed of 3 light chain CDRs and 3 heavy chain CDRs
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All of the above are true
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None of the above
Frage 4
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Isotypic : constant domain, present in all individuals of a species
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Allotypic: constant domain; different alleles within a species
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Idotypic: antigen binding site
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all of the above are true
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1&2 are true
Frage 5
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Antibodies interact with molecules by the Fc receptors (constant region)
Frage 6
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Regarding different classes of Ig a
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IgG - Monomer - circulating - Most abundant in serum - crosses transplacentally via brambell receptor
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IgM - Pentamer - Surface of B cells or circulating - Ag receptor on B cell - First class of Ab released by B cells during primary response
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IgA - Monomer - Surface of B cells - Important for B cell activation - Co-expressed with IgM on B cells due to differential RNA splicing
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IgD - circulating monomer, secreted dimer - circulating in plasma or secreted in saliva ,tears, milk etc - protects mucosal surfaces
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IgE - Monomer - circulating or cell bound - found in mast cells and basophils - High affinity IgE receptors binds in the absence of Ag
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All are correct
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1,2,5 are correct
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3,4 are correct
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All are wrong
Frage 7
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Regarding Pro-B cell all are true except?
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No Ig is expressed
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Recombination Signal Sequences (RSS) & 12/23 rule regulate arrangement & ensure that proper joining occurs: D-J --> V-DJ
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RAG1/RAG2 recognised and binds to Il-7R
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Palindromic nucleotide addition at hairpin loop formation by DNA polymerase
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Non-template nucleotide addition at hairpin loop formation by TdT
Frage 8
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Regarding Pre-B cell
Antworten
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IgM expressed
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Allelic Exclusion: RAG1/RAG2 is repressed to stop VDJ rearrangement of H locus
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RAG1/RAG2 is re-expressed for VJ rearrangement - Somatic Recombination - of each daughter cell's L chain
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Kappa light chain recombines 1st
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all of the above are correct
Frage 9
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Immature B cell - all are true except
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IgG expressed
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Negative Selection for Tolerance - Immature B cell with no self reaction will continue on to maturity and leave the bone marrow
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Light chain rearranges for a chance to make BCR with new specificity
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Immature B cell binds multivalent self-antigen and fails receptor editing --> Clonal deletion (apoptosis)
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mmature B cells bind soluble self-antigen --> Clonal anergy
Frage 10
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Mature B cell express IgM + IgD due to differential RNA splicing
Frage 11
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CD21 co-receptor binds Fc of Ig (ITIM) - positive co-receptor --> activation
FcyR binds to C3d - negative co-receptor --> no activation
Frage 12
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Following is the sequence of events 1st T_B cell interaction - all of the following are true except?
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Antigen activated B cell (APC) migrates toward T-B boundary and present antigen by MHC II to CD4+ Helper T cell
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CD40 activates T Helper to express CD40-L and cytokines
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CD40-CD40-L bind and T Helper releases cytokines toward B cell
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Mutated CD40-L results in X-Linked agammaglobulinemia
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Proliferation of activated B cell to form germinal centers (Clonal expansion)
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AID (Activation Induced Deaminase) inserts point mutations in the variable regions of BCR for diversification of BCR
Frage 13
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All of the following regarding 2nd T-B cell interaction are true except?
Antworten
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Class/Isotypic Switching : The constant region of the heavy chain undergoes change of Ig Isotype but the selected variable region stays the same maintaining antigenic specificity and affinity
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Isotype is determined by cytokines released from Helper T cell
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Enables the same assembled Vh exon to be associated with different CH genes in the course of an immune response thus increasing the divrsity of Ig function
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Il-4 secreting T cell stimulate Plasma cell production and Il-10 secreting T cell stimulate memory B cell production
Frage 14
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Thymus independent response the antigens are polysaccharides and the antibody made is always IgM because there is no class switching, no affinity maturation and no memory cell formation
Frage 15
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MHC Class I is expressed on the surface of all nucleated cells including RBC
Frage 16
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Endogenous pathway MHC I and Exogenous pathway MHC II
Frage 17
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Antign processing is proteolytic deradation of proteins into peptides of a suitable size for binding to MHC
Antigen Presentation - actual display of the processed peptide bound to MHC molecules on the surgace of an APC or target cell
Frage 18
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T cell recognize non linear and conformational determinants
Frage 19
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Dendritic cells are exception to the rule - Cross presentation allows exogenous proteins to be presented on MHC I and endogenous proteins to be presented by MHC II by autophagy
Frage 20
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Viral proteins interfere with MHC I
Frage 21
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Intracellular bacteria evade MHC II by
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Escape endosomes
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Neutralize endosome acidification
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Block fusion with lysosomes
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Sequesters MHC II molecules after vesicle fusion
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All of the above