PCB 4233 - EXAM 1 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026

PCB 4233 - EXAM 1 QUESTIONS ANSWERED CORRECTLY LATEST UPDATE 2026 Fill in the Blank (picture of APC + T cell) - Answers [a] APC [b] T cell [c] MHC [d] TCR [e] peptide [f] antigenic peptide [g] variable region [h] constant region [i,j] CDRs For panels a and b in Figure below, identify the most likely component(s) of the immune response (which branch of the immune system) indicated by the red arrow: *both pictures are graphs with 1 difference in x-axis [*aa*] x = time (days) [*bb*] x = time (weeks) - Answers [*aa*] innate [*bb*] adaptive Complement activation leads to - production of cytokines: fragments [*cc*] and C3a lead to local inflammation - opsonization: [*dd*] is deposited to the surface of the pathogen - formation of the [*ee*]: pore formation in the membrane of the pathogen - Answers [*cc*] C5a [*dd*] C3b [*ee*] MAC Acute phase proteins are proteins rapidly produced by the liver during infection, including [*ff*] and mannose-binding lectin for example. - Answers [*ff*] CCRPs Once an NK cell identifies a target cell, it will kill by: - Granule-dependent killing involving [*gg*] and granzymes - [*hh*]-dependent killing following binding of Fas-L/Fas receptor - Answers [*gg*] perforin [*hh*] death receptor/ligand [*ii*] is displaced from MHC class II molecule in endosomal compartments by the protein HLA-DM. - Answers [*ii*] CLIP In B cells, a very large repertoire of receptors is generated by different mechanisms: Primary gene rearrangements: - [*jj*]: Random V, D, and J segments are brought together - Junctional diversity: additional diversity provided by the enzyme [*kk*] and nuclease(s) - Answers [*jj*] BCR [*kk*] Tdt Cell membrane-destined polypeptides are translocated to the lumen of the endoplasmic reticulum, which is intriguing because the MHC class [*ll*] associated peptides are generated in the cytosol by [*mm*]. Further research revealed that the presentation of the cytosolic peptides is possible due to a family of ABC transporters, [*nn*], that mediate the ATP-dependent transport of peptides into the lumen of the endoplasmic reticulum. This transporter complex has limited specificities for the transported peptides; for example, peptides are generally [*oo*] amino acids in length and transport is biased in favor of hydrophobic residues at the carboxyl terminus. ([*oo*] describes the length of the peptides) - Answers [*ll*] 1 [*mm*] proteasome [*nn*] TAP [*oo*] 8-10 Toll-like receptor are membrane-bound pattern recognition receptors. TLR4 is found on the plasma membrane. It recognizes the bacterial wall component [*pp*] and induces signal transduction via adapter protein MyD88. Eventually, TLR4 activation leads to the activation of the transcription factor [*qq*]. - Answers [*pp*] LPS [*qq*] NFkB cGAS-STING sense the presence of [*rr*] in the cytosol, leading to the production of [*ss*] (a cytokine); while RIG-I like receptors detect [*tt*] of viral origins. - Answers [*rr*] dsDNA [*ss*] type 1 IF [*tt*] RNA In patients with lymphomas, the cancer cells invade the bone marrow and destroy the environment required for normal hematopoiesis. This leads to bone marrow failure, which disrupts the production of hematopoietic cell lineages. All of the following cell types would be affected by this EXCEPT: A. Macrophages B. T cells C. NK cells D. Muscle cells E. Dendritic cells - Answers *D. Muscle cells* How many complementarity-determining regions (CDRs) contribute to antigen biding in a Fab fragment of immunoglobulin? A. 2 B. 3 C. 4 D. 6 E. 12 - Answers *D. 6* Which of the following classes of cell surface receptors is NOT directly encoded in the germline? A. BCR B. CD4 or CD8 C. Toll-like receptors (TLRs) D. NK receptors E. none of the above - Answers *A. BCR* When tissue-resident macrophages encounter bacteria, they release cytokines that induce an inflammatory response. These cytokines act on other immune cells, to recruit them to the site of infection and to enhance their activities. In addition, these cytokines act on the endothelial cells of the blood vessel wall to: A. Secret anti-microbial peptides B. Proliferate, allowing the blood vessel to enlarge C. Increase their permeability, allowing fluid and proteins to leak into the tissue D. Solidify the tight junctions to prevent the bacteria from entering the blood E. Up-regulate microbicidal mechanisms, so they can kill bacteria - Answers *C. Increase their permeability, allowing fluid and proteins to leak into the tissue* Structurally and functionally, mannose-binding lectin (MBL) is most similar to ______________. A. Bb B. C1q C. C2a D. C3b E. C5a - Answers *B. C1q* T or F: Macrophages, neutrophils, and dendritic cells (DCs) are all phagocytes. Because of this, they can present pathogen-derived protein antigens to T cells. In this regard, they are antigen-presenting cells (APCs) as well. - Answers *False* T or F: The antibody protein has two functional domains, one for antigen binding and a second to confer specific effector functions. The former is encoded by the light chain and the latter by the heavy chain. - Answers *False* T or F: T cell receptor structure is much simpler than that of a B cell receptor. TCR mimics the Fab region in a BCR. Therefore, TCR is completely made up of variable regions, unlike BCRS which have both variable and constant regions. - Answers *False* Even when the complement cascade fails to proceed beyond generating the C3 convertase, complement activation is effective at inducing pathogen uptake and destruction. This process of immune protection is mediated by: A. Activation of complement inhibitory receptors on phagocytes that promote pathogen uptake B. Activation of soluble proteases in the serum that disrupt pathogen membranes C. Engagement of complement receptors on phagocytes by C3b which promotes phagocytosis D. Engagement of complement receptors on T cells that promotes antibody production E. Stimulation of antimicrobial peptide secretion by phagocytes - Answers *C. Engagement of complement receptors on phagocytes by C3b which promotes phagocytosis* CD8 positive T cells recognize their antigen presented by which molecules? A. BCR