Q&A Hero

Q: Antibody titer can be measured by A) negative microscopy. B) agglutination. C) plate counts done after isolating the pathogen. D) polymerase chain reaction.

Q: Most drug-resistant bacteria isolated from patients contain a(n)A) R plasmid.B) T1 phage.C) reverse transcriptase.D) -lactam.

Q: Widespread antimicrobial drug resistance is usually passed by A) heterologous gene expression. B) reverse transcription. C) horizontal gene transfer. D) gene splicing.

Q: The blotting of proteins from polyacrylamide gels to nitrocellulose paper, and the subsequent identification by specific antibodies, is called a(n) ________ blot. A) Western B) Eastern C) Southern D) Northern

Q: Which of the following would be useful for treating Candida? A) an azole B) a fusion inhibitor C) a macrolide D) a nucleoside reverse transcriptase inhibitor

Q: Which of the following is a mechanism of aminoglycosides? A) inhibition of cell wall biosynthesis B) prevention of peptidoglycan crosslinking C) inhibition of DNA replication D) targeting the 30S ribosomal subunit

Q: One advantage of the fluorescent antibodies that permits disease diagnosis long before primary isolation techniques yield results is that A) cross-reactions do not occur. B) few controls are required. C) nonspecific staining does not occur. D) it may be applied directly to tissue.

Q: The first antibiotic to be characterized was aA) cephalosporin.B) quinolone.C) -lactam.D) macrolide.

Q: Latex bead agglutination tests are A) rapid and reliable tests used for the detection of certain bacteria as well as certain serum antibodies. B) inferior tests used in developing countries not having facilities for more reliable assays. C) an integral part of the EIA test procedure. D) too expensive for routine use.

Q: EMB agar preferentially selects for the growth of ________ bacteria. A) gram-positive B) gram-negative C) gram-variable D) both gram-positive and gram-negative

Q: Which of the following immunological tests would allow the specific identification of a microorganism directly in a patient specimen? A) fluorescent antibody (FA) B) radioimmunoassay (RIA) C) enzyme-linked immunosorbent assay (EIA) D) agglutination

Q: The disk-diffusion test is used for A) assessing antimicrobial activity. B) the identification of Escherichia coli. C) the identification of viral plaques. D) the detection of antigen.

Q: Some antibiotics inhibit protein synthesis by disruption of translation through interactions with the A) ribosome. B) protein. C) DNA. D) chromosome.

Q: Which type of medium typically contains an indicator dye? A) selective but not differential B) differential but not selective C) both selective and differential D) neither selective nor differential

Q: The oxygen-free gas commonly employed during anoxic incubation of a bacterial culture is a mixture of A) nitrogen and carbon dioxide. B) nitrogen and carbon monoxide. C) nitrogen and argon. D) nitrogen and hydrogen.

Q: Modified Thayer-Martin (MTM) agar A) incorporates antibiotics into the medium. B) enhances the growth of normal flora. C) prevents the growth of Neisseria gonorrhoeae, but promotes the growth of Neisseria meningitidis. D) prevents the growth of Neisseria meningitides, but promotes the growth of Neisseria gonorrhoeae.

Q: The component that enriches chocolate agar is A) chocolate. B) methyl brown indicator dye. C) heat-lysed blood cells. D) None of the answers are correct.

Q: An Etest is a clinical tool used for the determination of A) enteric presence. B) Escherichia coli O157:H7 presence. C) the minimum inhibitory concentration (MIC) value of an antimicrobial agent. D) pathogenic enzyme activity.

Q: MacConkey agar and eosin-methylene blue (EMB) agar are ________ media. A) selective but not differential B) differential but not selective C) both selective and differential D) neither selective nor differential

Q: The most common of all nosocomial infections are ________ infections. A) blood B) reproductive tract C) urinary tract D) respiratory tract

Q: Which of the following must be accomplished FIRST in order to conduct RT-PCR? A) Complementary DNA must be synthesized from double-stranded DNA. B) Complementary DNA must be synthesized from RNA. C) Complementary DNA must be synthesized from proteins. D) Complementary DNA must be synthesized from single-stranded DNA.

Q: Bacteremia is a term used A) to indicate the presence of bacteria in the blood. B) synonymously with septicemia. C) when the same organism is isolated from more than one site. D) to indicate the presence of bacteria in the lungs.

Q: Laboratories that work with moderate risk pathogens are classified as A) BSL-1. B) BSL-2. C) BSL-3. D) BSL-4.

Q: Given that T cell receptors (TCRs) are randomly generated during the maturation process, how are new T cells selected that can recognize self-antigens and other immune cells appropriately?

Q: Why is the secondary immune response stronger in regard to antibodies?

Q: Design five amino acid peptides that could be bound by a single hypothetical class I MHC protein. The MHC proteins binds peptides that are 10 amino acids long and have two anchor residues, tyrosine and isoleucine, at positions 2 and 5.

Q: Predict the consequence for an individual of a deleterious genetic mutation in the gene for TLR-4.

Q: Major histocompatibility complex (MHC) proteins, antibodies, and T cell receptors are all highly variable so that they can interact with a large number of different antigens. How is variability generated for each of these important antigen-binding proteins?

Q: A patient is waiting for a kidney transplant. In order for the transplant to be successful, the donated kidney (the graft) must "match" with the recipient. What has to "match" between the donor and the recipient? Why is matching tissue more difficult than matching blood types?

Q: What is the effect of an antigen binding a membrane protein on adapter molecules?

Q: What role does the C domain play in cell surface proteins that interact directly with antigens?

Q: Describe the signal transduction pathway that is activated when LPS binds to TLR-4.

Q: After a B cell is activated, it no longer needs T cell interactions or cytokines to make antibody.

Q: Some immature B cells are reactive to self-antigens but do not become activated even when exposed to high concentrations of self-antigens.

Q: T cells undergo immune selection FOR potential antigen-reactive cells and selection AGAINST those cells that react strongly with self-antigens.

Q: Selection against self-reactive clones results in the development of tolerance.

Q: In clonal selection, cells that have not interacted with antigen do not proliferate.

Q: The clonal selection theory states that each antigen-reactive B cell or T cell has a cell surface receptor for a single antigen epitope.

Q: Somatic hypermutation mechanisms generate TCR diversity.

Q: In antigen binding, MHC protein binds to the T cell epitope, whereas the TCR binds the MHC motif.

Q: Affinity maturation is one of the factors responsible for a stronger secondary immune response.

Q: In somatic hypermutation, the mutation of immunoglobulin genes occurs at much higher rates than the mutation rates observed in other genes.

Q: Antibodies are insoluble proteins.

Q: Each immunoglobulin or TCR interacts with a single antigen, but MHC proteins can interact with more than one antigen.

Q: Class I MHC proteins have grooves with open ends.

Q: The arrangement of Class II MHC proteins in pairs or trimers enhances their stability.

Q: The embedded peptides in MHC proteins are normally derived from breakdown products of cell metabolism.

Q: The human leukocyte antigen spans about 4Mbp on human chromosome 6.

Q: Adapter molecules associate covalently with their respective antigen receptors in the membrane.

Q: Immunoglobins associate with the adapter molecules Igα and Igβ.

Q: The cytoplasmic domains of immunoglobulins and TCRs have cytoplasmic tyrosines that can be phosphorylated.

Q: Antigen receptors can directly connect to signal transduction pathways because immunoglobulins and TCRs have very small cytoplasmic domains.

Q: B cells react with antigens through TCR antigen receptors.

Q: Immunoglobulin, TCR, and MHC proteins share structural features and have evolved by duplication and selection of primordial antigen receptors.

Q: TCRs are found exclusively on T cells.

Q: All TLR can react with only one specific PAMP.

Q: Mannose on mammalian cells is inaccessible to mannose-binding lectin.

Q: When two allelic variants are expressed equally, they are said to be A) exclusive. B) uncommitted. C) repressed. D) codominant.

Q: All proinflammatory cytokines EXCEPT ________ induce fever at the systemic level. A) IL-4 B) IL-12 C) IL-6 D) IL-17

Q: Cytokines produced by lymphocytes are often called A) interleukins. B) pathogen recognition receptors. C) chemokines. D) epitopes.

Q: Some activated B cells are transformed into ________ cells that secrete antibodies, and others remain as ________ cells. A) plasma / memory B B) lymphocytes / memory B C) immunoglobulin / plasma D) immunoglobulin / TH

Q: In B cell selection and tolerance, if no signal is generated from ________ cells, the B cells remain unresponsive. A) TC B) TH C) B7 D) CD28

Q: The failure to develop tolerance may result in dangerous reactions to self-antigens, a condition called A) type I hypersensitivity. B) immunotolerance. C) autoimmunity. D) immunodeficiency.

Q: The mechanism by which antigen-reactive cells respond to foreign antigens while ignoring self-antigens is called clonal A) selection. B) deletion. C) anergy. D) expansion.

Q: ________ ensures that each B cell produces only one immunoglobulin. A) Self-activation B) Allelic exclusion C) MHC interaction D) Clonal deletion

Q: The antigen-binding site of an antibody accommodates a small portion of the antigen called a(n) A) lipopolysaccharide. B) epitope. C) peptide motif. D) pathogen associated molecular pattern (PAMP).

Q: Amino acid variability is especially apparent in several ________ in the V domains of different immunoglobulins. A) heavy chains B) complementarity-determining regions (CDR) C) peptide motifs D) epitopes

Q: The invariant amino acids in each peptide motif bound by MHC proteins are called A) anchor residues. B) MHC peptides. C) antigen-binding immunoglobulins. D) TCR peptides.

Q: The peptides bound by a single MHC protein share a common A) C domain. B) peptide motif. C) V domain. D) nucleotide sequence.

Q: The occurrence of multiple alleles at a specific locus is called A) signal transduction. B) the variable domain. C) polymorphism. D) allelic exclusion.

Q: The ________ and ________ domains of the class II MHC protein interact to form a peptide-binding site.A) B / TB) light / heavyC) C / VD) 1 / 1

Q: The major histocompatibility complex is also called the A) human leukocyte antigen (HLA). B) T cell receptor. C) toll-like receptor complex. D) T cell receptor or toll-like receptor.

Q: Immunoglobulins and TCRs associate with adaptor molecules that have A) a C domain. B) immune-based tyrosine-activation motifs (ITAMs). C) pathogen recognition receptors. D) toll-like receptors.

Q: The ________ is a highly conserved amino acid sequence found in immunoglobulin, TCR, and MHC proteins. A) heavy chain B) V domain C) C domain D) light chain

Q: Signal transduction pathways initiate activation of transcription after specific A) TH cell death. B) ligand-receptor binding on the cell surface. C) cytokines diffuse across the cytoplasmic membrane. D) antigen-antibody binding.

Q: Interaction of a PAMP with a TLR triggers transmembrane signal transduction and subsequent A) clonal expansion. B) antibody production. C) complement protein activation. D) phagocytosis and inflammation.

Q: Which of the following is a likely target for a toll-like receptor (TLR)? A) tumor necrosis factor B) interleukin IV C) flagellin D) insulin

Q: The PAMP recognized by mannose-binding lectin (MBL) is the sugar mannose, found as a repeating subunit in A) human mucus. B) lymphocyte receptors. C) bacterial and fungal polysaccharides. D) bacterial peptidoglycan.

Q: The chemokine CCL2 A) attracts basophils, eosinophils, monocytes, and dendritic cells. B) stimulates production of inflammatory mediators. C) organizes an antigen specific immune response. D) attracts basophils, eosinophils, monocytes, and dendritic cells; stimulates production of inflammatory mediators; and organizes an antigen specific immune response.

Q: Chemokines produced by activated macrophages include A) CXL8. B) CCL2. C) MCP-1. D) CXL8, CCL2, and MCP-1.