Micro Final Answers – Flashcards

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Antigen processing and presentation
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is a way for a cell to give information about its activities.
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Why would a body cell that is not a phagocyte need to present antigens?
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Non-phagocytic body cells can become infected with a virus.
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How do phagocytes communicate to other cells what they have captured?
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They present antigens from engulfed foreign cells.
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Which structure do antigen presenting cells utilize to directly help them present bacterial antigens?
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Phagolysosome
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Which of the following are likely to be found on an MHC-I protein?
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Damaged mitochondrial fragment
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What would a virally infected skin epithelial cell have on its cell surface?
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Class I MHC with skin cell antigens
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Which of the following would you likely see on the surface of a human dendritic cell following phagocytosis of a bacterium?
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Class I MHC with dendritic cell antigens and Class II MHC with engulfed bacteria
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Tom has a genetic disorder in which he does not synthesize class I MHC proteins or functional NK cells. Which of the following statements would be true for Tom?
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Tom would not be able to destroy virally-infected cells.
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Which of the following statements concerning antigen-presenting cells is true?
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They are involved in activating T cells.
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Which part of the adaptive immune response involves B cells?
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Humoral
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Antibodies are a part of which type of immunity?
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Humoral
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Phagocytosis is a process for engulfing large particles (>1?m). Which feature of antibodies will help to make particles larger, therefore enhancing phagocytosis?
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agglutination
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The flu virus mutates fairly frequently. Its adhesive proteins change such that we have different "strains" of influenza each year. When a particular flu virus mutates such that its adhesive proteins change, which function of antibodies is disrupted?
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neutralization
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__________________ stimulated with ___________ differentiate into __________, which secrete antibodies into the bloodstream.
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B-cells, antigen, plasma cells
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What is the correct sequence of events for activation of a B cell by a T-dependent antigen?
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(1) Immunoglobulin receptors on the B cell recognize and bind the antigen. (2) An antigen fragment in complex with MHC class 2 is displayed on the B cell's surface. (3) The MHC-antigen complex binds a receptor on a TH cell. (4) The TH cell secretes cytokines that activate the B cell.
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If a patient has been exposed to an antigen for the first time, which class of immunoglobulin appears first?
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IgM
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Which type of cell directly attacks infected cells?
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Immune cells that secrete cytokines and activate other immune cells are:
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HIV directly infects T-cells. Why is this problematic for cell-mediated immunity?
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Cytotoxic T-cells begin to attack the virally infected T-cells, reducing the number of T-cells in the body.
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How do helper T-cells and cytotoxic T-cells work together?
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Helper T-cells produce cytokines to activate other cells of the immune system.
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Which of the following statements concerning cellular immunity is FALSE?
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Cellular immunity involves cells that recognize antigens and make specific antibodies against them.
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Which type of T cell is involved in activating macrophages and stimulating development of cytotoxic T cells?
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TH1 cells
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innate immunity
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includes cilia, mucous membranes, and dendritic
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humoral immunity
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immunological response brought about by antibody production
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cellular immunity
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immunological response that kills infected host cells
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immature B cells
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use BCRs to recognize epitope; first step in clonal selection
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dendritic cells
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phagocytes that engulf anything foreign; eventually display epitope to helper T cells using MHC I or II
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Th cells
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lymphocytes that activate B cells and CTLs
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memory cells
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differentiated B cells that are stored in lymph nodes to provide protection against future infection by the same pathogen
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plasma cells
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produce and secrete antibodies
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Tc cells
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kill infected host cells
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An individual may be exposed to a pathogen and become infected without actually getting sick. This is known as a subclinical infection. Even in subclinical infections, the individual's adaptive immune system can generate memory for the pathogen. What type of adaptive immunity is this?
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naturally acquired active immunity
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Which cytokines are believed to contribute to autoimmune disease, such as rheumatoid arthritis?
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tumor necrosis factor (TNF)

The tumor necrosis factor (TNF) family of cytokines are the ones that help to protect against tumors but also play a role in some autoimmune diseases.

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Consider a helminthic infection in which an individual is colonized by a parasitic worm. The worm is too big to be engulfed by a phagocytic cell. How does the immune system respond?
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The worm gets coated with antibodies, which activate other cells in the immune system to secrete chemicals that kill it.
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Which of the following statements concerning immunological memory is true?
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The memory response is due to production of long-lived cells that can respond very rapidly upon second exposure.
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What does a vaccine contain?
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Weakened or killed pathogen or parts of a pathogen
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When a person has previously been vaccinated against a viral pathogen, which cells are activated if that same pathogen re-enters the host's cells months or years later?
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Memory cytotoxic T cells
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What is the primary benefit of vaccination?
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An immune response will occur quicker upon future exposure to the pathogen.
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Which type of vaccine could possibly cause a person to develop the disease?
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Attenuated live vaccine
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What is the hallmark of a conjugated vaccine?
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These vaccines contain weakly antigenic elements plus a more potent antigenic protein.
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The influenza vaccine is an example of a(n)
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inactivated killed vaccine.
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What is the function of boosters?
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Boosters are injections that are given periodically to maintain immunity.
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The Hepatitis B vaccine is which type of vaccine?
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BCG is a vaccine against Mycobacterium tuberculosis. The vaccine is composed of a live Mycobacterium bovis variant called bacillus of Calmette and Guerin. This is an example of which type of vaccine?
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attenuated whole agent vaccine
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To vaccinate children against the bacterial infection diphtheria, pure diphtheria toxin is chemically modified and injected as a vaccine. This is an example of which type of vaccine?
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toxoid vaccine
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Patients can receive one of two different types of influenza vaccine, both of which use whole viruses. The nasal spray uses live virus and is an example of a(n) ________ vaccine, while the injection uses killed virus and is an example of a(n)___________ vaccine.
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attenuated whole agent, inactivated whole agent
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Which of the following best describes vaccination?
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An individual is exposed to a killed pathogen, an inactivated pathogen, or a component of a pathogen. The individual is protected from subsequent exposures to the pathogen because the adaptive immune system is stimulated to produce memory B cells and memory T cells, which protect from subsequent exposures.
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Which of the following is NOT an advantage of using live attenuated vaccines?
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They are usually safer than other types of vaccines.
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What is an adjuvant?
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a chemical additive that increases the effectiveness of vaccines
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I have a new test for determining whether a patient is infected with the influenza virus. It is very specific but not very sensitive. What does this mean?
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False-positives will be rare, but false-negatives may happen frequently.
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You are conducting a viral hemagglutination inhibition test. Which of the following indicates that a patient's serum has antibodies against influenza virus?
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Hemagglutination occurs in a mixture of influenza virus and erythrocytes but does not occur when the patient's serum is added.
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They are always highly sensitive.
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__________ reactions are used to detect antibodies for relatively large pathogens, such as bacteria. For these tests, the antigen is mixed with the test sample at various dilutions. Reaction mixes are then monitored for the formation of visible aggregates.
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Agglutination
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Direct fluorescent-antibody techniques are frequently used to __________.
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detect microorganisms in a clinical sample
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What is the purpose of conjugated vaccines?
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to enhance the immune response of children to polysaccharide antigens
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Western blotting is best used for which of the following?
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to detect a specific protein in a mixture
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Which of the following does histamine NOT directly cause?
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Which of the following would NOT be an example of a common allergen?
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hay fever
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A patient enters the emergency room with itchy, swollen hives. This is an example of a ___________ allergic response called __________.
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localized; urticaria
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Which of the following is FALSE concerning type II (cytotoxic) hypersensitivity reactions?
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IgE binds to mast cells or basophils.
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Assuming Rh compatibility is present, which of the following individuals would be able to receive donor blood from any of the four blood types (A, B, AB, and O)?
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AB
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Which type of hypersensitivity is allergic contact dermatitis?
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type IV reaction
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Which of the following is a characteristic of rheumatoid arthritis?
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Immune complexes of IgM, IgG, and complement are involved.
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Which of the following is true concerning systemic anaphylaxis?
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Injected antigens combine with IgE antibodies on the surface of certain cells, causing them to release histamines and other inflammatory mediators.
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Which of the following best describes graft-versus-host disease?
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Immune cells in transplanted bone marrow attack the cells of the host.
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Which statement regarding cancer immunotherapy is FALSE?
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An immunotoxin is an antigen combined with a toxic agent.
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Which of the following correctly lists the current distribution of HIV infection and AIDS in order of DECREASING prevalence?
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sub-Saharan Africa, Latin America, Western Europe, Australia / New Zealand
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Which statement regarding the infectiveness and pathogenicity of HIV is FALSE?
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During latent infections, the provirus directs the synthesis of many new viruses.
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Which of the following is a xenograft?
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the replacement of a human's heart valve with a pig's heart valve
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What is meant by selective toxicity?
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Chemotherapeutic agents should act against the pathogen and not the host.
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Why are chemotherapeutic agents that work on the peptidoglycan cell wall of bacteria a good choice of drug?
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Humans and other animal hosts lack peptidoglycan cell walls.
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Why is polymyxin only used on the skin?
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It can also damage living human cell membranes, but the drug is safely used on the skin, where the outer layers of cells are dead.
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Quinolones and fluoroquinolones act against what bacterial target?
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DNA gyrase
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Why is it difficult to find good chemotherapeutic agents against viruses?
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Viruses depend on the host cell's machinery, so it is hard to find a viral target that would leave the host cell unaffected.
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If penicillin G is chosen as the best treatment for a given infection, what microorganisms are most likely the cause?
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gram-positive bacteria
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How do antifungal drugs such as miconazole and amphotericin B function?
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by disrupting the plasma membrane
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Which of the following is an antiprotozoan drug that interferes with anaerobic metabolism?
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metronidazole
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Why is methicillin-resistant Staphylococcus aureus (MRSA) methicillin resistant?
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It produces a modified version of the molecule that is targeted by the drug.
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Sulfanilamides interfere with __________.
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folic acid synthesis in bacteria
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Certain cancer cells have ABC transport molecules at the cell surface. These transporters use energy from ATP to move chemotherapeutic agents out of the cell. Which of the following do you think these transporters are most closely related to?
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membrane pumps
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A researcher creates an antibiotic that binds to a protein present only on B. anthracis (the causative agent of anthrax), lysing the cell from the outside. After a couple of years using this antibiotic, some resistant organisms are found. Which of the following best outlines the mechanism for development of this resistance?
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mutation in B. anthracis > altered target > resistant bacterium
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A new bacterial molecule is discovered. This molecule binds to an antibiotic and facilitates the binding of a phosphate group, thus inactivating the antibiotic. Which category best describes the mechanism of antibiotic resistance conferred by this molecule?
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bacterial enzymes
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Which antibiotic is overcome by beta-lactamases?
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Penicillin
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How might efflux pumps increase antibiotic resistance in bacteria?
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Resistant bacteria can have more efflux pumps, and can have less specific efflux pumps.
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Bacteria that are resistant to sulfonamide have enzymes that have a greater affinity for what?
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PABA
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Why would an efflux pump for penicillin located on a bacterial cell membrane not be effective at providing resistance to the drug?
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Penicillin disrupts the cell wall, which is located outside of the cell membrane.
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Membrane transport proteins are required for which mode(s) of antibiotic resistance?
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Efflux pumps, beta-lactamases, and modification of porins all utilize membrane transport proteins.
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What is meant when a bacterium is said to become "resistant" to an antibiotic?
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The bacterium is neither killed nor inhibited by the antibiotic.
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When a patient is treated with antibiotics, __________.
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the drug will kill or inhibit the growth of all of the sensitive bacterial cells
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The process of acquiring antibiotic resistance by means of bacteriophage activity is called
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transduction
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Which of the following mutations would not result in antibiotic resistance?
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Silent mutation
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R-plasmids are most likely acquired via
Check all that apply.
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bacterial conjugation.
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Consider a Kirby-Bauer disk-diffusion assay. If you put penicillin and streptomycin disks adjacent to one another, the zone of inhibition is greater than that obtained by either disk alone. This is an example of __________.
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synergism
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What type of cell wall has teichoic acid?
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gram-positive
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What type of cell wall has a thick layer of peptidoglycan on the outside?
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gram-positive (gram-negative have thinner layer that is b/w the outer and inner membranes)
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What type of cell wall has lipopolysaccharides, which are responsible for symptoms related to infection?
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gram-negative
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