Chapter 5 Microbiology – Flashcards
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Viruses are best viewed by
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electron microscopy
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The central core of a virus particle consists of
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nucleic acid
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The simplest virus is a
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naked virus
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A viral capsid is composed of
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proteins
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The genetic material found in a virion is usually
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Either DNA or RNA
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Which of the following is not an acellular agent?
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Rickettsia
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Enveloped viruses include
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herpes virus
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The main criteria presently used for grouping viruses does not include
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host infected
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The term Poxviridae indicates that we are looking at a virus
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family
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In general RNA viruses multiply in the cell ______ and DNA viruses multiply in the cell ______
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Cytoplasm; nucleus
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Viruses cannot be cultivated in
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blood agar
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Identify the proper order of phases in the life cycle of animal viruses:
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adsorption, penetration, uncoating, synthesis, assembly, and release
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Viral spikes or peptomers are involved in
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attachment
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Lysogeny refers to
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viral genome inserting into bacterial host chromosomes
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Which of the following will not support viral cultivation
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Live lab animals, embryonated bird eggs, primary cell cultures, continuous cell cultures; all of the above
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Living cells are required for culturing viruses because
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viruses are technically nonliving, viruses require host cell genetic machinery to replicate, viruses are obligate intracellular parasites; all of the above
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The classification/identification system in the text uses the sequence of characteristics to group viruses:
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Nucleic acid type, envelope presence/absence, double vs single-stranded nucleic acid
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One way to detect the growth of a virus in culture is to observe the degeneration and lysis of infected cells in the monolayer of cells. These areas show up as clear, well-defined patches in the cell sheet called
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plaques
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Viruses can cause damage to infected cells, such as physical damage, nuclear inclusions, cytoplasmic inclusions, clumping, etc. These are termed
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cytopathic effects
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Which of the following viruses is NOT definitely linked to causing cancer in humans?
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Rabies virus
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Which of the following statements is untrue
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Viruses multiply inside living cells using viral mRNA, tRNA, and viral ribosomes
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Spongiform encephalopathies are thought to be caused by
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prions
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A common virion release method observed in enveloped viruses is
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budding
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true or false: Each viral envelope is constructed from identical subunits called capsomeres.
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false
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true or false: in penetration by endocytosis, the entire virus is engulfed by the cell enclosed in a vacuole or vesicle.
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true
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a virus specific for a bacterial host is called a
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phage
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true or false: an envelope is present in all viruses
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false
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true or false: Many RNA viruses have segmented genomes with each segment coding for a protein.
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true
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true or false: All viruses inject their nucleic acid into the cytoplasm of their host, leaving the capsid outside and attached to the cell wall
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false
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true or false: human immunodeficiency virus (HIV) enters the host cell by fusing directly with the host cell plasma membrane.
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true
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true or false: when viral cells are released via budding, the host cell may survive and continue releasing virions for some time.
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true
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true or false: viruses are easily cultivated in agars and broths, much like bacteria
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false
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Host range is limited by
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type of host cell receptors on cell membrane
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A negative-sense RNA virus
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must synthesis a positive RNA copy of its genome
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Viruses have all the following except
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metabolism
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oncoviruses include all the following except
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measles virus
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visible, clear, well-defined patches in a monolayer of virus-infected cells in a culture are called
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plaques
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the development of antiviral drug therapy is difficult because
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viruses are obligated intracellular parasites so the host cell can be harmed by the drug
