microbiology chapter 13 – Flashcards
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We sometimes are able to generate antibodies (immune system proteins) that bind to and cover up some of the proteins on the outermost portion of a virus while it is in the bloodstream. This renders the virus unable to reproduce. Which step of viral replication are antibodies directly preventing? synthesis uncoating assembly attachment
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attachment
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Enveloped viruses have a layer of lipids surrounding their capsid. This envelope is made mostly of host cell membrane. In which step does the virus acquire this envelope? release attachment synthesis assembly
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release
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What occurs during viral uncoating? The nucleic acid breaks apart, allowing for translation. The capsid breaks apart, releasing the viral genome. The viral envelope is released. The viral proteins are synthesized.
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The capsid breaks apart, releasing the viral genome.
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The normal function of the PrP protein in mammals is believed to be: assisting in normal membrane development and function. assisting proteins in forming beta-pleated sheets. assisting in normal synaptic development and function. assisting proteins in forming alpha-helices.
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assisting in normal synaptic development and function.
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How do normal prion proteins (PrP) differ from the infectious prion proteins? Normal PrP are found in all mammals; infectious PrP are found in only cows. Normal PrP lack nucleic acid; infectious PrP have nucleic acid. Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets. Normal PrP are found on mammals; infectious PrP are found on reptiles.
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Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
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How does the number of infectious prions increase? Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion. Prions form multimers which can then form more single copies of the prion protein. Prions reproduce by binary fission. Prions reproduce by mitosis.
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Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
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Why are the beta-pleated multimers of PrP potentially pathogenic? They are found on the surface of immune cells, resulting in damage to the immune system. They are not detected by other organisms. The multimers are more stable and resistant to protease. They repress the immune system.
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The multimers are more stable and resistant to protease.
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A viroid is a(n) complete, infectious virus particle. provirus. infectious protein. infectious piece of RNA without a capsid. capsid without nucleic acid.
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infectious piece of RNA without a capsid.
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Which of the following statements about viral spikes is FALSE? They are used for attachment. They may cause hemagglutination. They bind to receptors on the host cell surface. They are composed of carbohydrate-protein complexes. They are found only on nonenveloped viruses.
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They are found only on nonenveloped viruses.
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Viruses that utilize reverse transcriptase belong to the virus families Herpesviridae and Poxviridae. Herpesviridae and Retroviridae. Rhabdoviridae and Herpesviridae. Retroviridae and Picornaviridae. Hepadnaviridae and Retroviridae.
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Hepadnaviridae and Retroviridae.
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A clear area against a confluent "lawn" of bacteria is called a pock. rash. phage. plaque. cell lysis.
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plaque.
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Oncogenic viruses are genetically unstable. cause acute infections. cause tumors to develop. have no effect on the host cell. are lytic viruses that kill the host cell.
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cause tumors to develop.
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An example of a latent viral infection is mumps. smallpox. influenza. cold sores. subacute sclerosing panencephalitis.
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cold sores.
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A virus's ability to infect an animal cell depends primarily upon the host cell's ability to phagocytize viral particles. type of viral nucleic acid. enzymatic activity of a host cell. presence of receptor sites on the cell membrane. presence of pili on the host cell wall.
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presence of receptor sites on the cell membrane.
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________ were first identified in cancer-causing viruses and can induce ________ in infected cells. T antigens; lysis Glycoprotein spikes; syncytia formation Segmented genomes; reassortment Oncogenes; transformation Herpes viruses; lesions
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Oncogenes; transformation
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Assume a patient has influenza. During which time on the graph in the figure would the patient show the symptoms of the illness? a b c d e
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c
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How do all viruses differ from bacteria? Viruses are obligate intracellular parasites. Viruses are not composed of cells. Viruses do not have any nucleic acid. Viruses are filterable. Viruses do not reproduce.
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Viruses are not composed of cells.
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Which of the following statements provides the most significant support for the idea that viruses are nonliving chemicals? They cannot reproduce themselves outside a host. They are chemically simple. They cause diseases similar to those caused by chemicals. They are not composed of cells. They are filterable.
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They cannot reproduce themselves outside a host.
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TRUE/FALSE: Dogs do not get measles because their cells lack the correct receptor sites for that virus.
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true
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In the figure, which structure is a complex virus? a b c d All of the structures are complex viruses.
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b
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TRUE/FALSE: Helical and icosahedral are terms used to describe the shapes of a virus envelope.
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false
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Continuous cell lines differ from primary cell lines in that continuous cell lines can be maintained through an indefinite number of generations. continuous cell lines are from human embryos. continuous cell lines always have to be re-isolated from animal tissues. viruses can be grown in continuous cell lines. continuous cell lines are derived from primary cell lines.
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continuous cell lines can be maintained through an indefinite number of generations.
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The definition of lysogeny is the period during replication when virions are not present. attachment of a phage to a cell. when the burst time takes an unusually long time. phage DNA is incorporated into host cell DNA. lysis of the host cell due to a phage.
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phage DNA is incorporated into host cell DNA.
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An envelope is acquired during which of the following steps? uncoating release penetration adsorption biosynthesis
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release
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The mechanism whereby an enveloped virus leaves a host cell is called penetration. abduction. budding. transduction. lysogeny.
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budding.
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Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves lysis of the host cell. assembly of viral components. adsorption to specific receptors. replication of viral nucleic acid. injection of naked nucleic acid into the host cell.
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injection of naked nucleic acid into the host cell.
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A persistent infection is one in which the disease process occurs gradually over a long period. host cells are gradually lysed. the virus remains in equilibrium with the host without causing a disease. host cells are transformed. viral replication is unusually slow.
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the disease process occurs gradually over a long period.
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An enveloped animal virus penetrates its host cell by: fusing its envelope with the plasma membrane endocytosis budding lysis using lysozyme to digest the cell wall
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fusing its envelope with the plasma membrane
