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Combo with Chapter 13 Mastering Micro HW and 2 others

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In what year did Stanley Prusiner discover prions?
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1982
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Which disease did Stanley Prusiner first identify as being caused by prions?
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scrapie
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How are prions different from other infectious agents?
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they lack nucleic acid
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Lysogenic viral DNA integrating into the host genome is referred to as
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prophage
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Which of the following events might trigger induction of a temperate bacteriophage? ANSWER: 1) Normal cell division of an infected cell 2) Bacterial conjugation 3) An infected cell entering the logarithmic phase of growth 4) Exposure to UV light
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Exposure to UV light
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How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
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The host cell dies during the lytic stage.
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What is the fate of the prophage during the lysogenic stage? 1) It is packaged into viral proteins and maintained until the host is exposed to an environmental stress. 2) It is copied every time the host DNA replicates. 3) It is degraded by the activity of host defense enzymes. 4) It is released from the cell by lysing the cell.
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It is copied every time the host DNA replicates.
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How do naked viruses differ from enveloped viruses in their attachment/penetration phase?
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Their nucleic acids are injected into the cell.
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Which virus employs the use of an RNA-dependent RNA polymerase?
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+RNA viruses
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Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
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retroviruses
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Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane? +RNA viruses dsRNA viruses Naked viruses Enveloped viruses
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enveloped viruses
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Which of the following can be used directly as messenger RNA? +RNA -RNA ssDNA
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+RNA
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Which of the following statements concerning prion diseases is true? Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc). Prion diseases are always inherited. Prion diseases affect humans but not other animals. Prion diseases affect brain function but do not affect the morphology (overall appearance) of brain tissues.
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Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).
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Which of the following statements concerning viruses is true? Viruses contain both DNA and RNA, and they undergo binary fusion. Viruses possess enzymes for protein synthesis and ATP generation. The “host range” for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach. Viruses are usually about the same size as bacteria.
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The “host range” for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.
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In which stage is the viral DNA introduced into the cell?
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penetration
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In which stage does formation of mature viruses occur?
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assembly/maturation
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The host DNA is usually degraded during which stage?
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biosynthesis
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What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage? The virus would infect new hosts. The virus would not be able to infect new hosts. The cell could still be revived by the virus.
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The virus would not be able to infect new hosts.
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Name the human disease caused by prions?
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Creutzfeldt-Jakob disease (CJD)
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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?
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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?
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release
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What occurs during viral uncoating?
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The capsid breaks apart, releasing the viral genome.
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Which of the following statements regarding latent viral infections is true? During latent infections, small amounts of virus are produced, and virus numbers build up over time. Latent infections can persist for years in an individual without causing any symptoms. Latent viral infections are caused by the slow conversion of cellular glycoproteins from normal to infectious form. Latent viral infections are almost always fatal.
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Latent infections can persist for years in an individual without causing any symptoms.
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Which statement is CORRECT concerning animal viruses? The genome of animal viruses is always single-stranded. Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA. Capsid proteins are produced in the nucleus. Enveloped viruses are surrounded by a lipid and carbohydrate coat, which is made from the host cell’s mitochondria.
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Retroviruses use an enzyme called reverse transcriptase, which synthesizes DNA by copying RNA.
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Which of the following is true concerning a lysogenic viral replication cycle? ANSWER: Lysogenic infections are similar to persistent infections, in that virus is constantly produced. During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome. During lysogeny, the viral DNA is present as a circular plasmid. Once the lysogenic portion of the cycle has begun, virus is never produced again.
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During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
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Which virus is NOT associated with cancer? ANSWER: Epstein-Barr virus (EBV) coronavirus human papillomavirus (HPV) hepatitis B virus (HBV)
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coronavirus
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The normal function of the PrP protein in mammals is believed to be:
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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?
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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?
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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 pathog
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The multimers are more stable and resistant to protease.
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protection and recognition
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The outermost layer of a virion fulfills what functions of the virus?
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nucleic acid
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During the intracellular state, a virus exists as
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type of nucleic acid
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Viruses are primarily classified according to their
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interactions
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Host specificity of a virus is due to
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envelope
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What would NOT be found as a component of a bacteriophage?
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in both cells and viruses
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A lipid membrane is present
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both cells and viruses
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Double-stranded DNA genomes are found in
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cells only
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Cytoplasm is a characteristic of
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true
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Most viruses cannot be seen by light microscopy. TRUE OR FALSE
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true
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Protozoa are susceptible to viral attack. TRUE OR FALSE
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they require a host to reproduce
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How are viruses different from cells?
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package and protect the viral genome
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What is the function of the structural elements of a virus?
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a prophage
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Lysogenic viral DNA integrating into the host genome is referred to as
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exposure to UV light
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what event might trigger induction of a temperate bacteriophage?
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host cell dies during lytic stage
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How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
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copied every time the host DNA replicates
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What is the fate of the prophage during the lysogenic stage?
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penetration
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In which stage is the viral DNA introduced into the cell?
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assembly
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In which stage does formation of mature viruses occur?
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biosynthesis
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The host DNA is usually degraded during which stage?
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virus would not infect the new host
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What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
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lysogenic conversion
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Bacteriophage genes that cause toxin production in a normally harmless bacterial species are an example of _____.
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the infected cell may live for a long time
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Infections with enveloped animal viruses are similar to lysogenic phage infections because _____.
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entry and release
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Lysozyme is important for which of the following stages of lytic replication in bacteriophage T4?
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UV light and X rays
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What agent is capable of inducing conversion of a prophage back to a lytic phage?
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prusiner
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Which of the following individuals discovered prions?
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virion
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what is a virus in the extracellular state?
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plant
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The first virus to be identified was isolated from a _____.
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protein
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The capsid of a virus is made out of which of the following types of molecules?
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prion
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does NOT refer to viral shapes
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dependent on host cell
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Why do viruses have to infect host cells?
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attachment
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The tail fibers of a bacteriophage are most useful during which of the following stages of the lytic replication cycle?
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viral DNA
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Which of the following is a major difference between a lysogenic and a lytic cycle in bacteriophages?
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retroviruses
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What viruse creates a DNA intermediary molecule from the information in their RNA genomes?
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herpesviruses
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What types of viruse replicates in the cell’s nucleus?
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rna dependent
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What type of viruses replicates in the cell’s nucleus?
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cytoplasmic membrane
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Bacteriophages can use all of the following structures for attachment to a bacterial cell EXCEPT _____.
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envelope
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A naked virus is one without _____.
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uncoating
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Each of the following features is common to BOTH bacteriophage AND animal virus infections EXCEPT __________.
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phage persists
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Each of the following features is common to BOTH bacteriophage AND animal virus infections EXCEPT __________.
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cancer causing viruses
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In the early 1900s, the virologist F. Peyton Rous discovered _____.
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allow bacteriophages to become latent
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Fertilized chicken eggs are useful for the culture of viruses for all of the following reasons EXCEPT _____.
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continuous
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HeLa cells are an example of a __________ cell culture.
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contain no nucleic acid
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Scientists have determined that prion diseases are not caused by a type of slow virus because prions _____.
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true
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Viruses have genomes of DNA or RNA, but never both. TRUE OR FALSE
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true
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Viruses can specifically infect one type of cell within an organism. TRUE OR FALSE
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true
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Bacteriophages outnumber all known life forms. TRUE OR FALSE
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false
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According to the ICTV scheme of classification, viruses can be classified by a variety of characteristics, including the diseases they cause. TRUE OR FALSE
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true
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Proviruses become a permanent part of the host cell’s genome. TRUE OR FALSE
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true
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Bacteriophages can be used in place of antibiotics to treat certain bacterial diseases. TRUE OR FALSE
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true
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Lysogenic bacteriophages can be excised from the chromosome by any agent that damages the cell’s DNA. TRUE OR FALSE
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false
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Retroviruses need RNA-dependent RNA transcriptase to replicate themselves. TRUE OR FALSE
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false
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Diploid cell cultures have an unlimited life span. TRUE OR FALSE
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false
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The destruction of chickens and other domesticated fowl prevents the spread of avian influenza. TRUE OR FALSE
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false
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An infection in which a host cell sheds new viruses slowly and steadily is called a latent infection. TRUE OR FALSE
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spongiform encephalopathies
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As a group, prion diseases are more formally known as _____.
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true
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An icosahedral capsid is the most common type of polyhedral capsid and is also found in bacteriophage. TRUE OR FALSE
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viroids
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Small, circular RNA molecules that are infectious to plants are called _____.
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false
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Viruses are classified into kingdoms and divisions, just like bacteria and eukaryotes.
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induction
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A prophage is excised from the host chromosome and viral replication proceeds in a process called _____.
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false
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The viral envelope contains phospholipids and proteins, all of which originate from the host membrane.
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assembly
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Which step in the viral life cycle is usually a spontaneous process, but is sometimes controlled by viral enzymes?
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false
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If neoplasia occurs, this means that cancer will follow. TRUE OR FALSE
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host membrane merges
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What is the main difference between membrane fusion and endocytosis?
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Which of the following statements concerning viruses is true?
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The “host range” for a virus is determined by the presence or absence of particular components on the surface of a host cell that are required for the virus to attach.
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Which statement concerning viral structure is true?
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Spikes are found on some viruses. They are very consistent in structure and can be used for identification.
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How does specialized transduction differ from regular lysogeny?
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The prophage in specialized transduction carries with it pieces of the host chromosomal DNA.
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What happens to the packaged DNA of a specialized transduced phage when it infects a new recipient cell?
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The host DNA integrates, with the prophage, into the new recipient chromosome.
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How can specialized transduction contribute to the transfer of antibiotic resistance genes in a bacterial population?
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The prophage takes an antibiotic resistance gene with it and is packaged with the newly synthesized viral DNA.
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Which of the following is true concerning a lysogenic viral replication cycle?
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During lysogeny, the viral genome integrates into the host DNA, becoming a physical part of the chromosome.
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How are viruses different from cells?
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They require a host in order to reproduce.
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What is the function of the structural elements of a virus?
answer

To package and protect the viral genome
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How do naked viruses differ from enveloped viruses in their attachment/penetration phase?
answer

Their nucleic acids are injected into the cell.
question

Which virus employs the use of an RNA-dependent RNA polymerase?
answer

+RNA viruses
question

Which of the following viruses is transcribed from RNA to DNA to RNA during the replication cycle?
answer

Retroviruses
question

Which type of virus would produce viral glycoproteins to be expressed on the host cell membrane?
answer

Enveloped viruses
question

Which of the following can be used directly as messenger RNA?
answer

+RNA
question

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?
answer

attachment
question

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?
answer

release
question

What occurs during viral uncoating?
answer

The capsid breaks apart, releasing the viral genome.
question

Which of the following statements regarding latent viral infections is true?
answer

Latent infections can persist for years in an individual without causing any symptoms.
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Which of the following is true regarding cultivation and isolation of animal viruses?
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Diploid cell culture lines, developed from human embryos, are widely used for culturing viruses that require a human host.
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From which phrase is the term “prions” derived?
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Proteinaceous infectious particles
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In what year did Stanley Prusiner discover prions?
answer

1982
question

Which disease did Stanley Prusiner first identify as being caused by prions?
answer

Scrapie
question

How are prions different from other infectious agents?
answer

They lack nucleic acid.
question

The normal function of the PrP protein in mammals is believed to be:
answer

assisting in normal synaptic development and function.
question

How do normal prion proteins (PrP) differ from the infectious prion proteins?
answer

Normal PrP have alpha-helices; infectious PrP have beta-pleated sheets.
question

How does the number of infectious prions increase?
answer

Prions transform normal proteins into the misfolded beta-pleated sheet configuration; therefore, prions multiply by conversion.
question

Why are the beta-pleated multimers of PrP potentially pathogenic?
answer

The multimers are more stable and resistant to protease.
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Which of the following statements concerning prion diseases is true?
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Normal host cellular prion proteins (PrPC) are converted into scrapie proteins (PrPSc).
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Which of the following is true of viroids?
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Viroids are short pieces of naked RNA.
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How do all viruses differ from bacteria?
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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?
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They cannot reproduce themselves outside a host.
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Which of the following statements about viruses is FALSE?
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Viruses use their own catabolic enzymes.
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Which of the following statements about viral spikes is FALSE?
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They are found only on nonenveloped viruses.
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Which of the following is NOT used as a criterion to classify viruses?
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biochemical tests
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What contributes to antigenic shift in influenza viruses?
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a segmented genome
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A viral species is a group of viruses that
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has the same genetic information and ecological niche.
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Viruses that utilize reverse transcriptase belong to the virus families
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Hepadnaviridae and Retroviridae.
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DNA made from an RNA template will be incorporated into the virus capsid of
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Hepadnaviridae.
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Which of the following is NOT utilized to culture viruses?
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culture media
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A clear area against a confluent “lawn” of bacteria is called a
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plaque
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Continuous cell lines differ from primary cell lines in that
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continuous cell lines can be maintained through an indefinite number of generations.
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Lysogenic viral DNA integrating into the host genome is referred to as
answer

a prophage.
question

Which of the following events might trigger induction of a temperate bacteriophage?
answer

Exposure to UV light
question

How is the lytic cycle different from the lysogenic cycle with respect to the infected host cell?
answer

The host cell dies during the lytic stage.
question

What is the fate of the prophage during the lysogenic stage?
answer

It is copied every time the host DNA replicates.
question

In which stage is the viral DNA introduced into the cell?
answer

Penetration
question

In which stage does formation of mature viruses occur?
answer

Assembly
question

The host DNA is usually degraded during which stage?
answer

Biosynthesis
question

What would be the fate of a lytic bacteriophage if the host cell died prior to the assembly stage?
answer

The virus would not be able to infect new hosts.
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Bacteriophages and animal viruses do NOT differ significantly in which one of the following steps?
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biosynthesis
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The definition of lysogeny is
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phage DNA is incorporated into host cell DNA.
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Which of the following statements is FALSE?
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The prophage makes the host cell immune to infection by other phages.
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Lysogeny can result in all of the following EXCEPT
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immunity to reinfection by any phage.
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Which of the following would be the first step in biosynthesis of a virus with a – (minus) strand of RNA?
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synthesis of double-stranded RNA from an RNA template
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An envelope is acquired during which of the following steps?
answer

release
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A viruss ability to infect an animal cell depends primarily upon the
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presence of receptor sites on the cell membrane.
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Assume you have isolated an unknown virus. This virus has a single, positive sense strand of RNA, and possesses an envelope. To which group does it most likely belong?
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togavirus
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The mechanism whereby an enveloped virus leaves a host cell is called
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budding
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Bacteriophages derive all of the following from the host cell EXCEPT
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lysozyme
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Bacteriophage replication differs from animal virus replication because only bacteriophage replication involves
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injection of naked nucleic acid into the host cell.
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Generally, in an infection caused by a DNA-containing virus, the host animal cell supplies all of the following EXCEPT
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DNA polymerase.
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Which of the following places these items in the correct order for DNA-virus replication? 1. Maturation 2. DNA synthesis 3. Transcription 4. Translation
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2; 3; 4; 1
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The following steps occur during multiplication of herpesviruses. Which is the third step?
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uncoating
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The following steps occur during multiplication of retroviruses. Which is the fourth step?
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synthesis of double-stranded DNA
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Which one of the following steps does NOT occur during multiplication of a picornavirus?
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synthesis of DNA
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Most RNA viruses carry which of the following enzymes?
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RNA-dependent RNA polymerase
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T/F The basic mechanism of viral multiplication is similar for all viruses.
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True
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The most conclusive evidence that viruses cause cancers is provided by
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cancer following injection of cell-free filtrates.
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Oncogenic viruses
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cause tumors to develop.
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An example of a latent viral infection is
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cold sores.
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A lytic virus has infected a patient. Which of the following would best describe what is happening inside the patient?
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The virus is causing the death of the infected cells in the patient.
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Some viruses, such as human herpesvirus 1, infect a cell without causing symptoms. These are called
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latent viruses.
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Assume a patient had chickenpox (human herpesvirus 3) as a child. Which line on the graph in the figure would show the number of viruses present in this person as a 60-year-old with shingles (human herpesvirus 3)?
answer

e
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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?
answer

c
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A persistent infection is one in which
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the disease process occurs gradually over a long period.
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Which of the following prion diseases is found in deer and elk?
answer

Chronic wasting disease
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Which of the following prion diseases was also known as laughing disease?
answer

Kuru
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Which of the following conditions in humans is linked to bovine spongiform encephalopathy?
answer

Variant Creutzfeldt-Jakob disease
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What part of the nervous system is most affected by fatal familial insomnia?
answer

Thalamus
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Where does the name “scrapie” come from?
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The prion disorder causes infected sheep to scrape against objects until their skin is raw.
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Which of the following is necessary for replication of a prion?
answer

PrPSc
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An infectious protein is a
answer

prion
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A viroid is a(n)
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infectious piece of RNA without a capsid.