chapter 10

  1. Obligate intracellular parasites
    • An organism or virus that can live or multiply only inside a living host cell
    • i.e. chlamydias and rickettsias
  2. What are the components of a virus?
    • Nucleic acid
    • Capsid
    • Envelope
  3. A nucleic acid core and a surrounding protein coat is called a _?
  4. Some viruses have a lipid bilayer membrane called an _?
  5. A complete virus particle including its envelope is called a _?
  6. what is a genome?
    genetic information in an organism
  7. each capsid is composed of protein subunits called _?
  8. What do enveloped viruses have outside thier capsid?
    a typical bilayer membrane
  9. what is a nucleocapsid?
    the nucleic acid and capsid of a virus
  10. A virus with only a nucleocapsid and without an envelope
  11. projections extending from the envelope?
  12. What are spikes made of?
    glycoproteins that serve to attach virions to specific receptor sites
  13. What is the most common polyhedral capsid shape?
  14. complex viruses have a more elaborate _?
    coat or capsid
  15. viruses that infect bacteria
  16. what is host range
    referst to the spectrum of hosts that a virus can infect.
  17. refers to the specific kinds of cells a virus can infect
    viral specificity
  18. what is the ICTV
    International Committee on Taxonomy of Viruses
  19. what is viridae
    family name
  20. what are the positive sense, single stranded RNA viruses that cause human diseases
    Polio, Common cold, Hep A, Rubella/german measles, equine encephalitis, yellow fever, adult leukemia, tumors, AIDS
  21. What are the negative sense, single stranded RNA viruses that cause human diseases
    Measles, rabies, Influenza A and B, Marburg, Ebola, Respiratory distress, hemorrhagic fevers
  22. What are the double stranded RNA viruses that cause human disease
    respiratory and gastrointestinal infections
  23. What are the double stranded DNA viruses that cause human disease
    respiratory infections, oral and genital herpes, chickenpox, shingles, smallpox, cowpox, warts, cervical and penile cancers, hepatitis B
  24. What are the single stranded DNA viruses that cause human disease
    fifths disease in children
  25. Does DNA or RNA mutate?
    • RNA mutate because there is no spell checker
    • DNA has a spell checker to cut out mutants
  26. What are emerging viruses
    viruses that were perviously endemic (low levels of infection in localized area) or had crossed species barriers
  27. What are the steps in viral replication
    • 1) adsorption - attachment of virus to host cell
    • 2) Penetration - entry of virion
    • 3) synthesis - of new nucleic acid molecules & capsid protien using the cell machinery
    • 4) maturation - assembly of newly synthesized viral components
    • 5) release - departure of new virions from host cells
  28. The use of highly specific viruses that attack only the targeted bacteria and leave potentially beneficial bacteria that normally inhabit the human digestive tract and other locations alive.
    • Phage therapy
    • bacteriophage therapy
  29. What is growth measured by?
    by # not size
  30. the period during which viruses have absorbed to and penetrated host cells but cannot yet be detected in cells
    eclipse period
  31. period of a bacteriophage growth curve that spans the time from penetration through biosynthesis
    latent period
  32. plaque assay
    A viral assay used to determine viral yield by culturing viruses on a bacterial lawn and counting plaques

    count the spots that growth was killed
  33. A plaque forming unit PFU
    a plaque counted on a bacterial lawn that gives only an approximate number of phages present, because a given plaque may have been due to more than one phage
  34. A bacteriophage that does not cause a virulent infection; rather its DNA is incorporated into host cells chromosome, as a prophage, and replicated with the chromosome
    temperate phage
  35. a stable, long term relationship between the phage and its host in which the phage nucleic acid becomes incorporated into the host nucleic aicd
  36. The viral DNA within the bacterial chromosome
  37. the combination of temperate phage and bacterium
  38. The ability of a prophage to prevent additional infections of the same cell by the same type of phage; also the conversion of a non-toxic-producing bacterium into a tonix-producing one by a temperate phage
    lysogenic conversion
  39. Which cycle is the virulent cycle
    lytic cycle
  40. what cycle may stay hidden forever or breaks out into virulent
    lysogenic cycle
  41. Culture made from a single tissue, assuring a reasonably homogeneous set of cultures in which to test the effects of a virus or to culture an organism
    tissue culture
  42. A culture in the form of a monolayer from dispersed cells and continous cultures of cell suspension
    Cell culture
  43. A suspension of cells that attach to plastic or glass as a sheet one layer thick
  44. The process by which cells from an existing culture are transferred to new containers with fresh nutrient media
  45. come directly from the animal and are not subcultured
    primary cell cultures
  46. If primary cell cultures are repeatedly subcultured, one cell type will become dominant, and the culture is called a _.
    cell strain
  47. The visible effect viruses have on cells
    cytopathic effect, CPE
  48. The introduction of defects during embryonic development
  49. a drug or other agent that induces defects into the fetus
  50. series of blood tests, sometimes used to identify possible teratogenic diseases in pregnant women and newborn infants.
    TORCH series
  51. AKA virusoids, small single-stranded RNA molecules that lack genes required for their replication. they require a helper virus (or satellite) to replicate
    satellite nucleic acids
  52. Small single stranded RNA molecules, usually 500 to 2,000 nucleotides in length, which lack genes required for their replication. They require a helper (satellite) to replicate
    satellite virus
  53. an infectious RNA particle smaller than a virus
    (short strips of RNA that cause color changes in plants)
  54. Viroids differ from viruses in 6 differet ways
    • 1) each viriod consist of a singular circular RNA molecule of low molecular weight, 246 to 399 nucleotides in length
    • 2) Viroids exist inside cells, usually inside of nucleoli, as part of RNA without capsids or envelopes
    • 3) Unlike viruses such as the parvoviruses, viroids do not require a helper virus
    • 4) viroid RNA does not produce proteins
    • 5) unlike virus RNA, which may be copied in the host cell's cytoplasm or nucleus, viroid RNA is always copied in the host cell nucleus
    • 6) Viroid particles are not apparent in infected tissue without the use of special techniques to idenitfy nucleotides sequence in the RNA
  55. an exceedingly small infectious particle consisting of protein without any nucleic acid
  56. list some prions we talked about in class
    • Cruetzfeldt-Jakob disease
    • kuru
    • scrapie
    • bovine spongiform encephalopathy - mad cow disease
  57. What are the 5 characteristics of prions
    • 1) prions are resistant to inactivation by heating to 90C, which will inactivate viruses
    • 2) prion infection is not sensitive to radiation treatment that damages virus genomes
    • 3) Prions are not destroyed by enzymes that digest DNA or RNA
    • 4) prions are sensitive to protein denaturing agents such as phenol and urea
    • 5) prions have direct pairing of amino acids
  58. what are virus nucleic acids and hosts
    • ssDNA
    • dsDNA
    • ssRNA
    • dsRNA

    effects - bacteria, animals, plants
  59. what are the nucleic acid and host of viroids

    effects - plants
  60. what are the nucliec acids and hosts of prions
    no nucleic acid

    effects mammals
  61. uncontrolled, invasive growth of abnormal cells
  62. localized accumilation of cells known as a tumor
  63. non-cancerous growth
  64. cells that invade and interfere with the functioning of surrounding normal tissue
  65. malignant tumors and their cells can spread to other body tissues
  66. the proteins produced by tumor viruses that cause incontrolled host cell division come from segments of DNA called_
  67. surrounding protein coat
  68. complete virus particle, including envelope if it has one
  69. projection made of gylcoproteins that serves to attach virions to specific receptor sites
  70. surrounding lipid bialyer membrane
  71. virus with a nucleocapsid but no envelope
    naked virus
  72. virions genome together with capsid
  73. a chemical component that is found in all viruses is:

    A) protein
  74. a common polyhedral capsid shape of viruses is:

    A) icosahedron
  75. true or false:
    viruses are capable of infecting all life forms; some can even infect members of different kingdoms but most are limited to only one host and olny specific cells and/or tissue of that host
  76. enteroviruses differ from rhinoviruses mainly in thier

    B) ability to survive acidic conditions
  77. Which of the following proterites do viruses have in common with the bacterial section containing Reckettsiae and Chlamydiae.

    C) they are both obligate intracellular parasites
  78. viruses that remain latent (usually in neurons) for many years are most likely:

    A) herpesviruses
  79. what type of viruses contain the enzymes lysosome to aid in their infection:

    E) bacteriophages
  80. viruses that infect bacteria are called:

    A) bacertiophages
  81. bacteriophages are readily counted by the process of:

    B) plaque assay
  82. the type of cell culture that can be reproduced for an extended number of generations and is used to support viral replication is:

    B) continuous cell line
  83. Which of the following is not a DNA virus:

    C) orthomyxovirus
  84. what are the general replication steps in order
    • 1) adsorption - attachment of virus to host cell
    • 2) penetration - entry of virion genome into host cell
    • 3) synthesis - host metabolic machinery is used to produce new nucleic acid molecules, capsid proteins, and other viral components
    • 4) maturation - assembly of newly synthesized viral components into complete virions.
    • 5) release - departure of new virions from host cell, generally with lysis of host cell
  85. bacteriophages that can enter into stable, long-term relationships with their hosts are called:

    D) temperate phages
  86. the positive (+) strand RNA of certain viruses does not act as a message but becomes converted into DNA and integrated into the host cellular DNA. These viruses are:

    C) retroviruses
  87. immortalized cells that produce for an extended number of generations
    continuous cell line
  88. cells that come directly from the animal, have very few cell divisions, but support the growth of a wide variety of viruses
    primary cell culture
  89. trypsinized and washed cells that attach to plastic surfaces where they mulitply and spread to form sheets one cell thick
  90. cells from an existing cell culture are transferred to new containers with fresh nutrient media
  91. visible effects viruses produce in infected host cells
    cytopathic effect CPE
  92. immature, fetally derived cell types that rapidly divides numerous times and supports a wide range of viruses
    diploid fibroblast strain
  93. Creutzfeldt-Jakob disease (CDJ), kuru, scrapie, and mad cow disease are caused by:

    D) prions
  94. The human virus that has been associated with Burkett's lymphoma (a malignant tumor of the jaw) is:

    C) epstein-barr virus
  95. infectious, incorrectly folded protein
  96. small, single-stranded RNA virus lacking genes required for tis replication, and needing a helper virus
  97. helper virus codes for its capsid
  98. code for their own capsid protein
    satellite viruses
  99. infectious RNA particles smaller than a virus
  100. similar to a viroid and virusoids, a defective pathogen requiring the presence of hepatitis B virus for its replication
    delta hepatitis virus
  101. viruses that can induce defects during embryonic development (teratogenesis) in humans:

    B) a, b, and d
  102. eclipse period, latent period and viral yield
    • eclipse period - period during which viruses have absorbed to and penetrated host cells but cannot yet be detected in cells.
    • latent period - period of a bacteriophage growth curve that spans from the time of penetration through biosynthesis
    • viral yield - AKA burst size - the number of new virions released in the replication process
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chapter 10