Microbiology Chapter 14.txt

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Microbiology Chapter 14.txt
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Microbiology Chapter 14
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  1. Icosahedron
    • A twenty-sided shape. It has 20 triangular faces and 12 corners.
    • Herpesvirus and poliovirus have this shape.
  2. Genome
    • The viral genome of almost all viruses contains either DNA or RNA but not both and the nucleic acid occurs in either a double or single stranded form.
    • The nucleic acid is usually a circular or linear molecule.
    • The genome is folded or coiled to make it smaller
  3. Capsid
    • The protein coat of a virus particle.
    • Gives shape and symmetry to the virus.
  4. Caspomere
    • The capsid is generally subdivided into individual protein subunits.
    • The organization of capsomeres yields the viral symmetry.
  5. Virion
    A completely assembled and infectious virus outside its host cell
  6. Bacteriophage
    • A virus that infects a bacteria.
    • They can destroy the cells they infect
    • Phage = eat
    • Identified by Felix d'Herrelle
  7. Lysogeny
    • The phage DNA integrates into the bacterial chromosome as a prophage.
    • The bacterial cell survives the infection and continues to grow and divide normally.
    • The prophage is copied into daughter cells during binary fission.
    • One way a bacteriophage can replicate itself
  8. Burst size
    The number of virions released per infected cell
  9. Provirus
    A provirus is formed when a virus integrates its DNA into a *eukaryotic* host cell and then is present in every division of the cell. This is a stable association.
  10. Cytopathic effect
    • A noticeable deterioration or structural change to the host cell when infected by a virus.
    • Assists in clinical laboratory diagnosis with a light microsope
  11. Hemagglutination
    A substance facilitating the attachment and penetration of influenza viruses into host cells
  12. Plaque
    A clear zone in the cloudy lawn of bacterial cells or monolayer of animal cells when culturing a virus.
  13. Acyclovir
    A base analog that resembles DNA bases and is a useful antiviral agent in diseases caused by DNA viruses such as herpes.
  14. Interferon
    • Interferon (IFN) is a group of naturally-produced proteins that alert cells to a viral infection.
    • Some IFNs have anti-cancer properties.
  15. Attenuated virus
    A weakened virus
  16. Tumor
    • A cell escapes the cell's cycle controlling factors and as it continues to multiply, a cluster of cells soon forms.
    • The cluster eventually yields a clone of abnormal cells referred to as a tumor.
  17. Carcinogen
    Chemical and physical agents that produce cellular changes leading to cancer.
  18. Oncogene
    Genes capable of transforming a cell when activated.
  19. Viroid
    Tiny fragments of nucleic acid known to cause diseases in crop plants.
  20. Prion
    An infectious protein lacking nucleic acid.
  21. Negri bodies
    • Cytoplasmic nucleoprotein inclusions found in the brain tissue of a rabid animal.
    • Two of the major shapes of viruses are
    • Helix and icosahedron
  22. The genome of a virus consists of
    Nucleic acid
  23. A viral capsid is divided in subunits called
    Capsomeres
  24. The organic compound of which a capsid is composed of is
    Protein
  25. Virulent virus
    Viruses that lyse the cell while carrying out the lytic cycle
  26. Endocytosis
    The virion is taken wholly into the host cell
  27. Two viruses with a complex shape are
    Smallpox and bacteriophage
  28. A complete virus outside its host cell is called a
    Virion
  29. The genome plus the capsid of a virus is its
    Nucleocapsid
  30. Two examples of diseases caused by icosahedral viruses are
    Herpesvirus and poliovirus
  31. The name given to the flexible membrane at the outer surface of some viruses is
    Envelope
  32. The portion of an unenveloped virus that stimulates the immune system of the body is the
    Capsid
  33. Functional projections of a viral envelope are referred to as
    Spikes
  34. Virus replication has been most thoroughly studied in bacterial viruses known as
    • Bacteriophage of the T-even group, T2, T4, T6.
    • These are large, complex, naked DNA virions with the characteristic head and tail of bacteriophages.
  35. The first stage of replication is _____, a process that involves specificity between bacterium and phage.
    Attachment
  36. In order for a virus to replicate, its ____ must be set free in the host cell cytoplasm.
    Nucleic acid
  37. During biosynthesis, the host cell produces ____ for manufacturing viral parts
    Enzymes
  38. The burst time for bactgeriophages averages from ___ to ___ minutes
    20 to 40
  39. The release stage of phage replication is facilitated by the enzyme
    Lysozyme
  40. For animal viruses, the viral absorption site exists on the host's
    Receptors on the plasma membrane
  41. Penetration also is different for animal viruses with fusion and ___ used as important methods of entry into the host cell cytoplasm
    Phagocytosis
  42. For some animal viruses, the nucleic acid is a ____ RNA, which acts like a messenger RNA molecule
    Positive-stranded
  43. Used for treatment of influenza
    Amantadine
  44. Alpha, beta, and gamma preins that inhibit viral replication
    Interferon
  45. Viruses that replicate at a very low rate
    Attnuated virus
  46. Stimulates ajacent thymine bases to bind together
    Ultraviolet light
  47. Reacts with free amino groups on viral nucleotides to prevent replication
    Formaldehyde
  48. Cellular granules associated with herpes simplex virus
    Lipshutz bodies
  49. Tightly wound coil resembling a spring
    Helix
  50. A bacterial virus
    Bacteriophage
  51. A phage that lyses the host cell
    Virulent
  52. Viral clumping of red blood cells
    Hemagglutination
  53. A type of base analog for treating viruses
    Acyclovir (herpes) or AZT (HIV)
  54. Viruses that cannot replicate following chemical or physical treatment
    Inactivated virus
  55. Chemicals that dissolve the lipd in the viral envolope
    Detergents
  56. Particles containing fragments of nucleic acid but no protein
    Viroids
  57. Infectious protein particles apparently without nucleic acid
    Prions
  58. Base Analog
    • Resembles thymine and during virus replication could be used when thymine should be present.
    • They insert themselves into the replicating DNA strand and block the ability of the virus to continue replicating its genome.
  59. John Enders, Thomas Weller, Fredrick Robbins
    • Worked for Children's Hospital of Boston
    • Developed a test tube medium of nutrients, salts, and pH buffers in which living animal cells could remain alive.
    • Polio cells could replicate in the living cells in huge numbers.
  60. Jonas Salk and Albert Sabin
    Adapted John Enders, Thomas Weller and Fredrick Robbins test tube medium to produce massive quantities of virus for use in polio vaccines
  61. Phage typing is useful for
    Diagnosing several bacterial diseases
  62. Base analogs prevent viral replication by
    Replacing nitrogenous bases in DNA
  63. Where is the envelope obtained from?
    • The host cell during replication.
    • It is composed primarily of lipids
  64. A virus is a biological particle composed of
    Nucleic acid and protein
  65. All viruses have
    A genome and a capsid
  66. Viruses are
    • Small, obligate intracellular parasites
    • They lack the machinery for generating energy and large molecules
    • They need a host eukaryote or prokaryote to replicate
    • The viral genome contains either DNA or RNA, but not both
  67. Genome
    • Nucleic acid core = genome
    • DNA
    • RNA
  68. Protein coat
    • capsid
    • capsomeres
  69. The capsid is
    The protein coat, made up of capsomeres
  70. The nucleocapsid is
    The capsid with its enclosed genome
  71. Spikes are
    Some capsid proteins that help the virus attach to and penetrate the host cell
  72. Naked viruses are composed of
    Only a nucleocapsid
  73. Viruses surrounded by an envelope
    Are enveloped viruses
  74. A virion is
    A completely assembled, infectious virus outside its host cell
  75. A host range refers to
    What organisms the virus can infect
  76. Host range depends
    On capsid structure
  77. Tissue tropism
    Many viruses infect certain cell or tissue types within the host
  78. Viruses occur in various shapes
    • Helix
    • Icosahedron
    • Complex
  79. Naming viruses
    • Person�s name
    • Location found
    • After disease
  80. Classification by family
    • Six DNA families
    • Thirteen RNA families
    • One miscellaneous family
    • The International Committee on Taxonomy of Viruses (ICTV) is developing a classification system
  81. DNA viruses contain
    single- or double-stranded DNA genomes
  82. RNA viruses contain
    • single- or double-stranded RNA genomes
    • + strand RNA viruses have mRNA genomes
    • � strand RNA viruses have RNA strands that would be complementary to mRNA
  83. Retroviruses are replicated
    Indirectly through a DNA intermediate
  84. The Replication of Bacteriophages Is a Five-Step Process
    • Attachment - chance
    • Penetration - lysozyme
    • Biosynthesis - makes copies
    • Maturation - assembly line
    • Lysis - release
  85. T-even group bacteriophages are
    virulent viruses that carry out a lytic cycle of infection
  86. The phage nucleic acid contains only
    A few of the genes needed for viral synthesis and replication
  87. Bacteriophage replication Phase 1
    Attachment occurs when a phage�s tail fibers match with a receptor site on the bacterium�s cell wall
  88. Bacteriophage replication Phase 2
    • Penetration occurs when the phage tail releases lysozyme to dissolve a portion of the cell wall
    • Phage DNA is injected into the bacterial cytoplasm
  89. Bacteriophage replication Phase 3
    Biosynthesis is the production of new phage genomes and capsid parts
  90. Bacteriophage replication Phase 4
    Maturation is the assembly of viral parts into complete virus particles
  91. Bacteriophage replication Phase 5
    • Release is the exit of virions from the bacterium
    • It is also called the lysis stage when the cell is ruptured
  92. Temperate phages
    • Temperate phages do not lyse the host
    • They insert their DNA into the bacterial chromosome as a prophage (lysogenic cycle)
  93. Prophage
    • Temperate phages do not lyse the host
    • They insert their DNA into the bacterial chromosome as a prophage
  94. Replication of animal viruses
    • Attachment at cell membrane
    • Penetration of whole virus
    • Uncoating by lysozymes
    • Replication: Biosynthesis and Maturation
    • Envelope acquisition
  95. Animal Virus Replication Has Similarities to Phage Replication
    • Animal viruses attach to host plasma membrane via spikes on the capsid or envelope
    • Since receptor sites vary from person to person, some people are more susceptible to a certain virus than others
  96. Animal viruses are usually taken into the cytoplasm as
    Intact nucleocapsids
  97. Uncoating is
    • The separation of the capsid from the genome
    • This occurs as some animal viruses enter the cell
  98. Replication of a DNA Animal Virus
    • 1 of 2 things after uncoating
    • 1: RNA stays in Cytoplasm and maturation and biosynthesis occurs there
    • 2: DNA moves into the nucleus.
    • 2A: Biosynthesis in the cytoplasm
    • i. the envelope comes from the nucleus and release of virus causes death of cell
    • 2B: Maturation in nucleus or cytoplasm
    • i. the envelope comes from the cell membrane and cell death isn't necessary.
  99. After the new animal viruses are assembled
    • Envelope proteins are incorporated into a cellular membrane
    • The virus buds, taking the membrane part with it as an envelope
  100. Lysogeny
    • The provirus encodes a repressor protein that prevents activation of the viral genes necessary for replication
    • It is in a state of latency
    • Retrovirus
    • Can cause transduction
  101. Latent proviruses are
    • Immune to the host body�s defenses
    • They are propagated each time the cell�s chromosome is reproduced
    • Eventually the provirus will be activated and replicate
  102. Retroviruses use reverse transcriptase
    • To transcribe their RNA to DNA
    • It can then be inserted into the host chromosome
  103. Amantadine
    Stops viral attachment
  104. Vidarabine
    • Base analog
    • Herpes simplex
  105. Acyclovir
    • Base analog
    • Genital herpes
  106. Azidothymidine
    • Base analog
    • HIV
  107. Base Analog
    • Mutated bases with nonworking nucleotides
    • Makes the virus DNA stop working so replication fails
  108. Tagamet
    • Flatwarts
    • A heartburn medication
  109. Some antivirals exist to affect:
    • viral penetration/uncoating
    • genome replication
    • maturation/release
  110. Most antivirals target the replication enzymes of the virus by
    • inserting base analogs in the replicating DNA strand
    • blocking replication of the viral genome
  111. Reverse transcriptase inhibitors
    Prevent the synthesis of DNA in retroviruses
  112. Protease inhibitors
    Impede the HIV protease that trims viral proteins in capsid construction
  113. Neuraminidase inhibitors
    • Block an enzyme in the spike of influenzaviruses
    • This prevents the release of new virions into the body
  114. Interferon (IFN) is
    • A group of naturally-produced proteins that alert cells to a viral infection
    • Only works in humans if it's from humans.
    • Pig interferon doesn't work
    • Produced by infected cell to protect nearby cells
  115. Some IFNs have
    Anti-cancer properties
  116. Cells in an antiviral state can
    Inhibit viral replication by preventing protein synthesis
  117. Antibody activity
    2nd time exposed to a virus, your body knows how to destroy the virus before you get the disease
  118. Phagocytosis
    • Cell eating
    • The body sees the infected cell and sends white blood cells to eat the infected cell
    • Free floating viruses are eaten too
  119. Viral vaccines are made from
    • Inactivated viruses
    • Attenuated viruses
    • DNA vaccines
  120. Physical agents to inactivate a virus
    • Heat
    • UV light
  121. Chemical agents to inactivate a virus
    • Formaldehyde
    • Metals
    • Phenols
    • Lipid solvents
  122. Methods of direct detection of viruses
    • Inoculations to fertilized eggs
    • Inoculations of tissue cultures
    • Observation with electron microscope
  123. Using eggs for virus detection
    • Inoculate a fertilized egg
    • Grow egg for about 4 days
    • Look for deformities in the baby chicken
  124. Indirect detection of viruses
    • Search for viral antibodies
    • Hemagglutination
    • Hemagglutination Inhibition
    • Rivers' postulate
  125. Rivers� postulates expand upon Koch�s postulates to help identify viruses
    • Filtrates of infectious material shown not to contain bacterial or other cultivatable organisms must produce the disease or its counterpart
    • Filtrates must produce specific antibodies in appropriate animals
  126. Cytology uses light microscopy to
    Examine cells for cytopathic effects (CPEs) of viral infection
  127. Viruses can be observed directly by
    Electron microscopy
  128. Lipshultz bodies
    Nuclear granules
  129. Negri bodies
    Granules in the cytoplasm
  130. Downey cells
    • Foamy cytoplasm
    • Mononucleosis
    • In white blood cells, especially lymphocytes
  131. Koplik spots
    • Red spots with patchy white centers
    • Plaque formation
    • Phage infection, clear areas on the bacterial lawn
    • A clear zone within the monolayer
  132. Cancer is an
    Uncontrolled growth and spread of cells
  133. Tumor
    • A tumor is a clone of abnormal cells
    • The body surrounds a tumor with a capsule of connective tissue
    • Benign
    • Encapsulated
    • Rapidly growing cells in a capsule
  134. Cancer
    • Malignant
    • Tumor cells can break free from the capsule and spread to other tissues of the body (metastasis)
  135. Characteristics of cancer cells
    • Dedifferentiation: lose specialization
    • Lose contact inhibition: lose ability to stop growing when they come in contact with another cell
    • Sometimes metastisizes
  136. Damage by cancer
    • Invade and erode normal tissue
    • Use vital nutrients: prevents healing
    • Release hormones
  137. Causes of cancer
    • Viruses
    • Radiation
    • Chemical carcinogens
    • Unknown factors
  138. Viruses are responsible for
    Up to 20 percent of human tumors
  139. Carcinogens are associated with
    60-90% of human cancers
  140. Epstein-Barr virus
    • Monocucleosis and chronic fatigue syndrom
    • Burkitt�s lymphoma: a tumor in the jaw
  141. Human papilloma virus (HPV)
    • Cervical cancer
    • There is now a vaccine against the 2 most common strains of HPV
  142. The oncogene theory
    Proto-oncogene: virus enters and interferes, the cell becomes an oncogene
  143. Proto-oncogene
    • Keeps track of how many times a cell has divided and tells a cell when to stop
    • If a virus is incorporated into this area it may restart the dividing process or cause uncontrollable growth
  144. Viroids
    • Fragments of nucleic acid
    • Cause plant diseases
  145. Prions
    • Proteinaceous infectious particles
    • Diseases in humans and animals
    • Spongiform encephalopathies
  146. Prions
    • 13.7 Emerging Viruses and Viral Evolution
    • Emerging Viruses Usually Arise Through Natural Phenomena
    • Emerging viruses may spread to new populations, or may expand host range
  147. Genetic recombination
    • Can lead to �new� viruses
    • Mutation can occasionally be advantageous and create a new or new strain of virus
  148. There are three hypotheses for the origin of viruses
    • Regressive evolution hypothesis
    • Cellular origins hypothesis
    • Independent entities hypothesis
  149. The regressive evolution hypothesis
    Viruses are degenerate life-forms
  150. The cellular origins hypothesis
    Viruses are derived from subcellular components and macromolecules that escaped from cell walls and replicated inside hosts
  151. The independent entities hypothesis:
    Viruses coevolved with cellular organisms from a self-replicating molecule present on primitive Earth

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