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  1. which type of cell do most known viruses infect?
  2. characteristics used for gene classification
    • genome structure
    • replication strategy
    • morphology
    • genetic relatedness
    • host range
  3. can viruses have more than one distinct nucleic acid molecule?
    yes, some do
  4. major steps in the reproduction of animal viruses
    • absorption
    • penetration and uncoating
    • replication of virus nucleic acids
    • synthesis and assembly of virions
    • virion release
  5. tropism by viruses
    virions only attach to host cells with proper receptor
  6. Name the two mechanisms that viruses use to enter a host cell
    • fusion
    • endocytosis
  7. which of the two mechanisms for virus entry involves the complete dissociation of the virus envelope with the plasma membrane?
  8. early genes
    encode proteins involved in taking over host and synthesis of viral DNA and RNA
  9. Where does viral DNA replication occur
    in the nucleus
  10. what synthesiszes the viral mRNA?
    RNA polymerase
  11. what does herpes simplex virus 1 use for the replication of the genome
    DNA polymerase
  12. How are virus capsids assembled
    capsid proteins spontaneously self-assemble to form the capsid directed by late genes
  13. 2 steps of isoahedral virus assembly
    • empty procapsids form
    • nucleic acid are inserted
  14. how to naked viruses relase
    usually by lysis of host cell
  15. envelope viruses
    formation of envelope and release  usually occur concurrently
  16. lysosome damage
    releases hydrolytic enzymes into cell
  17. alteration of the plasma membrane in a cell can lead to
    • attack of host cell by immune system
    • cell fusion, forming syncytium
  18. cytocidal infection
    infection that results in cell death
  19. chronic virus infection
    virus almost always detectable; clinical symptoms mild or absent for long periods
  20. causes of persistent infections
    • integration of the genome
    • decrease in antigenicity of virus
    • mutation to less virulent and slower reproducing form
  21. defective interefering particle
    deletion mutant that can't reproduce which slows replication of normal virus
  22. slow virus disease + example
    • symptoms take years to emerge
    • HIV
  23. tumor
    growth or lump of tissue
  24. neoplasia
    abnormal new cell growth and reproduction due to loss of cycle regulation
  25. anaplasia 
    reversion to a more primitive or less differentiated state
  26. metastasis
    spread of cancerous cells throughout body
  27. carcinogenesis involves:
    oncogenes: cancer causing genes
  28. some ways viruses can cause cancer
    • carry oncogene into cell and instert it into genome
    • promoter or DNA sequence inserted next to a cellular oncogene
    • alter cell growth due to changes in gene/protiens that regulate the cell cycle
  29. organ that hepatitus infects
  30. what does the human paplionavirus do
    cervical cancer
  31. HTLV virus causes what
  32. what kind of viruses are most plant virueses
    RNA viruses
  33. fungal  viruses are mostly what kind
  34. higher vs lower fungi
    higher is mostly latent while lower is mostly infected by virulent RNA viruses that lysis and die
  35. viral infection of insects often associated iwth what
    inclusion bodies
  36. viroids
    infectious RNA, cause plant disease, circular
  37. can virouds replicate?
    no, RNA does not encode gene products, needs a DNA host
  38. RNA silencing
    a defense mechanism that nomrally protects plant from dsRNA viruses
  39. virusoids
    infectious RNAs that enconde one or more gene products
  40. how are virusoids different from viroids?
    • encode on ore more gene products
    • need a helper virus to infect host cells and to replicate
  41. prion 
    infection protein
  42. animal diseases caused by prions
    scrapie, mad cow disease (BSE), Creutzfeldt jakob disease, Kuru
  43. PrPc and PrPSc
    • PrPc normal
    • PrPsSc is abnormal - entry of this into brain will infect normal proteins
  44. can prion diseases be treated?
Card Set:
2012-12-04 19:07:12
microbiology chapter 25

Prescott's microbiology notes for chapter 5
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