4 Virology Flashcards

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1
Q

what does it mean that viruses are obligate intracellular parasites?

A
  • cannot live outside living cellular host
  • cannot be treated or cured with existing medical therapies
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2
Q

name 3 hosts for viruses

A
  • plants (variegation)
  • animals
  • bacteria (bacteriophages
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3
Q

how many cell types do viruses affect?

A

one specific cell type

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4
Q

what are viroids?

A
  • smallest known pathogens
  • naked, circular, single-stranded RNA molecules that do not encode protein yet replicate autonomously when introduced to host plants
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5
Q

a viral particle is a ____

A

viron

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6
Q

viral structure consists of…

A
  • protein coat
  • nucleic acid core
  • envelope (occasionally)
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7
Q

what is the effect of a viral envelope?

A

steals plasma membrane from infected host cell, acting as camouflage from immune system

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8
Q

name 3 ways to replicate viruses

A
  • cell culture
  • fertilized eggs
  • living animals
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9
Q

the protein coat surrounding the nucleic acid core is called a ____

A

capsid

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10
Q

each capsid consists of identical protein units called ____

A

capsomeres

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11
Q

what do capsomeres do to viral structure?

A

bond together and give capsid symmetry

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12
Q

name 2 basic patterns of virus capsids

A
  • helical symmetry
  • icosahedral symmetry
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13
Q

helical symmetry

A

protein subunits and nucleic acid are arranged in a helix

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14
Q

icosahedral symmetry

A

protein subunits assemble into symmetrical shell that covers nucleic acid-containing core

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15
Q

what are the 2 nucleic acid cores and forms by which viruses are characterized?

A

DNA and RNA
(double or single stranded)

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16
Q

how many strands are in double stranded DNA?

A

4

17
Q

how many strands are in double stranded RNA?

A

2

18
Q

what are the 5 levels of viral classification?

A
  • nucleic acid
  • symmetry of capsid
  • naked or enveloped
  • type of nucleic acid
  • family name
19
Q

what is the youngest viral family?

A

filoviridae

20
Q

how are hemorrhagic fevers classified?

A

(eg. Ebola, Marburg, Lassa)
- RNA
- helical
- enveloped
- single stranded
- filoviridae

21
Q

what is the largest viral family that infects humans?

A

herpes

22
Q

what is the most stable viral form?

A

viruses with double stranded DNA genome
(eg. herpesviridae)

23
Q

what viral form is most prone to mutation?

A

viruses with + single stranded genome
(eg. Ebola, HIV)

24
Q

many viruses that infect mammals are ____

A

enveloped

25
Q

all envelopes have a ____

A

phospholipid bilayer

26
Q

envelopes arise from…

A

plasma membrane of infected host cell

27
Q

lytic infections

A

host cell fills with virions and bursts resulting in cell death

28
Q

steps in lytic infection

A
  • attachment
  • penetration
  • uncoating
  • biosynthesis
  • maturation
  • release
29
Q

virion attachment

A
  • virus binds to specific receptors on host cell (viral tropism)
  • some require co-receptors for successful attachment
30
Q

virion penetration

A
  • adhesion of virus to host receptors
  • engulfment into vesicle
  • viral RNA released from vesicle
31
Q

what is virion uncoating and what are 3 locations it can occur?

A

uncoating = removal of capsid
- at plasma membrane
- in cytoplasm
- at nuclear membrane

32
Q

virion biosynthesis

A

develop provirus (partial host DNA + viral DNA)

33
Q

virion maturation

A

involves moving newly made virions to specific sites in cell for intracellular trafficking and assembly

34
Q

what is the most important part of virion assembly?

A

placement of viral genome inside the capsid

35
Q

virion assembly

A
  • virion assembled while viral genome inside capsid
  • viral genome inserted into already-formed capsids