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Micro > CH6 pt 1 > Flashcards

CH6 pt 1 Flashcards

1
Q

scientists that said viruses are filterable agents

A
  • Ivanovski and Beijernick (cumberland filters)

- Reed (yellow fever)

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2
Q
  • non-cellular, infectious entities that have genome DNA or RNA, evolve, reproduce themselves in living cells and require a host
  • filterable agents
  • mature infectious particle
A

viruses

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3
Q

mature infectious particle that have central core of nucleic acid, capsid, and +

A

virion

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4
Q
  • protein coat that are mostly in the icosahedral or helical form
  • proteins (protomers) in clusters (capsomers)
  • many have tails attached
A

capsid

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5
Q

describe nucleic acids in viruses

A
  • packed inside capsid
  • dsDNA, dsRNA, ssDNA, ssRNA
  • circular or singular
  • single or in pieces (segmented
  • few to several hundred genes
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6
Q
  • phospholipid/ protein membrane
  • “stolen” form host cell
  • fusion (host cell entry); sensitive to environment/chemical/temp
A

envelope

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7
Q
  • glycoprotein

- for attachment

A

spikes

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8
Q
  • RNA polymerase

- reverse transcriptase (retroviruses)

A

enzymes

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9
Q

describe the replication of a virus

A
  • attachment of virion to host cell
  • entry of viral nucleocapsid
  • synthesis of viral proteins and nucleic acids
  • self-assemby of virions
  • release of progeny virons
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10
Q

how does a virus attach/absorb to host cell?

A

specific receptors on host cell

-ex: HIV will only effect if CD4 receptors present

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11
Q

vectors: insects or fungi

A

plant viruses

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12
Q
  • inject nucleic acid

- capsid remains outside, never goes in host cell

A

bacteriophage

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13
Q
  • fusion of host cell membrane with virus envelope
  • engulfed in membrane bound vesicles (endocytosis)
  • capsid digested to free nucleic acid (cytoplasm, nucleus, vesicle)
A

animal viruses

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14
Q

three types of animal virus into host cells

A
  • entry of enveloped virus by fusing with plasma membrane
  • entry of enveloped virus by endocytosis
  • entry of non-enveloped virus by endocytosis
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15
Q

describe the entry of enveloped virus by fusing with plasma membrane

A
  • viral envelope spikes bind to receptors on surface of host cell
  • lipid bilayer of viral envelope fuses with host cell membrane
  • nucleocapsid is released into cytoplasm of the host cell
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16
Q

describe entry of enveloped virus by fusing with plasma membrane

A
  • viral envelope spikes bind to receptors on surface of host cell
  • vesicle forms in cell, binding to the receptor triggers receptor- mediated endocytosis in endosome
  • increased acidity allows nucleocapsid to escape from the endosome and enter the cytoplasm
17
Q

describe entry of non-enveloped virus by endocytosis

A
  • capsid proteins bind to receptors on cell surface and trigger receptor- mediated endocytosis
  • nucleic acid is extruded from the endosome into cytoplasm
18
Q

-sequence/pathway depends on genome

A

virus synthesis

19
Q

describe DNA and ssRNA synthesis

A
  • DNA–>mRNA synthesis–> proteins

- ssRNA–>dsRNA–>provirus in host chromosomal–>mRNA synthesis–>proteins

20
Q

name early and late proteins of virus synthesis

A
  • early- taking over host cell (polymerase, regulatory proteins)
  • late- structural proteins (capside, spikes, cell lysis)
21
Q

two most common virion release

A
  • lysis of host cell-naked virus

- budding- enveloped virus

22
Q

genomes or nucleocapsids of many plant viruses also move directly from cell to cell through small connections that link to adjacent cells

A

plasmodesmata

23
Q

mechanism for releasing enveloped virions

A
  • viral envelope proteins are inserted into host cell’s plasma membrane. The viral matrix protein lines the cytoplasmic face of the plasma membrane
  • nucleocapsids are directed to the plasma membrane by host cells microtubules
  • plasma membrane protrudes outward and nucleocapsids are surrounded by matrix lined plasma membrane (budding virion)
  • neck of protruding membrane is pinched off and a mature virion is released

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