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Microbiology > Chapter 31 - Intro to Virology and Phage > Flashcards

Chapter 31 - Intro to Virology and Phage Flashcards

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Biology 101 flashcards
1
Q

describe viruses

A
  • simple organization
    -DNA or RNA genome
  • unable to reproduce outside of living cells
  • obligate intracellular parasites
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2
Q

describe cellular organisms

A
  • complex organization
  • DNA genome and RNAs
  • carry out cell division
  • some are obligate intracellular parasites
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3
Q

what are the 3 theories of viral origin

A
  • reductive origin: viruses evolved by degenerative evolution from intracellular parasitic cells
  • theory of intracellular origin: viruses evolved from functional parts of cells that acquired an ability to reproduce themselves uncontrolled by the cell
  • theory of independent origin holds that viroid nucleic acids could have evolved outside of cells during the RNA world and acquired the ability to infect cells
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4
Q

how big are pandoraviruses

A

1000nm

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5
Q

what is the biggest virus

A

pandora virus

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6
Q

multicomponent viruses genomes are segmented and the segments are distributed into _____

A

separate viral particles

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7
Q

cultivation of viruses requires inoculation of living host cells. what are examples of the host cells

A
  • suitable animals
  • embryonated eggs
  • tissue cultures
  • cytopathic effects (CPEs)
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8
Q

what can tissue (cell) cultures be

A
  • monolayers of animal cells
  • plaques: localized area of cellular destruction and lysis
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9
Q

what are cytopathic effects (CPEs)

A

microscopic or macroscopic degenerative changes or abnormalities in host cells and tissues

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10
Q

what makes up a nucleocapsid/naked capsid virus

A
  • DNA or RNA + structural proteins +/- enzymes and nucleic acid binding proteins
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11
Q

what makes up an enveloped virus

A

nucleocapsid + glycoproteins and membrane

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12
Q

what makes up icosahedral symmetry

A
  • nucleocapsid made of
  • capsid
  • capsomers
  • nucleic acids
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13
Q

what virus has icosahedral capsid symmetry

A

herpes

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14
Q

what is an example of a virus with helical symmetry

A

ebola virus filaments (SEM)

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15
Q

what do enveloped viruses have vs nonenveloped

A

glycoprotein spikes and lipid bilayer

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16
Q

what is an example of an asymmetrical virus

A

vaccinia poxvirus

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17
Q

what are the groups of RNA viruses

A

nonenveloped vs enveloped

18
Q

what are the groups of nonenveloped RNA viruses

A

-single stranded positive sense
- double stranded

19
Q

what are the groups of enveloped RNA viruses

A

-single stranded positive sense
- single stranded negative sense
- retrovirus

20
Q

what properties are used to classify viruses

A
  • type and structure of nucleic acid used for viral genome
  • presence or absence of envelope
  • type of capsid symmetry
  • replication strategy
21
Q

what are the groups of DNA viruses

A

nonenveloped and enveloped

22
Q

what are the groups of nonenveloped DNA viruses

A
  • single stranded linear
  • double stranded linear
  • double stranded circular
23
Q

what are the groups of enveloped DNA viruses

A
  • double stranded linear
  • double stranded circular
24
Q

what are the steps of virus replication

A
  • adsorption
  • penetration and uncoating
  • synthesis of viral proteins and nucleic acids
  • assembly of virons
  • release
25
Q

what is adsorption of virions

A

viral surface proteins and/or enzymes mediate attachment to specific host receptors

26
Q

what are the 3 mechanisms of penetration and uncoating

A
  • injection of nucleic acid
  • fusion of envelope with host membrane
  • endocytosis
27
Q

describe the assembly of virus capsids

A
  • capsid proteins: encoded by late genes
  • assembly of naked viruses: empty procapsids formed then nucleic acid inserted
  • assembly of enveloped viruses: similar to assembly of naked viruses
  • site of morphogenesis varies
28
Q

describe virion release of naked viruses and enveloped viruses

A
  • naked viruses: usually by lysis of host cells
  • enveloped viruses: formation of envelope and release usually occur concurrently
29
Q

what are virus encoded proteins incorporated into

A

host membrane

30
Q

what are the virus replication events during a single infectious cycle

A
  • attachment
  • disassembly
  • replication
  • assembly
31
Q

which type of infection has the highest number of virus in tissues: acute, chronic or latent

A

acute then chronic then latent

32
Q

what are other principles of viral disease

A
  • viral spread and replication
  • host factors in defense and damage
  • diagnosis
  • emerging viruses
33
Q

are bacteriophages a part of the human virome

A

yes

34
Q

what is the bacterial product from prophage “phage C1”

A

botulinum toxin

35
Q

what is the bacterial product of beta phage

A

diptheria toxin

36
Q

what is the bacterial product of epsilon 34

A

LPS synthesis

37
Q

what is the human protein or regulator provided by HERV-W

A

syncythin 1

38
Q

what is the human protein or regulator provided by HERV-E

A

apolipoprotein C1

39
Q

describe the bacteriophage replication cycle: slow release

A

a filamentous phage produces phage particles without lysing the cell
- the host continues to reproduce itself but more slowly than uninfected cells because many of its resources are being used to make phages

40
Q

what are the bacterial defenses against bacteriophages

A
  • genetic resistance- mutations in bacterial genes
  • restriction endonucleases- enzymes that cut invading DNA
  • CRISP- a bacterial immune system
41
Q

why is phage therapy being explored as antibiotic treatment

A
  • phages may limit bacterial numbers to levels that the immune system can tolerate
  • phage particles may modulate immune system activity
  • phages may attack biofilms

Microbiology (39 decks)

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