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microbiology > Intro To Virology- Exam III > Flashcards

Intro To Virology- Exam III Flashcards

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1
Q

Compare the organization of viruses versus cellular organisms:

A

Virus= simple organization

Cellular organisms= complex organization

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2
Q

Compare the genome of viruses versus cellular organisms:

A

Virus: DNA or RNA genome

Cellular organism: DNA genome and RNAs

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3
Q

Describe the reproduction of viruses compared to cellular organisms:

A

viruses are unable to reproduce outside living cells

cellular organisms carry out cell division

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4
Q

All viruses are ____, while only some cellular organisms are ___.

A

obligate intracellular parasites (both)

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5
Q

According to the theory of ____ viruses evolved by degenerative evolution from intracellular parasitic cells

A

Theory of reductive origin

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6
Q

The theory of of reductive origin states that viruses evolved by degenerative evolution from:

A

Intracellular parasitic cells

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7
Q

The theory of reductive origin results in a:

A

DNA virus

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8
Q

According to the theory of ___, viruses evolved from functional parts of cells that acquired an ability to reproduce themselves uncontrolled by the cell

A

theory of intracellular origin

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9
Q

According to the theory of intracellular origin, this states that viruses evolved from ____ and acquired an ability to ___ uncontrolled by the cell.

A

functional parts of cells; reproduce themselves

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10
Q

The theory or intracellular origin results in a:

A

retrovirus

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11
Q

The theory of ____ hold that viroid nucleic acids could have evolved outside of cells during the “RNA world” and acquired the ability to infect cells

A

independent origin

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12
Q

The theory of independent origin hold that ____ could have evolved outside of cells during the “RNA world” and acquired the ability to infect cells

A

viroid nucleic acids

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13
Q

The theory of independent origin results in a:

A

RNA virus

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14
Q

_____ virus is bigger by far than any other non virus and rivals bacteria.

A

Pandoravirus (1000nm)

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15
Q

____ viruses genomes are segmented and the segments are distributed into separate viral particles

A

multicomponent viruses

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16
Q

Cultivation of viruses requiresL

A

inoculation of living host cell

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17
Q

What four things are required in order for a virus to inoculate a living host cell?

A
  1. suitable host
  2. enbryonated eggs
  3. tissue (cell) cultures
  4. cytopathic effects (CPEs)
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18
Q

Tissue cell cultures include:

A
  1. monolayers of animal cells
  2. plaques
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19
Q

Localized area of cellular destruction and lysis:

A

plaque

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20
Q

microscopic or macroscopic degenerative changes or abnormality in host cells and tissues:

A

cytopathic effects (CPEs)

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21
Q

A nucleocapsid:

A

naked capsid virus

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22
Q

What components comprise a nucleocapsid? (naked capsid virus)

A
  1. DNA or RNA
  2. structural proteins
  3. enzymes & nucleic acid-binding proteins
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23
Q

A nucleocapsid + glycoproteins and membrane result in:

A

enveloped virus

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24
Q

Allows the virus to increase the number of structural units in each face to expand capsid size:

A

icosahedral symmetry

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25
Q

What components comprise an icosahedral virus:

A
  1. nucleocapsid
  2. capsid
  3. capsomeres (proteins)
  4. nucleic acid
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26
Q

What is an example of a virus that displays icosahedral symmetry?

A

HSV1

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27
Q

An icosahedral symmetric virus with the addition of a tail:

A

bacteriophage T4 capside

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28
Q

virus in which the protein subunits and the nucleic acid are arranged in a helix:

A

helical symmetry

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29
Q

A helical virus includes:

A
  1. nucleocapsid
  2. nucleic acid
  3. protein (monomeric units)
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30
Q

Give an example of a filamentous virus:

A

ebola

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31
Q

Compared to a non-enveloped virus, an enveloped virus contains:

A
  1. glycoprotein spikes
  2. lipid bilayer
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32
Q

Both ___ & ___ viruses can be enveloped or non-enveloped

A

helical & icosahedral

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33
Q

Viruses that are referred to as complex because they posses a capsid that is neither purely helical nor purely icosahedral and may posses extra structures such a protein tails or complex outer walls:

A

asymmetrical viruses

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34
Q

Give an example of an asymmetrical virus:

A

vaccinia poxvirus

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35
Q

An asymmetrical virus has both:

A

and outer membrane & core envelope

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36
Q

Main groups of human viruses:

RNA viruses break down into:

A
  1. nonenveloped
  2. enveloped
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37
Q

Main groups of human viruses:

Non-enveloped RNA viruses break down into:

A
  1. single stranded positive sense
  2. double stranded
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38
Q

Main groups of human viruses:

Enveloped RNA viruses break down into:

A
  1. single stranded positive sense
  2. single stranded negative sense
  3. retroviruses
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39
Q

Viruses are classified using a combination of properties including:

A
  1. Type and structure of nucleic acid used for viral genome
  2. Presence or absence of an envelope
  3. Type of capsid symmetry
  4. Replication strategy
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40
Q

Main groups of human viruses:

DNA viruses break down into:

A
  1. non-enveloped
  2. enveloped
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41
Q

Main groups of human viruses:

DNA non-enveloped viruses break down into:

A
  1. single-stranded linear
  2. double-stranded linear
  3. double-stranded circular
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42
Q

Main groups of human viruses:

DNA enveloped viruses break down into:

A
  1. double-stranded linear
  2. double-stranded circular
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43
Q

Virus replication involves: (steps)

A
  1. adsorption
  2. penetration & uncoating
  3. synthesis of viral proteins and nucleic acids
  4. assembly of virions
  5. release
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44
Q

Step of viral replication when viral surface proteins and/or enzymes mediate attachment to specific host receptors:

A

adsorption of virions

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45
Q

Step of viral replication three mechanisms including:
- injection of nucleic acid
- fusion of envelope with host membrane
- endocytosis

A

penetration and uncoating

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46
Q

Penetration and uncoating involves:

A
  1. injection of nucleic acid
  2. fusion of envelope with host membrane
  3. endocytosis
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47
Q

Once the virus has entered the host cell, it will undergo synthesis of:

A

viral proteins and nucleic acids

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48
Q

Viral protein synthesis will require the translation of:

A

viral messenger RNA

49
Q

Viral synthesis of nucleic acids will require ____ if its a DNA virus or ____ if its an RNA virus

A

DNA synthesis; RNA synthesis

50
Q

Depending on the particular virus and its genome structure entering the host cells, you will end up with all kinds of different mechanisms that the different viruses engage in to carry out their:

A

protein synthesis and genome replication

51
Q

For a SS RNA virus that has a positive sense RNA genome (a genome that could be read directly as mRNA) you can see that typically when that genome enters the host cell it will be:

A

translated directly into proteins

52
Q

In a single stranded positive sense RNA virus, there is a limited amount of proteins that can be generated from:

A

the initial translation event

53
Q

can act as a messenger RNA and can be directly translated into RNA proteins by a host cells ribosomes:

A

positive sense genome

54
Q

Have genomes that act as complimentary strands from which messenger RNA is synthesized by the viral enzyme RNA-dependent RNA polymerase:

A

negative sense genome

55
Q

In a single stranded positive sense RNA virus, there is a limited amount of proteins that can be generated from the initial translation event, so the early proteins created will mediate copying of the + stranded genome to a - strand and then using the - strand as a template to create many many more copies of the:

A

+ strand

56
Q

single stranded negative sense RNA virus example:

A

ebola

57
Q

an example of a single stranded positive sense RNA virus:

A

polio virus; West Nile virus

58
Q

Coronaviruses are categorized as:

A

Positive sense RNA viruses

59
Q

For a single stranded negative sense RNA virus, their genome cannot be read as messenger RNA as it enter the host cell, it needs to bring an enzyme along with it when it enters the host cell, so the viral enzyme has to be packaged as part of the infectious virus so when it enters the host cell:

A

it can copy the minus sensed genome into a plus sensed RNA genome

60
Q

For DNA viruses, for herpes virus for example is:

A

circular double stranded DNA genome

61
Q

For DNA viruses- herpes virus is a circular double stranded genome, the fact that its a double stranded DNA genome means that it will produce messenger RNA that will then go on to be translated into proteins and it will replicate the double stranded DNA genome much the way we do, to:

A

produce multiple copies of the DNA double stranded genome

62
Q

Retroviruses come in as a:

A

positive sense RNA virus

63
Q

Retroviruses come in as a positive sense RNA virus but the don’t get translated into proteins right away rather they go create:

A

a double stranded DNA copy of themselve

64
Q

The double stranded DNA copy of themselves created by retroviruses is created by:

A

reverse transcription

65
Q

Following the reverse transcription performed by retroviruses to create a double stranded copy of DNA form the initial single stranded positive sense mRNA, they then put this copy into the host genome and then go thorough the production of:

A

messenger RNAs and more viral RNA

66
Q

Once you have viral proteins created and viral nucleic acids replicated, viruses need to:

A

assemble into new capsids

67
Q

Capsid proteins are encoded in the viral genome and if if it is a large viral genome it will be encoded by:

A

late genes (genes that expressed late during infection)

68
Q

During assembly of viral capsids often times you all have assembly of empty procapsids that then have:

A

nucleic acid inserted into them

69
Q

For naked capsid viruses, the assembly of viral capsids is complete at:

A

assembly of empty procapsids and inserting nucleic acid into them

70
Q

For assembly of virus capsids in enveloped viruses, they will package nucleic acid into the capsid structures to create nucleocapsids and they will:

A

acquire an envelope at this point

71
Q

Once viruses are assembled, they will be:

A

released out into environment

72
Q

Naked viruses are usually released by:

A

lysis of host cell

73
Q

For enveloped viruses, describe virion release:

A

formation of envelope and release typically occur concurrently

74
Q

During virion release of enveloped viruses, ___ are incorporated into host membrane

A

virus-encoded proteins

75
Q

During virion release of enveloped viruses, ____ buds outward and is surrounded by modified host membrane

A

nucleocapsid

76
Q

When looking at virus replication events during a single infectious cycle:

Once the virus attaches and enters the host cell, the virus titer:

A

will decrease

77
Q

When looking at virus replication events during a single infectious cycle:

Why does the virus titer decrease after the virus enters the host cell?

A

because the virus has entered the host cell and is now no longer detectable in culture medium

78
Q

When looking at virus replication events during a single infectious cycle:

The period after the virus enters the host cell and while its replicating within the host cell but prior to the production and release of new virus:

A

eclipse

79
Q

The end of the eclipse period is marked by:

A

an increase in viral titers

80
Q

At the end of the eclipse period, viruses are:

A

assembled and released from host cell

81
Q

For DNA viruses in particular, many of them will have larger genomes and they will undergo a pattern of gene expression in which you have:

A
  1. early gene expression
  2. another set of gene expression when early ramps down
  3. late gene expression
82
Q

The early gene expression seen in DNA viruses are involved in:

A

transcriptional regulation

83
Q

the middle gene expression seen in DNA viruses are involved in:

A

genome replication

84
Q

The late gene expression seen in DNA viruses are involved in:

A

encoding structural components of the capsid

85
Q

Viral disease will vary depending on:

A

the virus

86
Q

Quick infection by virus with quick expression of symptoms followed by a quick recovery or death:

A

acute infection

87
Q

Encounter with the virus in which you get sick and recover all within a few days:

A

acute infection

88
Q

Viral encounter followed by an initial period of illness, and then having the virus be maintained within the body which will result with chronic disease symptoms for months and years:

A

chronic infection

89
Q

Hep B and Hep C are examples of:

A

chronic infections

90
Q

An initial encounter with symptoms early on, then the symptoms disappear, but the virus is dormant and replicating in the body and later on you can experience a flare up of viral replication and infection or further progression of the virus:

A

latent infection

91
Q

HIV is an example of a ___ infection

A

latent

92
Q

___ are considered part of the human virome

A

bacteriophages

93
Q

When the bacteriophage genome reproduces progeny phage particles, as many as possible and then lysis the cell to relax them

A

bacteriophage lysis

94
Q

In ___, lysogeny can occur when the phage genome integrates itself into that of the host.

A

Phage Lambda

95
Q

The phage genome is replicated along with:

A

that of the host cell

96
Q

The phage genome is replicated along with that of the host cell. The phage DNA however, can direct its own excision by expressing a:

A

site-specific DNA recombinase

97
Q

An excised phage chromosome can initiate a:

A

lytic cycle

98
Q

The botulinum toxin is encoded in:

A

Phage C1

99
Q

The diphtheria toxin is encoded in:

A

beta phage

100
Q

LPS synthesis (rfb) is encoded in:

A

Epsilon 34 (salmonella)

101
Q

Humans contain within our genome a number of:

A

human endogenous retroviruses (HERV)

102
Q

A few HERVs without our genome are extremely important in:

A

placental fusion

103
Q

HERV-W provides the human protein:

A

Syncytin-1 (retroviral Env protein; placental fusion)

104
Q

HERV-E provides the human protein:

A

apolipoprotein C1 (liver function)

105
Q

In the ___ replication cycle, a filamentous phage produces phage particles WITHOUT lysing the cell.

A

slow-release replication cycle

106
Q

In the slow release replication cycle, a filamentous phage produces phage particles without lysing the cell and the host continues to reproduce itself, but more slowly than uninfected cells do because:

A

many of its resources are being used to make phages

107
Q

There are some cases in which bacteria will develop a _____ including mutations in bacterial genes

A

genetic resistance

108
Q

An example of genetic resistance displayed by bacteria includes:

A

mutations in bacterial genes (receptor for example)

109
Q

A bacterial defense against bacteriophages that is an enzyme that cuts invading phage DNA:

A

restriction endonuclease

110
Q

A piece of phage DNA gets copied as a “spacer” into the host genome:

A

CRISPR

111
Q

Following insertion of the “spacer” into the host genome, if the bacterium survives and later refinfection by same kind of phage occur, this causes

A

transcription of spacers into CRISPR RNA

112
Q

Following transcription of spacers into CRISPR RNA at time of reinfection, a processed spacer (crRNA) joins the Cas complex to:

A

recognize and cleave the phage DNA

113
Q

____ may limit bacterial numbers to levels that the human immune system can tolerate

A

phages

114
Q

A bacteria may contain a bacteriophages whose genomes are integrated into their bacterial genome, these are called:

A

lysogenized bacteria

115
Q

Lysogenized bacteria may use ___ to detect host cell populations and “decide” whether to start the lytic cycle

A

quorum sensing

116
Q

Lyosgenized bacteria use quorum sensing to detect host cell populations and decided wether to start:

A

the lytic cycle

117
Q

Phage particles may modulate immune system activity by:

A

supressing T-cell activation and tumor formation

118
Q

Phages may attack ___.

A

biofilms

119
Q

Phage therapy is being explored as a potential ___

A

antibiotic treatment

microbiology (24 decks)

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