Intro To Virology- Exam III Flashcards
(119 cards)
1
Q
Compare the organization of viruses versus cellular organisms:
A
Virus= simple organization
Cellular organisms= complex organization
2
Q
Compare the genome of viruses versus cellular organisms:
A
Virus: DNA or RNA genome
Cellular organism: DNA genome and RNAs
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
4
Q
All viruses are ____, while only some cellular organisms are ___.
A
obligate intracellular parasites (both)
5
Q
According to the theory of ____ viruses evolved by degenerative evolution from intracellular parasitic cells
A
Theory of reductive origin
6
Q
The theory of of reductive origin states that viruses evolved by degenerative evolution from:
A
Intracellular parasitic cells
7
Q
The theory of reductive origin results in a:
A
DNA virus
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
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
10
Q
The theory or intracellular origin results in a:
A
retrovirus
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
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
13
Q
The theory of independent origin results in a:
A
RNA virus
14
Q
_____ virus is bigger by far than any other non virus and rivals bacteria.
A
Pandoravirus (1000nm)
15
Q
____ viruses genomes are segmented and the segments are distributed into separate viral particles
A
multicomponent viruses
16
Q
Cultivation of viruses requiresL
A
inoculation of living host cell
17
Q
What four things are required in order for a virus to inoculate a living host cell?
A
- suitable host
- enbryonated eggs
- tissue (cell) cultures
- cytopathic effects (CPEs)
18
Q
Tissue cell cultures include:
A
- monolayers of animal cells
- plaques
19
Q
Localized area of cellular destruction and lysis:
A
plaque
20
Q
microscopic or macroscopic degenerative changes or abnormality in host cells and tissues:
A
cytopathic effects (CPEs)
21
Q
A nucleocapsid:
A
naked capsid virus
22
Q
What components comprise a nucleocapsid? (naked capsid virus)
A
- DNA or RNA
- structural proteins
- enzymes & nucleic acid-binding proteins
23
Q
A nucleocapsid + glycoproteins and membrane result in:
A
enveloped virus
24
Q
Allows the virus to increase the number of structural units in each face to expand capsid size:
A
icosahedral symmetry
25
What components comprise an icosahedral virus:
1. nucleocapsid
2. capsid
3. capsomeres (proteins)
4. nucleic acid
26
What is an example of a virus that displays icosahedral symmetry?
HSV1
27
An icosahedral symmetric virus with the addition of a tail:
bacteriophage T4 capside
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virus in which the protein subunits and the nucleic acid are arranged in a helix:
helical symmetry
29
A helical virus includes:
1. nucleocapsid
2. nucleic acid
3. protein (monomeric units)
30
Give an example of a filamentous virus:
ebola
31
Compared to a non-enveloped virus, an enveloped virus contains:
1. glycoprotein spikes
2. lipid bilayer
32
Both ___ & ___ viruses can be enveloped or non-enveloped
helical & icosahedral
33
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:
asymmetrical viruses
34
Give an example of an asymmetrical virus:
vaccinia poxvirus
35
An asymmetrical virus has both:
and outer membrane & core envelope
36
Main groups of human viruses:
RNA viruses break down into:
1. nonenveloped
2. enveloped
37
Main groups of human viruses:
Non-enveloped RNA viruses break down into:
1. single stranded positive sense
2. double stranded
38
Main groups of human viruses:
Enveloped RNA viruses break down into:
1. single stranded positive sense
2. single stranded negative sense
3. retroviruses
39
Viruses are classified using a combination of properties including:
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
40
Main groups of human viruses:
DNA viruses break down into:
1. non-enveloped
2. enveloped
41
Main groups of human viruses:
DNA non-enveloped viruses break down into:
1. single-stranded linear
2. double-stranded linear
3. double-stranded circular
42
Main groups of human viruses:
DNA enveloped viruses break down into:
1. double-stranded linear
2. double-stranded circular
43
Virus replication involves: (steps)
1. adsorption
2. penetration & uncoating
3. synthesis of viral proteins and nucleic acids
4. assembly of virions
5. release
44
Step of viral replication when viral surface proteins and/or enzymes mediate attachment to specific host receptors:
adsorption of virions
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Step of viral replication three mechanisms including:
- injection of nucleic acid
- fusion of envelope with host membrane
- endocytosis
penetration and uncoating
46
Penetration and uncoating involves:
1. injection of nucleic acid
2. fusion of envelope with host membrane
3. endocytosis
47
Once the virus has entered the host cell, it will undergo synthesis of:
viral proteins and nucleic acids
48
Viral protein synthesis will require the translation of:
viral messenger RNA
49
Viral synthesis of nucleic acids will require ____ if its a DNA virus or ____ if its an RNA virus
DNA synthesis; RNA synthesis
50
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:
protein synthesis and genome replication
51
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:
translated directly into proteins
52
In a single stranded positive sense RNA virus, there is a limited amount of proteins that can be generated from:
the initial translation event
53
can act as a messenger RNA and can be directly translated into RNA proteins by a host cells ribosomes:
positive sense genome
54
Have genomes that act as complimentary strands from which messenger RNA is synthesized by the viral enzyme RNA-dependent RNA polymerase:
negative sense genome
55
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:
+ strand
56
single stranded negative sense RNA virus example:
ebola
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an example of a single stranded positive sense RNA virus:
polio virus; West Nile virus
58
Coronaviruses are categorized as:
Positive sense RNA viruses
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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:
it can copy the minus sensed genome into a plus sensed RNA genome
60
For DNA viruses, for herpes virus for example is:
circular double stranded DNA genome
61
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:
produce multiple copies of the DNA double stranded genome
62
Retroviruses come in as a:
positive sense RNA virus
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Retroviruses come in as a positive sense RNA virus but the don't get translated into proteins right away rather they go create:
a double stranded DNA copy of themselve
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The double stranded DNA copy of themselves created by retroviruses is created by:
reverse transcription
65
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:
messenger RNAs and more viral RNA
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Once you have viral proteins created and viral nucleic acids replicated, viruses need to:
assemble into new capsids
67
Capsid proteins are encoded in the viral genome and if if it is a large viral genome it will be encoded by:
late genes (genes that expressed late during infection)
68
During assembly of viral capsids often times you all have assembly of empty procapsids that then have:
nucleic acid inserted into them
69
For naked capsid viruses, the assembly of viral capsids is complete at:
assembly of empty procapsids and inserting nucleic acid into them
70
For assembly of virus capsids in enveloped viruses, they will package nucleic acid into the capsid structures to create nucleocapsids and they will:
acquire an envelope at this point
71
Once viruses are assembled, they will be:
released out into environment
72
Naked viruses are usually released by:
lysis of host cell
73
For enveloped viruses, describe virion release:
formation of envelope and release typically occur concurrently
74
During virion release of enveloped viruses, ___ are incorporated into host membrane
virus-encoded proteins
75
During virion release of enveloped viruses, ____ buds outward and is surrounded by modified host membrane
nucleocapsid
76
When looking at virus replication events during a single infectious cycle:
Once the virus attaches and enters the host cell, the virus titer:
will decrease
77
When looking at virus replication events during a single infectious cycle:
Why does the virus titer decrease after the virus enters the host cell?
because the virus has entered the host cell and is now no longer detectable in culture medium
78
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:
eclipse
79
The end of the eclipse period is marked by:
an increase in viral titers
80
At the end of the eclipse period, viruses are:
assembled and released from host cell
81
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:
1. early gene expression
2. another set of gene expression when early ramps down
3. late gene expression
82
The early gene expression seen in DNA viruses are involved in:
transcriptional regulation
83
the middle gene expression seen in DNA viruses are involved in:
genome replication
84
The late gene expression seen in DNA viruses are involved in:
encoding structural components of the capsid
85
Viral disease will vary depending on:
the virus
86
Quick infection by virus with quick expression of symptoms followed by a quick recovery or death:
acute infection
87
Encounter with the virus in which you get sick and recover all within a few days:
acute infection
88
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:
chronic infection
89
Hep B and Hep C are examples of:
chronic infections
90
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:
latent infection
91
HIV is an example of a ___ infection
latent
92
___ are considered part of the human virome
bacteriophages
93
When the bacteriophage genome reproduces progeny phage particles, as many as possible and then lysis the cell to relax them
bacteriophage lysis
94
In ___, lysogeny can occur when the phage genome integrates itself into that of the host.
Phage Lambda
95
The phage genome is replicated along with:
that of the host cell
96
The phage genome is replicated along with that of the host cell. The phage DNA however, can direct its own excision by expressing a:
site-specific DNA recombinase
97
An excised phage chromosome can initiate a:
lytic cycle
98
The botulinum toxin is encoded in:
Phage C1
99
The diphtheria toxin is encoded in:
beta phage
100
LPS synthesis (rfb) is encoded in:
Epsilon 34 (salmonella)
101
Humans contain within our genome a number of:
human endogenous retroviruses (HERV)
102
A few HERVs without our genome are extremely important in:
placental fusion
103
HERV-W provides the human protein:
Syncytin-1 (retroviral Env protein; placental fusion)
104
HERV-E provides the human protein:
apolipoprotein C1 (liver function)
105
In the ___ replication cycle, a filamentous phage produces phage particles WITHOUT lysing the cell.
slow-release replication cycle
106
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:
many of its resources are being used to make phages
107
There are some cases in which bacteria will develop a _____ including mutations in bacterial genes
genetic resistance
108
An example of genetic resistance displayed by bacteria includes:
mutations in bacterial genes (receptor for example)
109
A bacterial defense against bacteriophages that is an enzyme that cuts invading phage DNA:
restriction endonuclease
110
A piece of phage DNA gets copied as a "spacer" into the host genome:
CRISPR
111
Following insertion of the "spacer" into the host genome, if the bacterium survives and later refinfection by same kind of phage occur, this causes
transcription of spacers into CRISPR RNA
112
Following transcription of spacers into CRISPR RNA at time of reinfection, a processed spacer (crRNA) joins the Cas complex to:
recognize and cleave the phage DNA
113
____ may limit bacterial numbers to levels that the human immune system can tolerate
phages
114
A bacteria may contain a bacteriophages whose genomes are integrated into their bacterial genome, these are called:
lysogenized bacteria
115
Lysogenized bacteria may use ___ to detect host cell populations and "decide" whether to start the lytic cycle
quorum sensing
116
Lyosgenized bacteria use quorum sensing to detect host cell populations and decided wether to start:
the lytic cycle
117
Phage particles may modulate immune system activity by:
supressing T-cell activation and tumor formation
118
Phages may attack ___.
biofilms
119
Phage therapy is being explored as a potential ___
antibiotic treatment
