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Block 6 Week 4 Colt > Classification, Structure, and Replication of Viruses - AuCoin > Flashcards

Classification, Structure, and Replication of Viruses - AuCoin Flashcards

1
Q

T/F: viruses can pass through a filter

A

true

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2
Q

Viruses are obligate (blank)

A

intracellular parasties

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3
Q

T/F: viruses can make energy and proteins independent of a host cell

A

false

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4
Q

What are the limitations of the viral genome?

A

it can be DNA or RNA BUT NOT BOTH

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5
Q

What are the two general viral morphologies?

A

naked capsid or enveloped

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6
Q

What two processes have optimized viruses to infect humans and other hosts?

A

mutation and selection

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7
Q

What is a important characteristic of the genes a virus encodes to ensure its survival?

A

it must code for any process not provided by the host cell and its components MUST SELF ASSEMBLE

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8
Q

What types of cellular components do viruses hijack?

A

polymerases and transcription factors

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9
Q

structural proteins and enzymes and nucleic acid binding proteins all together form the (blank)

A

nucleocapsid

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10
Q

A nucleocapside and a glycoprotein and a membrane make a (blank)

A

enveloped virus

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11
Q

Papilloma virus, adenovirus, and polio viruses are all (blank) viruses

A

naked capsid viruses

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12
Q

herpesvirus and retrovirus are both (blank) viruses

A

enveloped viruses

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13
Q

Hepatitis A virus is a (blank) virus, while all other hepatitis viruses are RNA viruses

A

DNA

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14
Q

What are the means of classifying viruses?

A
  1. structure: size, morph, and nucleic acid
  2. BCH characteristics like structure and mode of rep
  3. disease (encephalitis)
  4. means of transmission
  5. tissue or organ affected
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15
Q

what is viral tropism?

A

when a virus preferentially targets a specific tissue type

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16
Q

Picornavirus is a example of (blank) naming

A

structural

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17
Q

Retroviruses is an example of (blank) naming

A

BCH

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18
Q

adenoviruses and reoviruses are examples of (blank) naming

A

tropism

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19
Q

Pox, herpes, and hepadna viruses are all (blank) DNA viruses

A

enveloped

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20
Q

Polyoma, papilloma, adeno, and parvo viruses are all (blank) DNA viruses

A

enveloped

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21
Q

Parvovirus is special because it is (ds/ss) DNA

A

ssDNA

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22
Q

+ RNA is equal to (blank)RNA

A

mRNA

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23
Q

What is the unit of measurement for viruses? How do they compare to the size of staph?

A

nanometers, 1/4 the size

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24
Q

T/F: larger virions hold larger genomes and are therefore more complex

A

true

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25
Q

What is a virion?

A

infectious particle made of nucleic acid genome packaged into a protein coat or membrane

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26
Q

Where are viral proteins packaged within the virion?

A

in the tegument layer, between the capsid and envelope

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27
Q

What is the size of poxvirus? E. coli? Human cell?

A

Poxvirus: 0.3um
E. Coli: 6.0um
Human cell: 30-100 um

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28
Q

What is the shape of the nucleocapsid in nake viruses?

A

icosahedral

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29
Q

What are the two shapes of the nucleocapsid in enveloped viruses?

A

icosahedral or helcial ribonucelocapsid

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30
Q

What makes up a ribonucleocapsid?

A

Protein and RNA together

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31
Q

The (blank) on the surface of the capsid envelope mediates the interaction of the virus and target cell

A

viral attachment protein

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32
Q

Neutralizing Abs bind to (blank) and block infection

A

viral attachment proteins

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33
Q

T/F: the capsid is a fluid structure

A

false

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34
Q

Viruses with (capsid/membrane) are resistant to drying, acid, and detergents

A

capsids

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35
Q

(Naked/enveloped) viruses can be transmitted via fecal oral or via sewage

A

naked

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36
Q

The viral envelope contains lipids, proteins, and glyco(proteins/lipids)

A

glycoproteins

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37
Q

Since the envelope is only maintained in aqueous solution, enveloped viruses are only transmitted via (blank)

A

body fluids

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38
Q

gp120 protein on HIV binding CD4 on Tcells is an example of the (blank) protein

A

viral attachment protein

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39
Q

An (icosahedral/ribonucelocapsid) is found in most negative strand RNA viruses

A

helical ribonucleocapsid

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40
Q

T/F: the helical ribonucleocapsid can self assemble

A

true

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41
Q

Vesicular stomatitis virus nucleocapsid is a good example of the (blank) structure

A

helical ribonucleocapsid

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42
Q

What two protein subunits make of the ribonucleocapsid?

A

N and M

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43
Q

The icosahedron of picornavirus, which is simple, is made of 12 (blanks) with five fold symmetry (i.e. a pentamer)

A

capsomers

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44
Q

Five protomers come together to form one (blank)

A

capsomer

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45
Q

How does something like herpesvirus create a more complex capsid?

A

by inserting structurally distinct proteins between the pentamers (capsomers)

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46
Q

what material is hijacked to make the building blocks of the viral envelope

A

cellular membrane

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47
Q

most (blanks) act as viral attachment proteins that bind to target cells to initiate entry

A

glycoproteins

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48
Q

VAPs that bind to RBCs are called (blank)

A

hemagglutinins

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49
Q

What are the spikes on viruses?

A

glycoproteins

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50
Q

T/F: cellular proteins are often found in viral membranes

A

false

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51
Q

T/F: the glycoprotein spikes on viruses are usually immunodominant

A

true

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52
Q

T/F: all negative strand RNA viruses are enveloped

A

treu

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53
Q

What is interesting about the influenza A genome?

A

it is segmented -RNA

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54
Q

The (blank) layer is betweent he envelope and nucleocapsid and contains enzymes and other proteins that facilitate viral infection

A

tegument

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55
Q

what are the processes involved in viral replication?

A 
recognition
attachment
penetration
uncoating
delivery of genome to nucleus
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56
Q

Genome replication and macromolecular synth is followed by viral (blank) and release

A

assembly

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57
Q

(blank) is when extracellular infectious virus is not detected but viral genomes can be detected

A

latency

58
Q

latency is a hallmark of what type of infection?

A

herpesvirus

59
Q

T/F: viral protein synth and genome replication happen at the same time

A

true

60
Q

what determines what cells can be infected by a virus?

A

binding of the VAP to the cell receptors

61
Q

T/F: VAPs can be proteins, CHOs, glyocproteins, or glycolipids

A

true

62
Q

what is a viral host range?

A

viruses can enter only the cells that express the right receptor type

63
Q

What macromolecule are VAPs normally?

A

glycoproteins

64
Q

The HA VAP of influenza A binds to the (blank) receptor of a broad range of cell types

A

sialic acid receptor

65
Q

What type of macromolecule is HA?

A

glycoprotein

66
Q

Most nonenveloped viruses enter the cell via (blank)

A

receptor mediated endocytosis

67
Q

T/F: enveloped viruses fuse their membrane with the cell membrane to inject the nucleocapsid into the cytosol

A

true

68
Q

at what pH are fusion proteins active?

A

neutral OR acidic conditions of the endosome following receptor mediated endocytosis

69
Q

Where are DNA genomes delivered?

A

nucleus

70
Q

Where are RNA genomes delivered?

A

cytoplasm

71
Q

T/F: both the envelope and the capsid must be removed to begin replication

A

true

72
Q

Which DNA virus does not have its DNA moved to the nucleus?

A

Pox virus

73
Q

What RNA pol does the virus use to make mRNA?

A

RNA Pol II

74
Q

what mods does viral mRNA get?

A

3’ poly A tail and 5’ methylated cap

75
Q

T/F: viruses encode the enzymes for transcription RNA dependent RNA Pol

A

true

76
Q

What is the function of the poly A tail?

A

nuclear export and mRNA stability

77
Q

What is the function of the 5’ 7-methyl-guanosine cap?

A

binds to the ribosomes

78
Q

RNA retroviruses and orthomyxovirus like influenza replicate where

A

in the nucleus!

79
Q

T/F: replication of viral DNA is semiconservative

A

true

80
Q

T/F: replication of viral DNA can be rolling circle or linear

A

true

81
Q

Describe dsDNA viral rep?

A

dsDNA to mRNA to protein

82
Q

Describe ssDNA viral rep?

A

ssDNA to dsDNA to mNRA to protein

83
Q

Describe segmented dsRNA viral rep?

A

segmented dsRNA makes mRNA from each segment

84
Q

What is the difference between the requisites at the time of infection between + and -RNA viruses?

A

-RNA needs to have a synthesized protein RNA dep. RNA pol to initiate its own transcription while +RNA can code for it and the cell’s ribosomes will make it for it

85
Q

What happens during +RNA viral translation?

A

one large polyprotein is made and is cleaved by either viral or host enzymes

86
Q

How are +RNA viruses replicated?

A

Host ribosome makes all the proteins from +RNA genome. RNA dep. RNA Pol from RNA genome makes -RNA template, from which it makes multiple +RNA genome copies for packaging

87
Q

T/F: retroviruses are integrated into the host genome

A

true

88
Q

T/F: DNA viruses are larger than RNA viruses

A

true

89
Q

some complex DNA viruses can encode their own (blank) to regulate expression of viral genes

A

transcription factors

90
Q

Viral DNA replication begins at the (blank), where viral replication factors bind, such as DNA dep DNA Pol

A

Ori

91
Q

Large DNA viruses encode their own DNA Pol which will make more (blanks) creating mutations

A

errors

92
Q

Antiviral nucleotide analogs target what?

A

viral polymerases

93
Q

immediate early genes code for:

A

transcription factors

94
Q

early genes code for:

A

protein synthesis and genome replication

95
Q

late genes code for:

A

structural proteins; glycoproteins, capsid proteins, and tegument proteins

96
Q

What two types of genes produce products that go back into the nucleus?

A

immediate early and early genes

97
Q

the signal sequence in viral mRNA will signal it to attach to ribosomes located on the (blank0

A

rER

98
Q

what types of modifications will the protein made in the rER undergo?

A

glycosylation and acetylation

99
Q

What is the fate of the cytoplasmically created structural proteins?

A

They go back into the nucleus to make the capsid.

100
Q

Where does the DNA containing naked capsid immediately go after exiting the necleus?

A

rER

101
Q

Where does the capsid gain its envelope?

A

trans golgi

102
Q

(blank) proteins will bind to the intracellular portion of the glycoprotein coat to link it to the capsid

A

tegument

103
Q

Proteins involved in cell take over are expressed in what genes?

A

IE

104
Q

DNA dep DNA pol is expressedin what type of genes?

A

early

105
Q

T/F: the genome is replicated during the transcription of the late genes

A

false; BEFORE

106
Q

What are the two methods that the virus is released from the cell?

A

exocytosis or cell lysis

107
Q

RNA viruses must code for what type of Pol?

A

RNA dep RNA pol

108
Q

What is unique about RNA dep RNA pol regarding virulence?

A

they are fast and have a high mutation rate

109
Q

T/F: viral +RNA ALONE can initiate infection

A

true

110
Q

T/F: viral -RNA ALONE can initiate infection

A

false

111
Q

except for influenza, RNA viral transcription and replication occurs in the (blank)

A

cytoplasm

112
Q

describe the fidelity of RNA dep RNA pol?

A

LOW FIDELITY

113
Q

T/F: RNA dep RNA pol has the ability to proofread

A

false, that’s why its low fidelity

114
Q

RNA dep RNA pol have a mutation rate of (blank) while DNA dep DNA pol has a mutation rate of (blank)

A

1:3000 vs 1: billion

115
Q

rhabdovirus is shaped like a (blank)

A

bullet

116
Q

L and NS proteins come together to form (blank)

A

RNA dep RNA pol

117
Q

What is the G protein, where is it modified, and how is it modified?

A

the surface glycoprotein, GLYCOSYLATED (for G) in the rER

118
Q

Where does the G protein go?

A

embeds in the plasma membrane to await viral nucelocapsid

119
Q

Discuss the formation of the envelope-nucleocapsid

A

matrix protein associates with the intracellular portion of G protein; nucleocapsid assembles and N protein also associates with the M protein intermediate.

120
Q

what three proteins make up the nucleocapsid?

A

N, L, and NS

121
Q

Does host or viral mRNA have translational priority?

A

viral mRNA

122
Q

T/F: viral mRNA can block host mRNA egress from nucleus

A

true, they can also degrade host mRNA

123
Q

What two amino acid sequence determined actions are necessary fro viral glycoproteins?

A

insertion into the rER and N-linked glycosylatoin

124
Q

Addition of sugar molecules to the nitrogen atom of asparagine (N) linked is an example of what type of mod?

A

N-linked glycosylation

125
Q

How are protease inhibitors used as antivirals?

A

they block the cleavage of polyproteins into individual functioning proteins

126
Q

Are protease inhibitors effective against segmented genomes?

A

NO, they make one-gene-one-protein style translation, so no polyprotein

127
Q

T/F: viral membranes contain host proteins since they got their membrane from the plasma membrane

A

false!

128
Q

When the concentration of viral proteins is sufficiently high, what three types of protein-(blank) interactions occur>?

A

protein-nucleic acid
protein-protein
protein-membrane

129
Q

(blank) only occurs after the association of the nucleocapsid with the intracellular portion of G protein

A

budding

130
Q

Where do most RNA viruses bud?

A

from the plasma membrane

131
Q

besides the PM, where else can viruses bud from?

A

ER or the golgi

132
Q

what are the three methods that a virus can be released from a cell?

A

cell lysis, exocytosis, or budding from the plasma membrane

133
Q

Naked capsid viruses take what route of cell exit?

A

lysis–the membrane is broken so you can’t use it to form an envelope

134
Q

What is the only step in viral capsid assembly that requires ATP?

A

insertion of the genome into the capsid

135
Q

What two proteins can the G protein bind to?

A

the M protein or directly to the riboproteins on the RNA

136
Q

T/F: mutated viruses by definition change the phenotype, are more detrimental, and enhance pathogenicity and drug resistance

A

false; just means that they’re different that wild type

137
Q

what happens if you have a mutation in an essential gene?

A

it is lethal to the virus

138
Q

attenuated mutants cause (more/less) disease

A

less

139
Q

New virus STRAINS can be produced by intermolecular exchange (aka blank) between viruses OR VIRUS AND THE HOST

A

recombination

140
Q

What is viral reassortment?

A

when a segmented viral genome shuffles its segments if more than one viral strain is present in the host cell

141
Q

the ideal host is a (blank) host

A

naive

142
Q

100nm is how many angstroms?

A

10A

Block 6 Week 4 Colt (10 decks)

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