Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

BIO 315 > Module 10 - Viral Replication Strategies > Flashcards

Module 10 - Viral Replication Strategies Flashcards

You may prefer our related Brainscape-certified flashcards:
Biology 101 flashcards
1
Q

In order to replicate, what must all viruses do?

A
  1. Recognize host cells
  2. Make genome available to host cell machinery
  3. Replicate genome
  4. Make multiple copies of required proteins
  5. Assemble new viral particles
  6. Exit the cell
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What is the consequence of viruses having a narrow host range?

A

They can only infect and replicate within specific cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What determines the host range of a virus?

A

The interactions between viral and cellular proteins

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What does the viral attachment protein do?

A

Interacts with the receptor on the host cell to allow entry

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

How come receptors cannot be eliminated to prevent infections?

A

These receptors are generally essential for the host cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

What is the cellular function of the CD4 receptor?

A

Immune cell interactions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What virus attaches to the CD4 receptor?

A

HIV (Retroviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is the cellular function of the ICAM-1 receptor?

A

Cell adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

Which virus attaches to the ICAM-1 receptor?

A

Rhinovirus (Picornaviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is the cellular function of the Bgp 1a receptor?

A

Cell adhesion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

Which virus attaches to the Bgp 1a receptor?

A

MHV-A59 (Coronaviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is the cellular function of the CR2 receptor?

A

B-cell activation

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Which virus attaches to the CR2 receptor?

A

Epstein-Barr virus (Herpesviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

What is the cellular function of the sialic acid receptor?

A

Various functions

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

Which viruses attaches to the sialic acid receptor?

A

Influenza virus (Orthomyxoviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What is the cellular function of the OmpF receptor?

A

Transmembrane channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

Which virus attaches to the OmpF receptor?

A

T2 (Myoviridae)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

What receptor does HIV (Retroviridae) bind to?

A

CD4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What receptor does Rhinovirus (Picornaviridae) bind to?

A

ICAM-1

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What receptor does MHV-A59 (Coronaviridae) bind to?

A

Bgp 1a

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What receptor does Epstein-Barr virus (Herpesviridae) bind to?

A

CR2

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

What receptor does Influenze virus (Orthomyxoviridae) bind to?

A

Sialic acid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

What receptor does T2 (Myoviridae) bind to?

A

OmpF

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What are bacteriophages?

A

Viruses that infect bacteria

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

What do most bacteriophages uses for attachment?

A

Tail fibers which recognize receptors present on the surface of bacterial cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

What 2 molecules does T2 recognize?

A

Lipopolysaccharide, and the outer membrane protein porin F precursor (OmpF)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What bacteria does T2 infect?

A

K-12 strain of E. coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What strain of E. coli can T2 not infect?

A

O157:H7 (pathogenic strain)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

What proteins are found at the tips of the T2 phage?

A

GP37 and GP38

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

How was it proven that T2 host range was due to strain specific differences in receptors?

A

The proteins on T2 tail fibers were replaced with proteins from a phage that could infect O157:H7 E. coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

What happened when the proteins on T2 tail fibers were replaced with proteins from a phage that could infect O157:H7 E. coli?

A

The T2 phage could not infect K-12 E. coli, but it could infect O157:H7 E. coli

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

How do enveloped viruses attach to host cells?

A

By a specific viral protein embedded within the envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What viral attachment protein is found in H1N1 influenza virus?

A

HA

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

What does HA stand for?

A

Hemagglutinin

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How does adenovirus attach to a host cell?

A

With a viral attachment protein that extends from the capsid

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

How does poliovirus attach to a host cell?

A

With a protein that is part of the capsid itself

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
37
Q

What do adenovirus and poliovirus have in common?

A

They are both non-enveloped viruses

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
38
Q

What virus have scientists used to study strain specificity?

A

MHV

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
39
Q

What does MHV stand for?

A

Mouse hepatitis virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
40
Q

What viruses are related to MHV?

A

SARS coronavirus and MERS coronavirus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
41
Q

How come two strains of mice showed different susceptibility to MHV?

A

They had different protein receptors

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
42
Q

Compare the Bgp 1a and Bgp 1b receptor.

A

The two proteins are structurally similar, but differ in amino acid sequences

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
43
Q

What is the consequence of the amino acid differences in the Bgp 1 receptor?

A

It changes the conformation, so MHV interacts more strongly with Bgp 1a than Bgp 1b

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
44
Q

What must happen after a virus binds to a host cell?

A

The virus or its genome must enter the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
45
Q

After an enveloped virus binds to a host cell, what separates the viral genome from the cell?

A

Two lipid bilayers (the viral envelope and the plasma membrane)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
46
Q

What interaction triggers receptor mediated endocytosis of influenza?

A

HA with sialic acid glycoprotein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
47
Q

What method does influenza use to enter the host cell?

A

Receptor mediated endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
48
Q

What causes the conformational change of HA?

A

Acidification of the viral envelope

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
49
Q

What happens when HA changes conformation?

A

It exposes a fusion peptide

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
50
Q

What does the fusion peptide do in influenza virus?

A

It helps the fusion of the viral envelope and the endosomal membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
51
Q

What happens when the viral envelope fuses with the endosomal membrane?

A

The nucleocapsid is released into the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
52
Q

How does HIV anchor to a host cell?

A

The attachment protein gp120 binds to the CD4 receptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
53
Q

What happens when gp120 binds to CD4?

A

There is a conformational change in gp120, allowing it to bind to the coreceptor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
54
Q

What happens when gp120 binds to the coreceptor?

A

This causes additional conformational changes, leading to the exposure of a fusion protein on gp41

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
55
Q

What is the purpose of gp41 in HIV?

A

It has the fusion protein that helps the fusion between the viral envelope and the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
56
Q

What was the first antiretroviral drug approved by the FDA, and when?

A

Fuzeon in 2003

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
57
Q

What does Fuzeon do?

A

It is designed to prevent entry of HIV by preventing fusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
58
Q

How does Fuzeon work?

A

It binds to gp41, preventing conformational change and fusion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
59
Q

What does entry for non-enveloped viruses require?

A

Direct penetration of cellular membrane by virus particle or genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
60
Q

Generally, how do non-enveloped viruses enter a cell?

A

Through receptor mediated endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
61
Q

How does receptor mediated endocytosis work?

A

Virus particles bind to the receptor on the cell surface, leading to endocytosis

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
62
Q

What happens when a non-enveloped virus enters a cell through receptor mediated endocytosis?

A

The low pH of the endosome causes a conformational change in the capsid (similar to influenza HA protein)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
63
Q

What happens when the capsid undergoes a conformational change in the endosome?

A

It exposes a pore forming domain that leads to the formation of a hole in the membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
64
Q

What is the purpose of the pore forming domain in a non-enveloped virus?

A

It allows the viral capsid or genetic material to enter the cytoplasm of the host cell from the endosome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
65
Q

What type of virus is reovirus?

A

A non-enveloped virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
66
Q

What part of a bacteriophage enters the host cell?

A

The genome (not the particle itself)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
67
Q

What happens when T4 binds to the receptor?

A

It leads to the contraction of the T4 tail

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
68
Q

What is the result of the T4 tail contracion?

A

The tail core pushes through the cell wall, bringing the phage DNA in contact with the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
69
Q

How does the phage DNA in T4 enter the cell?

A

Through the help of a pilot protein

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
70
Q

What does the pilot protein do?

A

It binds to the phage DNA, and helps it penetrate the plasma membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
71
Q

Where does the viral capsid go in a bacteriophage infection?

A

It remains outside the cell

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
72
Q

True or false: plant viruses, like bacteriophages, inject their genome into host cells

A

False: they do not inject their genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
73
Q

How do plant viruses enter cells?

A

They rely on the help of external forces, such as insects

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
74
Q

How do insects help plant viruses?

A
  1. Insects feed on plants, damaging the cuticle and cell wall
  2. When feeding, insects may acquire viruses, and transmit the particles
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
75
Q

How come plant viruses rely on external forces to enter cells?

A

Due to the tough cell wall

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
76
Q

What is tomato yellow leaf virus?

A

A plant virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
77
Q

For most mammalian viruses, what is needed to allow for the viral genome to interact with the required host cell machinery?

A

Some form of uncoating

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
78
Q

What is the first step of poliovirus uncoating?

A

After binding, the particles undergo a conformational change, resulting in the loss of capsid protein VP4

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
79
Q

What happens when poliovirus loses VP4?

A

VP1 can interact with the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
80
Q

What does VP1 do?

A

It creates a pore through the cell membrane

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
81
Q

How does the RNA in poliovirus get from the capsid to the cytoplasm?

A

It leaves the partially disassembled capsid through the VP1-induced channel

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
82
Q

How many different replication groups are there?

A

7

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
83
Q

How many DNA replication groups are there?

A

3 (dsDNA, ssDNA, dsDNA using RT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
84
Q

How many RNA replication groups are there?

A

4 (dsRNA, + ssRNA, - ssRNA, ssRNA using RT)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
85
Q

What is Baltimore classification based on?

A

How the mRNA of different viruses is produced

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
86
Q

What is a Class I virus?

A

dsDNA virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
87
Q

How do Class I viruses make mRNA?

A

By using dsDNA genome as a template

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
88
Q

Where does genome replication occur for Class I viruses?

A

Usually in the nucleus of host cells

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
89
Q

What is an exception to the genome replication rule for Class I viruses?

A

Pox (replicates in cytoplasm using viral enzymes)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
90
Q

How do Class I viruses replicate the genome?

A

Through host cell DNA-dependent DNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
91
Q

What is a Class II virus?

A

ssDNA virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
92
Q

How do Class II viruses make mRNA?

A

By using a dsDNA intermediate

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
93
Q

When does genome replication of Class II viruses occur?

A

As ssDNA gets converted into dsDNA, which serves as the template for more genomes

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
94
Q

What is a Class III virus?

A

dsRNA virus

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
95
Q

How do Class III viruses make mRNA?

A

From one strand (negative strand) of the ds genome

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
96
Q

Where does genome replication of Class III viruses occur?

A

In the cytoplasm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
97
Q

How do Class III viruses replicate the genome?

A

Through viral RNA-dependent RNA polymerase

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
98
Q

What is a Class IV virus?

A

ssRNA, positive sense

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
99
Q

How do Class IV viruses make mRNA?

A

The genome can be recognized by host ribosomes, and functions directly as mRNA

100
Q

Where does genome replication of Class IV viruses occur?

A

In the cytoplasm

101
Q

How do Class IV viruses replicate the genome?

A

Through viral RNA-dependent RNA polymerase

102
Q

What is a Class V virus?

A

ssRNA, negative sense

103
Q

How do Class V viruses make mRNA?

A

By using viral RNA-dependent RNA polymerase on the genome (serves as template for mRNA)

104
Q

How do Class V viruses replicate the genome?

A

Through viral RNA-dependent RNA polymerase

105
Q

Where does genome replication of Class V viruses occur?

A

In the cytoplasm

106
Q

What is a Class VI virus?

A

ssRNA, uses RT

107
Q

What type of enzyme is RT?

A

RNA dependent DNA polymerase

108
Q

How does a Class VI virus use RT?

A

It converts ssRNA genome into dsDNA, which becomes integrated into the host genome

109
Q

How do Class VI viruses make mRNA?

A

From the integrated dsDNA in the host genome

110
Q

How do Class VI viruses replicate the genome?

A

From the integrated dsDNA in the host genome (make more ssRNA)

111
Q

What is a Class VII virus?

A

dsDNA, uses RT

112
Q

How does a Class VII virus make mRNA?

A

From the dsDNA genome

113
Q

How do Class VII viruses replicate the genome?

A

By using RT on the mRNA

114
Q

How do Class VII viruses use RT?

A

By recreating genomic dsDNA from the mRNA

115
Q

What does the genetic material of DNA viruses resemble?

A

The genetic material of host cells

116
Q

Generally, where does replication of DNA viruses occur?

A

In the nucleus

117
Q

What do DNA viruses use to replicate the genome?

A

Host cell DNA polymerase

118
Q

What do DNA viruses use to produce mRNA molecules?

A

Host cell RNA polymerase

119
Q

What is an example of a typical DNA virus (that replicates in the nucleus)?

A

Papillomaviruses

120
Q

What are certain strains of papillomaviruses strongly associated with?

A

Cervical cancers

121
Q

What is an example of an atypical DNA virus?

A

Poxviruses

122
Q

Why is a poxvirus an atypical DNA virus?

A

It replicates in the cytoplasm, not the nucleus (like most DNA viruses)

123
Q

What type of virus is poxvirus?

A

Class I (dsDNA genome)

124
Q

What proteins do poxviruses bring with them when infecting a cell?

A

Viral RNA polymerase and several transcription factors

125
Q

How is poxvirus mRNA made?

A

From using the viral RNA polymerase in the cytoplasm

126
Q

What happens to the poxvirus mRNA?

A

It gets translated in the cytoplasm

127
Q

What is one key enzyme produced by poxvirus mRNA?

A

A viral DNA polymerase to replicate the genome

128
Q

How does poxvirus replicate its genome in the cytoplasm?

A

One gene it encodes for is a viral DNA polymerase, which replicates the genome

129
Q

What do early genes in poxvirus code for?

A

DNA polymerase and other proteins necessary for genome replication

130
Q

What do late genes in poxvirus code for?

A

Structural proteins needed for capsid and envelope formation

131
Q

In terms of the central dogma, what do cells usually do?

A

Make RNA from DNA

132
Q

In terms of the central dogma, what do cells not usually do?

A

Make RNA from RNA

133
Q

Which protein produces RNA from an RNA template?

A

RNA dependent RNA polymerase

134
Q

For RNA viruses, what does RNA dependent RNA polymerase do?

A

Makes genomic RNA, and mRNA that can be recognized and translated by host ribosomes

135
Q

Where does replication of RNA viruses usually occur?

A

In the cytoplasm

136
Q

What is a retrovirus?

A

A virus that uses RT (Class VI and Class VII)

137
Q

What class of virus is poliovirus?

A

Class IV (+ ssRNA)

138
Q

Where do Class IV viruses get RNA polymerase?

A

It is translated directly from the ssRNA genome

139
Q

True or false: Class IV viruses need to bring RNA polymerase into the cell

A

False: it can be transcribed directly from the + sense ssRNA genome

140
Q

What happens if the poliovirus genome is artificially injected into the host cell?

A

It will still cause the same infection

141
Q

How come injecting the poliovirus genome directly into a host cell will cause the same infection?

A

It is a + sense ssRNA genome, so it can be used directly by the cell

142
Q

What is another name for viral + sense ssRNA?

A

Infectious RNA

143
Q

What is - sense ssRNA used for?

A

A template for the complementary + sense ssRNA (which can be read by the host cell ribosomes)

144
Q

Where do Class V viruses get RNA polymerase?

A

They bring it with them

145
Q

True or false: Class V viruses need to bring RNA polymerase into the cell

A

True: they need it to create the + sense ssRNA from the - sense ssRNA genome

146
Q

What does the ssRNA genome of retroviruses produce?

A

RT

147
Q

What does RT do once an RNA retroviruses enters the cell?

A

It uses the RNA as a template to make a DNA-RNA heteroduplex

148
Q

What happens after RT makes the DNA-RNA heteroduplex?

A

It degrades the original RNA molecule with endonuclease activity, and converts the ssDNA into dsDNA

149
Q

What is the endonuclease activity of RT?

A

RNAse H

150
Q

What happens after RT makes dsDNA?

A

The dsDNA moves to the nucleus, where it is integrated into the genome

151
Q

How is dsDNA integrated into the genome (for retroviruses)?

A

Through the viral enzyme integrase

152
Q

What does integrase do?

A

Integrates viral dsDNA into the host cell genome

153
Q

What is the integrated viral DNA known as?

A

Provirus or proviral DNA

154
Q

What happens once the dsDNA is integrated into the genome?

A

The host cell RNA polymerase transcribes the integrated viral genome, producing mRNA

155
Q

What happens when the full length genomic RNA molecules leave the nucleus (in Class VI viruses)?

A

The viral mRNA is translated in the cytoplasm to produce viral proteins and new viral RNA genomes

156
Q

What can the genome of a bacteriophage be?

A

DNA or RNA

157
Q

How do DNA bacteriophages make new genomic copies?

A

Through the host cell DNA polymerase

158
Q

How do RNA bacteriophages make new genomic copies?

A

By using viral RNA polymerase

159
Q

What type of genome do most RNA bacteriophages have?

A

+ sense RNA genome

160
Q

What do lytic phages do?

A

They replicate and lyse the host cell

161
Q

What is another name for lytic phages?

A

Virulent phages

162
Q

What do temperate phages do?

A

They either insert their genome into host cells, or enter the lytic phase

163
Q

How does the genome of P1 of E. coli exist?

A

As a plasmid in the cytoplasm

164
Q

What type of virus is P1?

A

A temperate phage

165
Q

What does the cell do when it has an integrated viral genome?

A

It continues to replicate the viral genome without production of viral particles

166
Q

What can lambda phage do in E. coli to replicate?

A

It can either lyse the cell, or integrate the genome into the genome of the host cell, and replicate with the host DNA

167
Q

What is a prophage?

A

The quiescent viral genome that exists as either a plasmid or integrated into the host genome

168
Q

What is a lysogen?

A

A cell containing a prophage

169
Q

What happens when linear lambda phage DNA enters the cell?

A

It becomes circular

170
Q

What does circular lambda phage DNA do?

A

It integrates into the viral genome (via integrase enzyme)

171
Q

What is c1 and what does it do?

A

Viral repressor protein that represses cro genes

172
Q

What is cro and what does it do?

A

Repressive protein required for lytic replication

173
Q

What happens if there are high amounts of c1?

A

cro is repressed, and lysogenic phase is maintained

174
Q

How can c1 levels drop in a cell?

A

In response to damage causes by UV light or chemical mutagens

175
Q

What happens when c1 levels drop?

A

The cro protein represses the c1 protein needed to maintain the lysogenic phase

176
Q

What happens if there are high amounts of cro?

A

The proteins for lytic replication are produced, maintaining lytic replication

177
Q

How can lambda phage switch between lytic and lysogenic replication?

A

Based on the relative ratio of the two repressor proteins c1 and cro

178
Q

How do cro and c1 levels change in the cell?

A

In response to the overall health of the cell

179
Q

What does c1 bind to?

A

The cro promoter

180
Q

What does cro bind to?

A

The c1 promoter

181
Q

What happens after a virus makes copies of the viral genome and proteins?

A

New viral particles must assemble and leave the infected cell

182
Q

For assembly, what are many viral components?

A

Self assembling

183
Q

What is the advantage of self assembly?

A

From an energetic perspective, it is fast and cheap

184
Q

How do viral proteins assemble?

A

Around the viral nucleic acid, or inserted into an empty capsid

185
Q

How does TMV assemble?

A

The viral proteins assemble around the viral nucleic acid

186
Q

What must a viral genome have to allow viral proteins to assemble around it?

A

A sequence specific assembly motif

187
Q

What is another name for the sequence specific assembly motif?

A

The packaging sequence

188
Q

How does poliovirus assemble?

A

An empty capsid is partially assembled, and the genome is inserted

189
Q

What does the mechanism of egress depend on?

A

The virus type and host cell type

190
Q

What are the steps for egress of enveloped viruses?

A
  1. Viral proteins are inserted into the host cell membrane
  2. Nucleocapsid migrates to membrane with viral proteins
  3. Budding of nucleocapsid
191
Q

What does budding of the nucleocapsid result in?

A

A lipid bilayer containing enveloped proteins

192
Q

What does the envelope of HIV contain?

A

gp120 and gp41 proteins

193
Q

How do non-enveloped viruses egress?

A

Through lysis of the cell

194
Q

How do bacteriophages egress?

A

They produce specific enzymes to destroy the cell membrane and cell wall

195
Q

How do non-enveloped mammalian viruses egress?

A

The cell becomes unstable due to viral replication (no specific enzymes required)

196
Q

True or false: plant viruses lyse the host cell

A

False: they do not lyse the host cell

197
Q

How do plant viruses egress?

A

They travel from one cell to another through cytoplasmic connections

198
Q

How can plant viruses spread from one plant to another?

A

Through disruption of the cell wall structures by outside forces (insects)

199
Q

How do viruses move towards cells?

A

Via simple diffusion

200
Q

What is E. coli strain O157:H7 associated with?

A

Severe intestinal disorders in humans

201
Q

What is T2ppD1?

A

The altered T2 phage with different tail fiber proteins (to test host range)

202
Q

What did scientists use to study strain susceptibility to MHV?

A

SDS page of the two different receptors

203
Q

How do antibodies block viral infections?

A

They bind to viruses to block the interaction between virus and host cell to prevent attachment

204
Q

What is Maraviroc used to treat?

A

HIV

205
Q

What is another name for Maraviroc?

A

Selzentry

206
Q

How does Maraviroc work?

A

It blocks the interaction between the viral attachment protein and the CCR5 co-receptor by binding to CCR5

207
Q

What types of patients is Maraviroc used for?

A

People already with the virus (to slow down progression) (not for prevention)

208
Q

What type of HIV is Maraviroc ineffective against?

A

Strains of HIV that use CXCR4 co-receptor

209
Q

How does HIV enter the cell?

A

It fuses directly with the envelope (no endosome)

210
Q

What is the structure of the fusion peptide?

A

A short string of hydrophobic amino acids

211
Q

What is meant by a virus being pH-dependent?

A

It relies of the low pH of the endosome to function

212
Q

What is a cuticle?

A

A thick waxy cover to protect the plants

213
Q

What are plasmodesmata?

A

Cytoplasmic connections between plant cells

214
Q

Which types of viruses generally require uncoating?

A

Mammalian viruses

215
Q

Which types of viruses do not require uncoating?

A

Bacteriophages

216
Q

What does PVR stand for?

A

Poliovirus receptor

217
Q

What receptor does poliovirus bind to?

A

PVR

218
Q

What happens when poliovirus binds to PVR?

A

The 160S particle becomes a 135S particle

219
Q

What happens when poliovirus becomes a 135S particle?

A

Lipophilic portions of VP1 and VP4 are exposed

220
Q

Which factors do not inhibit poliovirus replication?

A

Blocking endocytosis, and blocking endosome acidification

221
Q

How does poliovirus RNA likely enter the cell?

A

Through either the plasma membrane or the endosomal membrane

222
Q

What is the result of measuring the kinetics of viral replication?

A

A one-step multiplication curve

223
Q

What can be determined from a one-step multiplication curve?

A

The burst size (average number of progeny viruses released from one cell)

224
Q

What family is SV40 a part of?

A

Polyomaviridae family

225
Q

What is the genome is SV40?

A

Small circular DNA genome

226
Q

What viral proteins unwinds the viral genome for SV40?

A

Large T antigen

227
Q

What happens after the viral genome of SV40 is unwound?

A

Host cell primases and DNA polymerases replicate the genome

228
Q

How does large T antigen facilitate viral replication?

A

By priming the cell towards DNA synthesis

229
Q

How does large T antigen prime the cell towards DNA synthesis?

A

By interacting with cell cycle regulatory proteins

230
Q

What can viruses facilitating DNA synthesis lead to?

A

Immortal cell lines

231
Q

Besides SV40, what other virus can drive the cell towards DNA synthesis?

A

HPVs (Human Papillomaviruses)

232
Q

For polyomaviruses and papillomaviruses, what is responsible for transcription of the viral genes?

A

The host cell RNA polymerase II

233
Q

What happens if + sense RNA is converted into a DNA plasmid?

A

The plasmid becomes infectious

234
Q

What is the purpose of making an infectious plasmid from + sense RNA?

A

Researchers can mutate the plasmid (representing the viral genome), and observe the effect on cells

235
Q

What does HIV cause?

A

AIDS

236
Q

Why were retroviruses initially studied?

A

Their ability to form tumors

237
Q

Who studied the first retrovirus?

A

Peyton Rous in 1911

238
Q

What is the most famous retrovirus?

A

HIV

239
Q

How does HIV assemble?

A

It forms a non-infectious precursor, which is then proteolytically processed to a mature, infectious particle

240
Q

How do protease inhibitor drugs work as antivirals?

A

They block proteolytic processing for proper HIV assembly

241
Q

What is the initial precursor capsid of poliovirus made out of?

A

VP1, VP3, and VP0

242
Q

How is poliovirus processed to become a mature virion?

A

VP0 is cleaved into VP2 and VP4

243
Q

What is the advantage of a segmented genome?

A

It allows for genetic variability

244
Q

What virus has a segmented genome?

A

Influenza (8 - ssRNA)

245
Q

How is the nucleocapsid brought in contact with the membrane for egress?

A

Interactions with amino acids of the tail region with the nucleocapsid

246
Q

What enzyme does T4 make for egress?

A

Lysozyme (break down cell wall)

BIO 315 (12 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions