Lecture Exam #4 Flashcards
Lectures 17 - (184 cards)
1
Q
4 traits of viruses
A
- extremely small
- acellular
- Obligate Intracellular Parasites
- Don’t perform any metabolic functions outside cell
2
Q
what do viruses consist of
A
nucleic acids and proteins
3
Q
Viruses (do/don’t) require a host cell to replicate
A
do require
4
Q
Viral structure (3)
A
nucleic acid core
capsid
envelope (sometimes)
5
Q
nucleic acid core of virus description
A
DNA or RNA
single or double stranded
6
Q
capsid definition
A
protein coat surrounding nucleic acid core
7
Q
capsid functions
A
protection
attachment
8
Q
capsid structure
A
capsomeres
all capsomeres together = capsid
9
Q
capsomere definition
A
individual protein subunits
10
Q
viral envelope definition
A
only in some viruses
surrounds the capsid
11
Q
what is the viral envelope derived from
A
derived from host cell’s membrane
12
Q
composition of viral envelope
A
mainly lipids + proteins and carbohydrates
may be covered with spikes
13
Q
what are the possible spikes in the viral envelope made of/its purpose
A
glycoproteins that project from envelope
help virus to attach to host cell
14
Q
virion definition
A
complete, fully developed, infectious viral protein
15
Q
host range definition
A
spectrum of cells a virus can infect
16
Q
how are viral proteins and host receptors binded together
A
complementary binding
16
Q
host range is determined by
A
interaction between viral proteins and receptors on host cell
17
Q
steps in animal virus infection
A
1) Attachment
2) Entry
3) Uncoating
4) Biosynthesis
5) Maturation
6) Release
18
Q
where does attachment occur in animal virus infection
A
occurs between proteins on viruses and receptors on host cell
19
Q
What is attachment like in enveloped viruses
A
proteins on envelope that attach to cellular receptors
20
Q
what is attachment like in non-enveloped viruses
A
capsid proteins attach to cellular receptors
21
Q
what occurs during entry in animal virus infection
A
crossing cell’s plasma membrane
22
Q
methods of entry in animal virus infection
A
receptor-mediated fusion
receptor-mediated endocytosis
23
Q
receptor-mediated fusion is used by ___
A
used by enveloped viruses only
24
receptor-mediated fusion step 1
protein on enveloped virus binds to receptor on host cell
25
receptor-mediated fusion step 2
viral envelope fuses with cell's plasma membrane
26
receptor-mediated fusion step 3
capsid + nucleic acids released into cell's cytoplasm
27
receptor-mediated endocytosis is used by ___
used by enveloped and non-enveloped viruses
28
receptor-mediated endocytosis step 1
virus binds to receptor on host cell
29
receptor-mediated endocytosis step 2
host cell's plasma membrane folds in
30
receptor-mediated endocytosis step 3
virus enters cell
31
step 1 of uncoating in animal virus infection
viral nucleic acids and capsid separate
32
step 2 of uncoating in animal virus infection
capsid degraded by host lysosomal enzymes or acidification
33
how is capsid degraded in uncoating (2)
host lysosomal enzymes
acidification
34
step 3 of uncoating in animal virus infection
viral nucleic acids travel to replication site
35
what is the eclipse phase of uncoating in animal virus infection
infectious particles are undetectible
36
infectious particles are/aren't detectible during uncoating phase of animal virus infection
aren't detectible
37
what does biosynthesis in animal virus infection include (3)
nucleic acid replication
transcription of viral mRNA
translation of viral proteins
38
is biosynthesis the same for every virus?
no - differs between DNA viruses, RNA viruses, and retroviruses
39
1st step of Biosynthesis of DNA viruses
viral DNA replicated -> more viral DNA
40
enzyme used in 1st step of Biosynthesis of DNA viruses
DNA polymerase (from host cell)
41
cellular location in 1st step of Biosynthesis of DNA viruses
nucleus
42
2nd step of Biosynthesis of DNA viruses
viral DNA trancribed -> viral mRNA
43
enzyme used in 2nd step of Biosynthesis of DNA viruses
RNA polymerase (from host cell)
44
cellular location in 2nd step of Biosynthesis of DNA viruses
nucleus
45
3rd step of Biosynthesis of DNA viruses
viral mRNA translation -> viral proteins
46
cellular location in 3rd step of Biosynthesis of DNA viruses
ribosomes
47
1st step of Biosynthesis of RNA viruses
viral RNA replicated -> more viral RNA
48
enzyme used in 1st step of Biosynthesis of RNA viruses
RNA-dependent RNA polymerase (viral enzyme)
49
RNA-dependent RNA polymerase function
use RNA as template to make more RNA (different from RNA polymerase)
50
cellular location in 1st step of Biosynthesis of RNA viruses
cytoplasm
51
what senses can viral RNA be
+ sense
- sense
52
+ sense viral RNA definition
functions are mRNA (can be translated immediately)
53
- sense viral RNA definition
does not function as mRNA (can't be translated immediately)
54
biosynthesis of + sense RNA viruses
+ sense RNA functions are mRNA -> translated into viral protiens
55
cellular location of biosynthesis of + sense RNA viruses
ribosomes
56
step 1 in biosynthesis of - sense RNA viruses
- sense RNA does not function as mRNA -> must be replicated into + sense RNA
57
enzyme used in step 1 in biosynthesis of - sense RNA viruses
RNA-dependent RNA polymerase
58
cellular location of step 1 in biosynthesis of - sense RNA viruses
cytoplasm
59
step 2 in biosynthesis of - sense RNA viruses
+ sense RNA can be translated into viral proteins
60
cellular location of step 2 in biosynthesis of - sense RNA viruses
ribosomes
61
retroviruses definition
RNA viruses
62
step 1 of biosynthesis of retroviruses
viral RNA reverse transcribed -> viral DNA
63
enzyme used in step 1 of biosynthesis of retroviruses
reverse transcriptase
64
cellular location of step 1 of biosynthesis of retroviruses
cytoplasm
65
step 2 of biosynthesis of retroviruses
viral DNA migrates to nucleus and is integrated into host cell's chromosome/genome -> provirus
66
provirus definition
viral DNA integrated into host cell's chromosome/genome
67
2 possibilities of what can happen to a provirus
provirus remains latent
provirus is expressed
68
what happens when provirus remains latent
replicates when host cell chromosome replicates -> viral proteins not synthesized
69
what happens when provirus is expressed
viral proteins synthesized
70
what occurs in maturation in animal virus infection
viral nucleic acids put inside capsids -> virions
71
what occurs in release in animal virus infection
viruses are released from host cell
72
methods of release in animal virus infection
budding
rupture
73
budding release in animal virus infection is used by ___
enveloped viruses
74
rupture release in animal virus infection is used by ___
non-enveloped viruses
75
step 1 of budding release in animal virus infection
capsid containing nucleic acids pushes through plasma membrane
76
step 2 of budding release in animal virus infection
part of plasma membrane sticks to capsid
-> becomes envelope
77
step 3 of budding release in animal virus infection
enveloped virus released
78
the host does/does not survive in budding release in animal virus infection
the host does survive
79
step 1 of rupture release in animal virus infection
viruses rupture plasma membrane
80
step 2 of rupture release in animal virus infection
non-enveloped viruses released from host cell
81
the host does/does not survive in rupture release in animal virus infection
host does not survive
82
why are antiviral drugs used to attack viruses
difficult to attack viruses without damaging host cells
83
can antibiotics attack a virus
no - never use antibiotics to treat a viral infection
84
antiviral drugs function
antiviral drugs can inhibit any step during virus infection
85
inhibitors of nucleic acid synthesis
nucleic acid analongs
86
nucleic acid analogs look like what
nucleic acids
87
nucleic acid analogs function
inhibit nucleic acid synthesis once incorporated
88
2 examples of nucleic acid analogs
Acyclovir
Valacyclovir
89
function of acyclovir and valacyclovir specifically
inhibit Herpes Virus-specific DNA polymerase
90
Herpes Virus family includes ___ (2)
Herpes Simplex Viruses
Varicella Zoster Virus
91
interferons definition
immune response to viral infections
92
what do cells infected by viruses produce (2)
alpha-interferon
beta-interferon
93
what does alpha-interferon treat
viral hepatitis
94
Examples of DNA virus
Herpes Simplex Virus
95
Herpes Simplex Virus is (enveloped/non-enveloped)
enveloped
96
Herpes Simplex Virus types (2)
HSV-1
HSV-2
97
where does HSV-1 prefer to be
in oral mucosa
98
what does HSV-1 cause
Oral Herpes (most commonly)
Genital Herpes (most rarely)
99
signs/symptoms of oral herpes
cold sores
100
cold sores definition
painful, short-lived vesicles on outer margin of lips
101
HSV-1 transmission
oral secretions
102
HSV-1 Pathogenesis
- infects cells around site of entry (oral mucosa)
- remains latent in trigeminal nerve ganglia
- can travel back to oral mucosa -> active infection
103
where does HSV-1 remain latent
trigeminal nerve ganglia
104
HSV-1 activation is associated with (3)
UV light
Emotional stress
Menstruation
105
where does HSV2 prefer to be
genital mucosa
106
what does HSV2 cause
genital herpes (most commonly)
oral herpes (more rarely)
107
genital herpes signs/symptoms
vesicles on genitals
burning during urination
108
HSV2 transmission
sexual contact
109
HSV2 pathogenesis
- infects cells around site of entry (genital mucosa)
- remains latent in sacral nerve ganglia
- can travel back to genital mucosa -> active infection
110
where does HSV2 remain latent
sacral nerve ganglia
111
HSV2 activation is associated with ___ (2)
emotional stress
menstruation
112
example of an RNA virus
Rabies Virus
113
Rabies Virus is (enveloped/non-enveloped)
enveloped
114
what does Rabies Virus cause?
rabies
115
4 initial signs/symptoms of rabies
tingling around bite
muscle spasms
weakness
fever
116
2 possible forms of clinical rabies
furious rabies
paralytic rabies
117
signs/symptoms of furious rabies (4)
hydrophobia
excessive salivation
aggression
viral encephalitis
118
signs/symptoms of paralytic rabies (3)
muscle paralysis
viral encephalitis
coma
119
rabies virus transmission
saliva from bite of infected animal
120
most common reserviors of rabies virus
raccoons
skunks
bats
121
rabies virus pathogenesis
- rabies virus injected into body -> enter muscle cells and replicate
- rabies virus enters motor neuron and travels to CNS -> brain
- rabies virus can travel to salivary glands and other organs
122
retrovirus example
Human Immunodeficiancy Virus (HIV)
123
Cancer definition
abnormal cells divide uncontrollably
124
oncogene definition
gene with ability to convert normal cell to cancer cell
125
cancer is caused by ___ (3)
mutagens
viruses
inherited
126
oncogenic viruses definition
viruses that contain oncogenes
127
example of oncogenic virus
Human Papillomavirus (HPV)
128
how many types of HPV are there
over 200 types
129
what kind of virus is HPV
DNA virus
130
HPV is (enveloped/non-enveloped)
non-enveloped
131
what can HPV cause (2)
genital warts
cancer
132
2 most common HPV strains for genital warts
HPV-6
HPV-11
133
2 most common HPV strains for cancer
HPV-16
HPV-18
134
genital warts signs/symptoms
bumps on genitals
135
what kinds of cancer does HPV cause
anal and cervical cancer
136
HPV transmission
sexual contact
137
Pathogenesis of HPV (general - 1)
infects epithelial cells
138
pathogenesis of HPV-6 and HPV-11
- DNA remains extrachromosomal
- infected cells increased keratin production
139
pathogenesis of HPV-16 and HPV-18
- DNA integrates into host cell's chromosome
- HPV-16 and HPV-18 DNA encode proteins that suppress host cell tumor suppressor proteins
140
what does HPV vaccine protect against (2)
- cancer causing HPV (incl. 16/18)
- genital wart causing HPV (incl. 6/11)
141
bacteriophages definition
viruses that infect bacteria
142
2 life cycles of bacteriophages
lytic
lysogenic
143
Lytic life cycle definition
lysis and cell death
144
example of lytic bacteriophage
T-even Lytic Bacteriophage
145
Structure of T-even Lytic Bacteriophage
DNA core
Capsid
Sheath
Tail fibers
146
bacteriophage capsid function
surrounds DNA
147
bacteriophage sheath function
surrounds phage core
148
bacteriophage tail fibers function
attach to receptors on host cell
149
steps in life cycle of T-even Lytic Bacteriophage
1) attachment
2) penetration
3) biosynthesis
4) maturation
5) release
150
what occurs during attachment in life cycle of T-even Lytic Bacteriophage
tail fibers on bacteriophage attach to receptors on bacterial cell
151
what occurs during part 1 of penetration in life cycle of T-even Lytic Bacteriophage
lysosome is released to degrade bacterial cell wall
152
what occurs during part 2 of penetration in life cycle of T-even Lytic Bacteriophage
phage sheath contracts -> phage core punctures bacterial cell wall and injects DNA inside cell
153
what occurs during part 1 of biosynthesis in life cycle of T-even Lytic Bacteriophage
bacterial cell's nucleus and enzymes used to replicate bacteriophage DNA -> more bacteriophage DNA
154
what occurs during part 2 of biosynthesis in life cycle of T-even Lytic Bacteriophage
bacteriophage DNA transcribed -> bacteriophage mRNA
155
what occurs during part 3 of biosynthesis in life cycle of T-even Lytic Bacteriophage
bacteriophage mRNA translated -> bacteriophage proteins
156
what occurs during maturation in life cycle of T-even Lytic Bacteriophage
bacteriophages are assembled
157
what occurs during release in life cycle of T-even Lytic Bacteriophage
bacteriophages released from cell
158
how does release occur in life of T-even Lytic Bacteriophage
lysosome breaks down bacterial cell wall -> lysis -> bacteriophages exit and infect new cells
159
Lysogenic life cycle definition
cell remains alive
160
what occurs during Lysogenic life cycle
lysogenic bacteriophages incorporate their DNA into host cell's DNA
Bacteriophage DNA replicated every time host cell divides
161
property of Lysogenic life cycle
can convert to lytic cycle
162
example of Lysogenic bacteriophage
Lambda Lysogenic Bacteriophage
163
what occurs during attachment in life cycle of Lambda Lysogenic Bacteriophage
tail fibers on bacteriophage attach to receptors on bacterial cell
164
what occurs during penetration in life cycle of Lambda Lysogenic Bacteriophage
bacteriophage DNA injected into host cell
165
what occurs during the 3rd step in life cycle of Lambda Lysogenic Bacteriophage and what is created
bacteriophage DNA integrates into host's chromosome
inserted bacteriophage DNA = prophage
prophage genes not produced
166
what occurs during the 4th step in life cycle of Lambda Lysogenic Bacteriophag
prophage DNA replicated every time bacterial chromosome replicates
167
what occurs during the 5th step in life cycle of Lambda Lysogenic Bacteriophag
prophage can excise from bacterial chromosome -> lytic cycle -> released from host cell
168
prions definition
infectious proteins
169
who do prions infect
humans
animals
170
what do prions cause in humans and animals
transmissible spongiform encephalopathies (TSEs)
171
Prions are resistant to ___ (4)
heat (includes autoclave)
radiation
enzymes that digest DNA/RNA
protein-denaturing agents
172
2 prion conformations
PrPC
PrPSc
173
PrPC definition
cellular form found in tissues of healthy people/animals
174
PrPC relation to denaturing agents
sensitive
175
PrPSc definition
scrapie protein
176
PrPSc form
harmful form
177
PrPSc relation to denaturing agents
resistant
178
what do prion diseases cause
PrPC -> PrPSc
179
How do PrPSc attack the body
accumulate in brain and cause plaques
180
4 traits of prion diseases
- long incubation periods
- cause spongiform degeneration in brain
- progress rapidly
- always fatal
181
example of prion disease
Kuru
182
what does Kuru cause
cannibalism
(brain contains prion)
183
3 Kuru Signs/symptoms
- trembling
- depression/uncontrollable laughter
- lose ability to walk, swallow, and sleep
