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What 3 structures are viruses made out of? NCE
- nucleic acid
- capsid
- +/- envelope
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Can a virus be made of both DNA and RNA?
NO! It has to be one or the other. Never both.
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What is the protein shell/coat?
the capsid
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What is the envelope made of?
a monolayer of lipids
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What is a non-enveloped virus called?
naked
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Viruses are obligate _ parasites.
intracellular
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Viruses depend on _ _ _ _ for their reproduction and are NOT free living.
the host cell metabolism
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List several vectors for viruses used in science: MTE
- mice
- tissue culture
- embryonated chicken egg
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What are the 3 variations in size?
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What is an example for a large virus?
poxvirus
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What is a example of a small virus?
parvovirus
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What are prions?
"virus like" proteins
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Do prions have nucleic acids?
no they are only "virus like"
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What do prions typically form?
spongiformes
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What type of diseases do prions cause? Name an example.
- neurologic
- mad cow disease
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How are prions spread?
ingestion
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What 3 things are viruses classified on? SCE
- shape(as seen on an electron microscope)
- composition(of nucleic acid core/genome)
- Envelope(+/)
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Name that shape
helical
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Name that shape
isohedral
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Name that shape
bacteriophage
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How is the envelope produced?
by "budding" through the host cell membranes
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What is on the surface of an envelope?
glycoproteins
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What are the 3 uses of the glycoproteins on the surface of an envelope? IFA
- ID and bind to receptors of the host's membrane
- Fuse to host cell membrane
- Allow capsid and genome to enter and cause infection inside of host
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List 3 enveloped viruses: IHR
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Why do enveloped viruses cause persistant infections?
they can adapt and change
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Are enveloped viruses easy to kill?
yes
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How can you tell that a virus is naked?
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Are naked viruses easy to kill?
no
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Name two ways to kill naked viruses:SV
- steam sterilization
- viricidal compounds
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What settings is the autoclave at to kill naked viruses?temp,psi,time
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What are the 4 stages of replication?A,P/U,R/S,A/R
- attachment
- penetration/uncoating
- replication/synthesis
- assembly/release
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Name the step: Virus binds to cell
attachment
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Name 3 common methods of entry: RUG
Which is the top way?**
- Respiratory tract**
- Urogenital tract
- GI tract
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Name the step:
Entry of the virus genome into the host cell
Most viruses produce enzymes to degrade the host cell membrane
Nucleic acid core enters host cell
The capsid remains on the host cell exterior
Penetration/Uncoating
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Name the step:
Virus replicates to ensure survival
Viral nucleic acids take over host DNA
Host produces viral components
Host cell membrane breaks down
Immune response is initated but unable to respond
Prodromal period
Replication/Synthesis
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What is the prodromal period?
time before clinical signs and symptoms appear
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What are the two cycles that viruses go through?
Which is more common?**
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Name the cycle:
Viral DNA destroys cell DNA, takes over cell functions and destroys the cell
The virus replicates and produces progeny
There are symptoms of viral infection
Virulent infection takes place
lytic
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Name the cycle:
Viral DNA merges with Cell DNA and doesn't destroy the cell
The virus doesn't produce progeny
No symptoms of infection
Temperate infection takes place
lysogenic
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Name the step:
Concentration of viral components
Produce virions
Almost immediately leave cell
If cell is destroyed causes signs of disease
Move to neighboring cells to start over
Some shed in secretions
Some circulate
assembly/release
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What is VIREMIA?!
circulating viruses in blood
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