Module 5 Flashcards
What was the first virus identified
Tobacco mosaic disease
What is a virus
Genetic element encapsulated in a protein shell
Can DNA and RNA be in the same virus
No
What is on a naked virus
Just protein
What is on an eveloped virus?
Lipids
Why aren’t viruses alive?
They don’t have independent metabolism
Why does a virus need a host?
Energy and protein synthesis
What does a virus need for energy and protein synthesis
Host
What is the extracellular form of a virus called?
Virion
Do viruses affect all life forms?
Yes
What microscopy would be used to view a virus?
Transmission electron microscopy because it is very small
What kind of microscope cannot be used to see a virus?
Light microscope
The Larger the genome, the what?
More protein they’ll have
What is a capsid made of?
Protein subunit(s) called capsomeres
How does a capsid assemble?
Either self assembly or requires the host
What is a genome
DNA or RNA → 1 or more fragment
What are the 2 primary shapes of a virion?
Rod → helical symmetry
Spherical → icosahedral symmetry
Which primary shape requires more protein? Why?
Icosahedral → to make a more complex capsid
What’s the simplest and most effective arrangement. Why?
Icosahedral symmetry → fewer capsomeres are required
How many protein does helical symmetry require
Only 1 so it is not as complex as icosahedral
What’s an example of a complex shape?
Icosahedral heal + helical tail
What is a complex shape?
Non symmetrical
What is the structure of a naked virus?
Capsid + nucleic acid
What is the structure of an enveloped virus
Membrane
Capsid
Nucleic acid
Where does the phospholipid belayer come from?
Host
What are fibrils
Peptidoglycan like polymers on amoeba viruses
What are glycoprotein spikes for?
Interaction with hosts
What is a spike protein?
Protein on the surface of viruses
Are there other things than just nucleic acid within a virion
Yes → can be enzymes
Why arent viruses a part of the tree of life
They have no rna → can’t classify them
What is the difference between a virus and a disease
Disease shows symptoms → virus is what you have
How do we classify viruses? (4)
Fast evolution (families and genera)
Nucleic acid type and how it replicates
Naked or enveloped
Baltimore classification
What does the Baltimore classification demonstrate?
Nuclei’s acid type and replication
What does the Baltimore classification demonstrate?
Nuclei’s acid type and replication
How many groups of Baltimore classification are there?
7 groups
How do pages infect bacteria? (5)
- Attachment
- penetration
- Biosynthesis
- Maturation
- Lysis
Why do licit viruses exhibit a one step growth curve?
Lyric viruses are only released all at once
How do phages infect bacteria?
Receptors
What are the unique receptors of gram positive bacteria?
Cell wall, LTA, WTA
What are the unique receptors of gram negative bacteria?
Pili
Porin
LPS
CPS
EPS
What receptor do both gram negative and gram positive have?
Flagellum
How do temperate phases infect bacteria
They go through a Lysogenic and lytic life cycle
How do temperate phases infect bacteria
They go through a Lysogenic and lytic life cycle
What is a lysogen
A bacterium that has the temperate phages bacteria integrated into its bacterial genome
What is Lysogenic or phage conversion?
The new phage changes the phenotype Of the lysogen
What happens if there is no phage
No disease
What is the lysogenic cycle
A phage integrating its genome into a bacterial chromosome
Where does the Baltimore classification come in?
During biosynthesis in eukaryotic cells
What does penetration look like for eukaryotic cells and naked viruses
Endocytosis
What does penetration look like for eukaryotic cells and enveloped viruses
Membrane fusion
What is tissue tropism
The preferences of a virus to infect specific types of tissues or cells within a host organism
How does a naked virus release mature viruses
Lysis that will destroy host cells and cause tissue damage
How does an enveloped virus release mature viruses
Buds out through host membrane and host cell may survive
Which form of virus has continued slow release (potentially for life)
Enveloped viruses
What is a latent virus
A virus that is dormant and reactivates
What is a chronic virus?
Not eliminated and there is a continuous production of viral particles
What are the 3 outcomes for viral infections
Latent
Chronic
Cancer
What does a virus need to grow
Host cells
What is formed after the lysis of a host cell
A plaque
Does a lysogenic infection always result in lysis?
No
What’s unique about the central dogma for viruses?
DNA or RNA can be a starting point
Can viruses replicate both DNA and RNA?
Yes
when are plaques formed
during lysis
viral infection steps in order (6)
attachment
penetration
uncoating
biosyntheses
assembly
release
what is a prophage
bacteriophage that is integrated in a bacterial chromosome
what is a virulent phage
bacteriophage that displays a lytic life cycle
