Virus Classification Flashcards
how is a virus different from a bacterium
Virus can NOT replicate w/out a host
-bacteria replicate autonomously
how is a virus different from a toxin
Virus CAN replicate inside a host
-toxin can not replicate
what is a bacteriophage
it is a virus that attacks then replicates inside a bacteria
T/F Bacteria are smaller than viruses ?
F - virus are smaller from 18-300 um
What are the two theories of Virus Origin
- Cellular origin - viruses were once cellular components and evolved separate over time
- Autopoietic Origin - viruses were originally their own independent entities and evolved to become dependent on other cells for replication
What are the 5 ways to classify a virus
- virus particle structure (main)
- genome (main)
- replication features (main)
- serology
- stability
using virus particle structure to classify a virus takes into account what 3 characteristics
- composition
- size
- shape
what is a nucleocapsid
RNA or DNA core protected by a capsid
what is a capsid
a virus’ protein coat
a virus is defined by its ______ structure
nucleoplasmid
nucleocapsids are composed of individual repeating protein subunits called ?
capsomeres
A virus particle structure may have envelopes, what are they ?
its a virus-modified cellular membrane
what are some disadvantages of an envelope
very susceptible to many lab solvents
what are the different types of genomes that a virus can have that help to classify viruses
DNA - single or double
RNA - single or double
—-(+) sense ssRNA
—–(-) sense ssRNA
what is the difference b/w (+) sense ssRNA and (-)sense ssRNA
(+)sense ssPNA is ready to be used to make proteins whereas (-)sense ssRNA must transcribe first
in order for replication to start in ssDNA, what specific structure must be formed
ssDNA hairpin
in order for replication of dsDNA to start, what structure must be formed
dsDNA rolling circle
in order for a RNA virus to start replication, what does it require that a DNA virus does not
RNA dependent RNA polymerase
what type of viral genome needs access to the nucleus to start replication
DNA virus
what type of viral genome requires a RNA dependent RNA polymerase in order to start replication
RNA virus
what is the major factor of eradication of a virus
host range (tropism)
- easier to eradicate if only infect human hosts
- hard to eradicate if host range is all mammals
what is the major determinent of a virus’ host range (tropism)
attachment
which needs an RNA dependent RNA polymerase in order to start replication,
(+) sense ssRNA or (-) sense ssRNA
(-)sense ssRNA
all virus/ rely on what host organelle to produce their own viral proteins ?
ribosomes cuz virus have NONE
What are the 3 ways of release after replication that help classify viruses
- Lysis
- weak lysis
- Budding
what specific type of viruses are released via budding
enveloped viruses
when examining the replication kinetics of viruses, what type of growth curves are used
one step growth curves
T/F viruses are obligate intracellular parasites
T
when are virus’ considered “alive”
when they are inside the cells
