Chapter 12: viruses Flashcards
viruses are a)….
Acellular
Viruses reproduce by
host cells
Viruses cause either a) or b).. to the host cell
a) debilitation and or b) death
How viruses invade cells
- a virus a) … a cell.
- Substances in the cell begin to strip off the virus’s b) … of protein.
- The c) … in the center of the virus is released.
- the nucleic acid gets into the cell’s d) …
- the cell ignores it’s own chemical needs and switches to e) …
- The cell is sometimes f)… in the process. Many of the new viruses are released to infect other cells.
a) enters
b) outer coat
c) nucleic acid
d) chemical manufacturing system
e) making new viruses
f) destroyed
The capacity of a the virus to infect a particular group of host species
host range
the range of tissue types a virus can infect
tissue tropism
both tissue tropism and host depend on various host factors, most importantly?
surface receptor molecules
Phages that can undergo lysogeny, are called
temperate phages
phages that reproduce entirely by the lytic cycle and thus are called?
virulent phages
a condition in which the phage genome is replicated along with that of the host cell as the host reproduces
lysogenic cycle: the prophage will eventually get the ability to generate a lytic burst.
Viruses or their genome can be either
- RNA or DNA
- double or single stranded
Why are antivirals hard to make and find?
- viral diseases are in host cells.
- would need to kill host cells.
- hard to develop treatment
the a)… keeps the viral genome intact outside the host
capsid
a)… formed out of the host membranes with embedded viral envelope proteins in some species
envelope, this does not occur in all viruses
ICTV classifies viruses based on these three factors
1) capsid form (icosahedral or filamentous)
2) envelope (present or absent)
3) host range
- The envelope bristles with virus-encoded a) … that plug the membrane onto the capsid.
- The a) … enable the virus to attach and infect the next host cell.
spike proteins
Icosahedral capsids
radial symmetry, based on icoshadron, a polyhedron with 20 identical triangular faces
example of a virus with a Icosahedral capsid
herpes simplex virus
Filamentous capsids
helical symmetry.
* a helical tube around the genome.
* generating a flexible filament.
example of a filamentous capsid virus
Ebola virus
complex-tailed bacteriophage ** head or tail?**
- icosahedral protein package.
- contains genetic material.
head
complex-tailed bacteriophage ** head or tail?**
injects genetic material into host cells
tail
amorphous or complex viruses
have no symmetrical form
example of a amorphous or complex viruses
small pox virus
- small genomes
- retroviruses
RNA
- large genome
- herpes simplex virus
DNA
antigentic shift
rapid mutation
antigenic drift
slow mutation
whats causes new strains of viruses
changes in the genome
The baltimore model
Group 1
* herpesvirus
- double stranded DNA
- straight to mRNA
baltimore model
group 2
* parvovirus
- single stranded DNA
- to dsDNA
- to mRNA
baltimore model
group 3
* Rotavirus
- double stranded RNA
- RNA-dependant
- RNA polymerase
- than mRNA
baltimore model
group 4
* Coronavirus
- single stranded RNA (+)
- RNA-dependant
- RNA polymerase
- than mRNA
baltimore model
group 5
* influenza virus
- single stranded RNA (-)
- RNA dependant
- RNA polymerase
- mRNA
- ssRNA (-) for viral genome
baltimore model
group 6
* retrovirus
- single stranded RNA (+)
- (reverse transcriptase)
- dsDNA
- ** mRNA**
group 7
* Hepadnavirus
- double stranded DNA
- mRNA
- (reverse transciption)
- dsDNA for viral genome
