Chapter 5 - viruses Flashcards
Viruses are _____________ ________ _________ (meaning they cannot function outside of a host cell).
intracellular obligate parasites
Viruses are typically between __ and ___ nanometers.
10 and 100
Virus genomes are typically between a few thousand to ______ nucleotides in length.
200,000
Viruses may contain ______ OR _______-stranded DNA or RNA.
single or double
The protein shell around a genome is called a ______.
capsid
Capsids are composed of many __________ proteins.
capsomere
When a capsid and genome are together, the structure is called a ____________.
nucleocapsid
Viruses could possibly have an ________ (plasma membrane taken from a host cell around the capsid).
envelope
Capsids often exhibit either _______ or ___________ (sometimes called polyhedral) shapes.
helical, icosahedral
If a plasma membrane surrounds the nucleocapsid, the virus is “_________.”
enveloped
If there is no plasma membrane, the virus is “_____.”
naked
Enveloped viruses are mostly associated with _______ (including ______) as their hosts.
animals, humans
A virus must:
- stick to a host cell (______)
- get into the cell (_________) and release its genome (______)
- express its genes to make proteins (_________)
- replicate its genome (_________)
- put everything together (________) and get the new virus particles out (____)
adhere, penetrate, uncoat, synthesis, synthesis, assembly, exit
In the replication cycle, _____ is arguably the most important part in the viral replication cycle.
entry
_________ for entry vary depending on the host cell (animal viruses don’t have to contend with a cell wall structure)
mechanisms
The most common mode of entry int an animal cell is ________ ______ of an enveloped virus.
membrane fusion
Viruses can enter into animal cells through ________ ______ and ___________ of an enveloped or non-enveloped virus.
membrane fusion, endocytosis
Entry into _____ cells depend on damage to tissues and open spots in the cell wall.
plant
These factors can allow for viruses to enter into plant cells:
insects feeding on plants
wind damage
hail/rain damage
fire damage
human-induced damage
Viruses enter into ________ by punching a hole into the cell wall and transferring DNAA through the hole.
bacteria
In _____ replication cycle, phages replicate inside host cells and burst open/lyse them to spread.
lytic
In _________ replication cycles, the phages integrate their genome into the host cell’s genome and is replicated each time the host cell replicates.
lysogenic
When a phage integrates their genome into the bacterial host cells genome, it becomes a ________.
prophage
To cultivate animal viruses, ______ _______ of host cells must be used to grow the targets for the viruses.
tissue culture
Tissue cultures must be kept _______ and ________-____.
sterile, bacteria-free
Structural changes in host cells that are caused by viral infections.
cytopathic effects (CPE)
Viral ______________ is the measurement of the quantity of a virus.
quantification
Viruses are usually measured as a _____, or concentration of a virus preparation.
titer
Method of viral quantification where one counts the viruses within the material and scaling up to determine titer.
direct count
Method of viral quantification that is useful in phages and plant viruses.
plaque assay
The ____ ______________ ______ classify viruses based on Order, Family, Subfamily, Genus, and Species.
ICTV classification scheme
ICTV =
International Committee on Taxonomy of Viruses
The _________ ______________ ______ is based around mRNA production methods and separates viruses into seven classes.
Baltimore classification system
_______ consists only of naked RNA (infectious RNA strands).
viriods
Viroids are only a=observed to cause disease in ______.
plants
_________ viruses require a helper virus for their replication (e.g. hepatitis).
satellite
Satellite ____ also require helper virus for replication.
RNAs
______ are thought to revolve around conversion of protein conformations from normal to abnormal form over time.
Prions
Prions are responsible for _____________ ___________ ________________ (TSEs), such as mad cow disease and kuru.
transmissible spongiform encephalopathies
Viruses are exploited to deliver working copies of genes to replace damaged versions =
gene therapy
