23: viruses Flashcards
What are some distinctions between viruses and bacteria?
viruses are filterable and cannot replicate in broth
What is a virus particle called
virion
What are pithovirus?
discovered in ice core, no rRNA, can have virophage
What are acute viruses?
rapidly kill their host cells and host, act as predators and parasites to limit host population density, increase host diversity
What is a persistent virus?
remain in host where they may evolve traits that confer positive benefits in a virus-host mutualism
Why are viruses essential to the biosphere?
help maintain ecological balance, contribute to host diversification, result in nutritional viral shunt
What are viruses in our gut called?
caliphates: encode virulence factors that are beneficial for bacteria but toxic to us
What are the components of a nonenveloped virus?
genetic material wrapped in a protective capsid, spike proteins attach to host cells and are integrated into the capsid
What are the components of an enveloped virus?
have capsids surrounded by an envelope, which are viral proteins embedded In a phospholipid bilayer derived from membrane in host cell. Attached to capsid via matrix protein
Why is persistent virus more susceptible to death?
bc it has an envelope and is susceptible to dehydration and loss of structure
what is a viroid?
ssRNA virus that infects plants and is transmitted via aphid. Has no capsid, does not encode protein and is replicated by host polymerase, can have catalytic ribozyme that allows for self cleavage and circular genome ligaiton
self complementary
usurp host machine and produce srnas
What is a satellite?
sub viral agents that depend on co-infection with a helper virus for replication
- encode structural protein that encloses nucleic acid
-hepatitis delta virus replicated with HBV
-> B provides out capsid, nucleic acids encapsulated by helper virus protein
What us a prion?
not a virus derived from protein infection
no nucleic acid components
prp proteins found throughout the body
misfolded, protease resistant PrP cause normal prPs to misfold
How many genes are in a giant virus, RNA virus, HPV virus:
e.coli: 5k
giant virus: 300-2500
RNA viruses: 8-12 genes
HPV:
3-5
Viral phylogeny
genomic sequencing, based on ortholog comparison, homologies present despite lack of nucleic acid homology
What kind of reproduction can viruses do?
Lytic, lysogenic, slow release: virus continually released w/o killing cell
What is step one of the virus life cycle?ep
- attachment
What is step two of the virus lifecycle?
eclipse period
2a: disassembly of infectious particle
2b: replication of viral genome
Step 3 of virus lifecycle?
latent period
3a: replication of viral structural components
3b: reassembly of replicated pieces into progeny virus particles
Step 4 of virus lifecycle?
4a: release of visions from host
filamentous phages
capsid has capsomeres, long helical symmetric tubes, surround genome, vary in length and size
What are spikes?
viral proteins that attach to host cell and are integrated into capsid
