microbiology lecture six

what is a virus

not a living cell

what does a virus infect

living host cells to replicate

what does a virus always have

a small genome

what are capsids

protein coats

what are the sizes of viruses

20-200nm

what do viruses never have

ribosomes

what are icosahedral capsids

20 triangular sides

what are helical capsids

long tube of protein, with genome inside

what coats DNA/RNA

helical capsids

what are complex capsids

mixture of icosahedral and filamentous shapes

what are many bacteriophage shapes

complex capsids

what tends to be asymmetrical shapes

larger viruses

what do many viruses have

lipid envelopes

what do lipid envelopes allow for

fusion to host cell

what is non-enveloped

bacteriophages

what is group I genome, classification and example

dsDNA, poxvirus

what is group II genome, classification and example

ssDNA, parvovirus

what is group III genome, classification and example

dsRNA, epizootic hemorrhagic disease

what is group IV genome, classification and example

(+)ssRNA, poliovirus

what is group V genome, classification and example

(-)ssRNA, influenza virus

what is group VI genome, classification and example

RNA retroviruses, HIV

what is group VII genome, classification and example

DNA pararetroviruses, hepatitis B

what is transcription

DNA turning into RNA

what is translation

RNA turning into a protein

what must all viruses do

attach to host cell, get viral genome into host cell, replicate genome, make viral proteins, assemble capsids, release progeny viruses from host cell

what to viruses inject genomes through

cell wall to cytoplasm

in the Hershey-Chase experiment what was labeled with 35S Methionine

protein

in the Hershey-Chase experiment what was labeled with 32P Phosphate

DNA

what is the lactic cycle

phage quickly replicates, kills host cell

what is the lysogenic cycle

phase is quiescent, replicates only when host genome divides

what do bacteriophages use cell components for

synthesize capsids

what is viropexis

when the virus is taken up via endocytosis

where must DNA viruses go

the cell nucleus

what must RNA viruses do

encode a viral polymerase

what can only be used as mRNA

(+)ssRNA

all must all viruses make

proteins with host ribosomes

what is budding

when viruses pass through the membrane and it surrounds the capsid to form an envelope

what is the eclipse period

viruses making proteins, genomes, assembling

what is the rapid rise period

burst of bacteriophage = bacterial lysis
rapid release of eukaryotic viruses

what is a colony of viruses

plaque

what can viruses out compete

bacteria

where are viruses present and often at what

all environments, very high densities

what are viroids

naked RNA

what are prions

defectively folded host protein

what is an example of a prion

creutzfeld-jakob disease