Module 7 Flashcards
Viruses
when were viruses first identified
with what disease
1892
tobacco mosaic disease
5 characteristics of viruses
genetic element in protein shell (capsid)
DNA or RNA not both
double, single stranded
segmented or non segmented
naked or enveloped
why are viruses not considered to be living
do not have cellular components/metabolism
fully dependent on host for energy and protein synthesis
name of the extracellular form of a virus
viron
type of microscopy to see viruses
TEM
viral genome components
dna or rna
1000-2.5 mega base pairs
7-1000 proteins
capsid
made up of 1 or more protein subunits called capsomeres
can be self assembling or require host involvement
2 primary symmetrical shapes of viruses
rod with helical symmetry
spherical with icosahedral symmetry
what is width and length dependent on in helical symmetry
width: size/packaging of capsomeres
length: nucleic acid strand length
icosahedral symmetry geometry
20 triangular faces and 12 vertices
simple and most effective assembly
example of a complex virus shape
icosahedral head with helical tail
complex means no symmetry
naked virus components
capsid
nucleic acids
enveloped virus components
membrane
capsid
nucleic acids
how are phospholipid layers derived in viruses
from host during exocytosis
fibrils
peptidoglycan like polymers on amoeba viruses
spike proteins
on the surface of viruses
one type to bind
one type to release
enzymes in bacteriophages
lysozyme like
cut away enzyme to get new DNA in
enzymes in RNA viruses
replicate RNA without template
enzyme in retroviruses
reverse transcriptase (RNA–>DNA)
why are viruses not on the tree of life
they do not have rRNA
writing virus names
species is italic
viral is not italic
name of virus classification system
baltimore classification
factors affecting how a virus infects a host
host
baltimore classification
type (naked/enveloped)
process of phage infecting bacteria (five)
attachment (binding to specific surface receptors)
penetration (viral DNA enters host cell)
biosynthesis (phage DNA replicates, phage proteins are made)
maturation (new phage particles assembling)
lysis (cell lyses releasing baby phages)
steps of a one step growth curve (three)
inoculation (binding)
eclipse ( virions penetrate the cell)
burst (host cell releases viral particles)
burst size
number of virions released per bacterium
what type of viruses exhibit a one step growth curve
lytic viruses as they lyse out all at once
gram + receptors
flagellum
PIP
CWPS
LTA
WTA
gram - receptors
flagellum
pili
porin
LPS
CPS
EPS
infection process of temperate phages into bacteria (four decriptive steps)
phage infects bacteria
phage DNA incorporated
cell divides and passes on incorporated DNA
prophage DNA is excized under stress so it can spread
what is a lysogen
bacteria with a phage integrated into its bacterial genome or as a plasmid
what is lysogenic/phage conversion
phage changes the bacteria’s (lysogen’s) phenotype
viral infection of eukaryotes process (six steps)
attachment (virus binds to target cell)
penetration (cell engulfs virus through endocytosis)
uncoating (viral content is released inside the cell)
biosynthesis (viral RNA enters nucleus, replicated)
assembly (new phage particles made)
release (viral particles are released without killing the cell)
lytic infection
cell must be lysed to release
types of persistent infection, describe
latent-virus is dormant and reactive to stimuli
chronic-virus is not eliminated, continuous production
types of cancer infections, describe
direct-inactivation of safeties
indirect- chronic infection
antigenic drift
change in some of the spike proteins
antigenic shift
combination of two viruses spike proteins to make a new virus
how do viruses acquire their envelopes
during the release phage while budding off
in order to grow viruses you need
living host cell
host cell type that support infection (receptor)
conditions to grow host
quantification of virus (plaque for lytic virus)
plaque is only found
in lytic viruses
how to quantify number of viral genome in a cell without a microscope
qPCR
in DNA the positive strand is
the negative strand is
+: sequence=mRNA, cant be translated
-: sequance to use as a template to make an mRNA sequence
in RNA the positive strand is
the negative strand is
+: template for translation
-:cannot be template
in DNA you need ___ strand to make mRNA
negative
in RNA you need ___ strand to make protein
positive
BC1
double stranded DNA virus
BC2
single stranded DNA virus
BC3
double stranded RNA virus
BC4
positive sense RNA virus
BC5
negative sense RNA virus
BC6
reverse transcribing RNA viruses
dsDNA virus processes
go through replication
go through transcription (neg temp, pos mRNA), translation
ss DNA virus process
must replicate first
then can replicate or go through transcr and transla
dsRNA virus process
go through replication
go through transcr, transla
+ sense RNA virus process
pos strand replicates, replicates again
pos strand can go through translation
-ve sense RNA virus process
neg strand can replicate x2
neg stand can transcribe then translate
reverse transcribing RNA virus process
goes through reverse transcription then replication
after, it can replicate or go through transcr and transla
