chpt 13: viruses Flashcards
why are viruses considered alive
cuz they cause infection and disease
what makes viruses viruses
- contain single type of nucleic acid (DNA or RNA)
- contain a protein coat
- multiply inside cells
- cause synthesis of specialized structures
what are bacteriophaes/ phages
viruses that infect bacteria
fully developed infectious composed of nucleic acid and surrounded by a protein coat outside a host cell is
virion
are virions obligate parasites
virion
what makes a virion a virion
- genome or DNA or RNA
- caspid
- envelope (sometimes)
- spkies (sometimes)
what separates virions into categories
genome
what is caspid made of
- protien coat
function of capsid
- protection for genome
- attachment to host cell
what takes up most of the mass of the virus
capsid
what is made of protein, CHO or phospholipids
envelope
location of envople
on top of capsid
what determines the proteins of envelope
viral nucleic acid and from host
what are spikes made of
- protein
- CHO
= glycoprotein (GP)
function of hemeaggulitation spike (HA)
- used for entry into host cell
what causes mutations in HA
protein changing in spike
what is used for identity of viruses
spikes (HA)
what is used to leave host cell
- neuraminidase spille (NA)
what kind of genome does HIV have
2 identical RNA strand
how does HIV infect
- attachment
- fusion
- entry
- multiply
structure of HIV
- genome
- capsid
- envelope
- GP spike
what kind of GP does HIV have
- gp-41
- gp-120
what is enzyme-reverse transcriptase
enzyme that HIV carries
- uses viral RNA as template to produce complementary double stranded DNA
where does HIV bind to human cells
CD4 receptor on Th
what is it called when RNA turns to DNA
reverse transcription
provirus is
an virsus that makes new molecules for itself within the host, makes more DNA
- viral DNA intergrade into host cell chromosome
how does medication attack HIV
- attacks the reverse transcription process
how does medication attack HIV
- attacks the reverse transcription process
how is viral load determined
based on number of virions in blood
how many virons does it take to cause an infection
1 or 2
what kinda of infections can occur after having HIV for a while
- cancer
- fungal
- herpes
when is there a 50% decrease in CD4 count
stage A of HIV
how is rate of infection. likelihood of one being infected occurred
amount of CD4 present
- more CD4 = less likely to be infected
what happens in stage B of HIV
- count drops to 499-200
- cancer can occur
at which stage of HIV is the CD4 less than 200
stage C
once the viral DNA is the host cell does it come out
no
first step in viral maturation
- assembly of protein capsid
budding is
process of envolpe developing
extrusion of virus from host cell =
method of release
how does a non-envolpe virus release
through ruptures in host cell pls mem = death of host
where does RNA of a virus multiply
in the cytoplasm
where is RNA- dependent RNA polymerase made
in host cell
active infection is
- making new virion and regeneration
examples of latent infection
- simplexvirus/ cold sores
hiding and reemerging of an infection is known as
latent infection
why is it difficult to make a vaccine for HIV
mutations
retrovirus is
a RNA virus that has enzyme reverse transcriptase
lytic infection is
acute, virus eventually kills all cells
a cold is an example of
a lytic infection
what type of infection can go on for years with virions building up
persistent infections
meseasles and HIV ____ infections
persistent
what affects brain cells and causes brain degeneration
meseasles
latent infection function
- acute infection at some point, hides and reemerge with new virions and symptoms
fever blisters/ cold sores, shingles / chicken pox = ____ infection
latent
what type of infection converts normal cells to cancer cells
oncogensis infection
examples of ocognesis infection
- kerp
- burkittis lymphoma (herpes-4) = oral cavity tumor
- nasophrangyeal cancer (herpes-4)
