Viruses Flashcards
what is a virus
very small infectious obligate intracellular parasite
what is a progeny viron
fromed in host cell
what does a progeny viron do?
means of transmitting of virus to next host cell
what are a viruses properties of life
- cellular respiration
- reproduction
- metabolism
- hereditory
- responcivness
- growth and development
what does a host provide for a virus to reproduce and spread to a new host
> nucleotides for nucelic acids
ribosomes and amino acids for translation of proteins
ATP for enegry
Golgi and ER for protein processing
what are nucleotides useful for
nucleic acids
what are ribosomes and amino acids useful for
translation of proteins
what is ATP useful for
energy
what is the golgi and ER useful for
protein processing
how are viruses categorised (topic and subtopic)
nucelic acid– DNA/RNA
capsid symmetry – helical, icosahedral, complex
presence/absence of envelope– naked/enveloped
genome charictoristics
what makes a virus
nucleic acid (DNA/RNA) protein coat (CAPSID) surrounding nucleic acid sometimes envelope sometime a capsule
describe bacteriophage
infect and replicate within bacteria
highley virulent for bacteria
complex structure
classified by shape and nucleic acid
what is bacteriophage structure
head, collar, tail, tailspins, tail fibres
what is bacteriophage life cycle
- attachment
- penetration/entry (injection)
- Synthesis of nucleic acid and protein
- assembly and packaging
- release (lysis)
describe attachment
> all viruses have attachment proteins on outside
protein attaches to specific receptors on host cell surface
receptors are normal proteins found on outside of the host cell
what is lambada an example of
bacteriphage
describe lambada
bacteriophage, temperate, has 2 life cycles
enters either the lytic pathway or lysogenic pathway depending on series of complicated genetic events
describe lytic cycle
infected bacteria are production factory for lambada and are lysed to release new bacteriophage
describe lysogenic cycle
bacteriophage genome is incorporated into bacterial host chromosome by genetic recombination that occurs at specific sites on chromosome
what is prophage
name for bacteriophage DNA when inserted in bacterial host chromosome
name a plant virus
tabacco mosaic virus
describe tobacco mosaic virus
helical symmetry, 2130 identical capsomers
helical nucleocapsid
Viral DNA
where is envelope on virus derived from
cell, golgi or nuclear membrane
example of enveloped virus
measles/ influenza
describe plaque assay
virus innoculated on monolayer of cells/ bacteria overlay of agar added
virus can only spread from cell to cell
holes or plaques of dead cells in monolayer
modifications are used if virus does not form plaques
what is a plaque layer used for
isolate single virus
name effects of virus infection on cell
- lysis- cell death
- transformation - tumor formation
- cytopathic effect- under microscope
- persistent infection of cell
- latent infection of cell (can become lytic)
describe virus glycoproteins
matrix protein links virus nucleocapsid to membrane.
form spikes on outside of virus
what are glycoproteins the main antigens for
immune systems
describe enveloped virus cell cycle
envelope fuses with cell membrane,
synthesis of nucleic acid genome and viral proteins
ER of cell makes viral glycoproteins
progency viruses bud from cell
cell membrane remains intact doesn’t kill host
what is an envelope
lipid bilayer with glycoprotein spikes
describe human immunodeficiency virus
single stranded
enveloped
retrovirus (RNA)
has virus latency
describe primary cell culture
obtained from live animal tissue – limited life
what is the life of a primary cell culture
limited
describe diploid cell lines
homogenous cells from embryo
divide around 100x then die
where do diploid cell lines come from
embryo
describe continuous cell lines?
imortal cell lines (never stops growing)
usually from cancerous cell
where do continuous cell lines usually come from
cancerous cell
what is virus latency
allows virus to avoid detection by immune system
