Term
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Definition
| -porcelain filters used to filter (remove) bacteria |
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Term
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Definition
| some filtrates remained infectious |
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Term
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Definition
"Contagium vivium fluidium" (Contagious living fluid)
- later coined the name "virus" (meaning poison or venom)
- prior to 1930's: lack of technology needed to : isolate, propagate, observe and analyze was not available |
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Term
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Definition
| -crystallized the first virus (TMV) consisted of protein and RNA |
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Term
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Definition
| - virus first observed with an electron microscope |
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Term
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Definition
- mendel's particles
- certain inherited traits seem to be passed from parent to offspring as discrete hereditary "particles" |
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Term
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Definition
| -genetic material of some viruses was DNA |
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Term
| general characteristics and structure of viruses |
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Definition
- contain a single type of nucleic acid, either DNA or RNA
- contain a protein coat (CAPSID) around the nucleic acid
- consists of protein subunits called capsomeres
- is antigenic/immunogenic (stimulates antibody production)
- some viruses have an envelope around the protein coat
- multiply inside living cells (viruses can't synthesize proteins or generate ATP)
- viruses take over the metabolic activity of host cells
- important for clinical control: difficult to disrupt viral replication without interfering with host clel function |
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Term
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Definition
| most only seen with an electron microscope (20 - 14,000 nm) |
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Term
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Definition
helical/spiral.
-icosahedral (20 sided polyhedron)
- enveloped; complex |
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Term
| environmental effects on viruses |
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Definition
- heat: most are destroyed by >60 C, 140 F
- cold: little effect (survive -76 C over 1 yr.)
-dessication: tolerates drying
- pH: tolerates pH 5 - 9
- disinfectants: most are ineffective, disinfectant destroys metabolic activity, virus don't have metabolic activity,
- alcohol can destroy lipid enveloped viruses
- oxidizing agents are MOST effective (e.g. hydrogen peroxide, chlorine, iodine)
- UV light damages nucleic acid |
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Term
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Definition
- requires LIVING CELLS
- living animals and plants
- embryonated eggs: virus is injected into embryonic tissues and membranes
- tissue/cell culture: cells in solution that provides: nutrients, proper osmotic pressure, pH etc.
- primary cell and embryonic diploid cell lines: grow for a short time in vitro (in test tube/glass)
- continuous/immortal cell lines: can be maintained in vitro indefiitely
- bacterial culture |
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Term
| T-even bacteriophage lytic cycle |
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Definition
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Term
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Definition
phage tail fibers attach to specific receptors on bacteria
- penetration: phage release enzyme
- lyzozyme: dissolves part of the bacteria cell wall, tail sheath contracts and drives phage core through the cell wall
- biosynthesis: viral DNA takes over the machinery of the host cell and begins producing viral DNA and structural components
-maturation/assembly: phage DNA assembles into complete viruses
- release/lysis: phage lysozyme breaks down bacterial cell wall and multiplied phages are releasede.
- "burst time": time from adsorption to release. the average number of virons released by a cell (50 - 200 T-even virons for T-even phage) |
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