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16 Cards in this Set
- Front
- Back
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What did Walter Reed show, transmitted by? |
person who showed that yellow fever caused by virus, transmitted by mosquitos |
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Virus size/genome length |
10-100nm (generally) genome is 1-200k BP long |
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Exceptions to virus size/genome size? (3) |
Mimivirus: up to 400nm in dia, 1.2Mbp genome Megavirus chilensis: over 1.2Mbp genome, 1.2k proteins Pandoravirus: 2.5Mbp 1 micron in dia |
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Viral Structure |
single/double stranded DNA (lin/circ) Protein capsid around genome (nucleocapsid) some have envelope around |
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Capsid shapes |
Often helical/icosahedral, can be irregular/complex shapes |
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Enveloped virus vs. naked differences |
enveloped has a plasma mem surrounding nucleocapsid naked has no plasma mem |
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Viral replication cycle (6 steps) |
adhere, enter, uncoat (release genome), synthesis, assembly (create new virus particle), exit (new particles leave) |
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How do viruses enter the cell? (plant and animal) |
Tag onto HIV and CD4 recep on t4 cells in animal cells, dont need to worry about cell wall. In plants they can use damage caused by wind, bugs, humans, fire, wind |
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How does a virus enter bacterial cells? (4 steps) |
Taill attatch to receptor base of tail comes in contact with cell surface inner tube proteins extend into cell wall DNA comes through newly formed pore |
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2 cycles of bacteriophage and how it happens |
lytic: phage entering cell, lysing host cell lysogenic: integrate viral genome into bacterial genome (prophage), replicated alongside normal genome until stress |
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Cultivation of Bacteriophage |
Add bacterial host cells to phage sample, add molten agar pour into petrie dish |
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Cultivation/Purification of Animal Viruses |
Tissue from target harvested, or use chicken/duck eggs keep sterile and bacteria free new practice use filtration to remove large cells/debris conc. with centrifugation gradient centrifugation: put in layers of conc. of sucrose, forms layers |
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Viral Quantification Methods (4) |
Direct counting (using e- microscope) hemagglutination assay: add RBC, only some will do, doesnt give # Plaque assay: dilute, place on target cells, count to det titer of original sus. (good for pahges/plant virus Endpoint Assay: shows amount of virus to induce 50% of cells to show CPE (structural change) or to kill 50% organisms |
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Methods of naming (3) |
Naming based on feature, place, infected animal (old way) ICTV: bases it on genus, species Baltimore Classification: based around mRNA production, seperates into 7 classes |
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Virus Identification (2 methods) |
e- microscopy: visual morphology (not a sure thing) Nucleic Acid Analysis: Use PCR to sequence genome, can be used to study evolution patterns |
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Viroids/Prions (structure/niche) |
viroid: just naked RNA, <400 nucleotides, resistant to ribonucleases only in plants Prion: just proteins, responsible for mad cow diesease, replication method unknown (maybe change from normal to abnormal conformations |
