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11 Cards in this Set
- Front
- Back
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What are viruses? |
Obligate intracellular parasites – they cannot reproducewithout cells |
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Size of viruses |
10-400 nm
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Virus structure |
RNA/DNA bound by a protective capsid protein - forming nucleocapsid. Capsids self assemble from protomers
Can have addition layers, on top of protein coat |
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What are capsids? |
Protein coat
Repeating subunits Helical, isosahedral or complex |
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How do viruses replicate? |
Attach to host cell
Entry or nucleic acid/nucleocapsid into host cell Viral genes transcribed/translated Virions self assemble and mature particles are released |
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How to viruses attach to host? |
Surface proteins recognise receptor on host cell membrane
Some have spikes, some use network of interacting surfaces |
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What does the fibre tip recognise? |
Host cell receptor CAR - coxsackie and adenovirus receptor
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Examples of endocytic/non-endocytic route? |
endocytic route: clathrin-mediated endocytosis and penetration - flu non-endocytic route: fusion at the cell surface - HIV |
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What type of DNA do poxviruses have? |
dsDNA
Carry own DNA/RNAPs so replicate in cytoplasm |
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How do retroviruses copy their positive strand RNA genome into dsDNA? |
Reverse transcription DNA is integrated into the host genome by a viral integrase Host RNAPs then generate mRNA for viral protein synthesis and new copies of the viral genome for packaging and release |
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Four major classification criteria |
1. genome structure 2. replication strategy 3. morphology 4. genetic relatedness |
