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Figure 10.22

Figure 10.22. VIRUSES: GENES IN PACKAGES. Viruses Components Infection cycle 3. DNA, RNA viruses 4. Uses of viruses. Components of a virus (phage). 1. Protein coat = capsid 2.genetic material DNA or RNA 3. enzyme. Components of a virus. Membranous envelope. envelope capsid

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Figure 10.22

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  1. Figure 10.22

  2. VIRUSES: GENES IN PACKAGES Viruses Components Infection cycle 3. DNA, RNA viruses 4. Uses of viruses

  3. Components of a virus (phage) 1. Protein coat = capsid 2.genetic material DNA or RNA 3. enzyme

  4. Components of a virus Membranousenvelope • envelope • capsid • genetic material • Ex. flu viruses RNA Proteincoat Glycoprotein spike Figure 10.18A

  5. Phage reproductive cycle Phage DNA directs host cell to make more phage DNA and protein parts. New phages assemble. Phage attaches to bacterial cell. Phage injects DNA. Cell lyses and releases new phages.

  6. Viral DNA may become part of the host chromosome Phage Attachesto cell Bacterialchromosome Phage DNA Cell lyses,releasing phages Phage injects DNA Many celldivisions Occasionally a prophagemay leave the bacterialchromosome LYTIC CYCLE LYSOGENIC CYCLE Phagesassemble Phage DNAcircularizes Lysogenic bacteriumreproduces normally,replicating the prophageat each cell division Prophage OR New phage DNA andproteins are synthesized Phage DNA inserts into the bacterialchromosome by recombination

  7. Glycoprotein spike VIRUS Protein coat Viral RNA(genome) Envelope Plasmamembraneof hostcell Entry 1 Uncoating 2 • Viruses redirect the host cell machinery to make more viruses • Some animal viruses steal a bit of the host cell’s membrane Viral RNA(genome) RNA synthesisby viral enzyme 3 Proteinsynthesis RNA synthesis(other strand) 5 4 mRNA Template New viral genome Newviral protein Newviral proteins Assembly 6 Exit 7 Figure 10.18B

  8. Plant viruses are serious agricultural pests • Most plant viruses have RNA • Example: tobacco mosaic disease Protein RNA Figure 10.19

  9. The deadly Ebola virus causes hemorrhagic fever • Each virus is an enveloped thread of protein-coated RNA • Hantavirus is another enveloped RNA virus • SARS - coronavirus • Avian flu Figure 10.20A, B

  10. HIV, seen here attacking a white blood cell Figure 10.22

  11. HIV is a retrovirus

  12. Invasion of T cell by HIV

  13. HIV infection Figure 10.22x1

  14. AIDS quilt Figure 10.22x2

  15. Uses of Viruses • Pest control • Vaccines • Anti-cancer treatment • Gene therapy

  16. Anti-cancer viruses Makes use of viral ability to enter only cells of one type Allows targeting of therapy to tumor cells Enables identification of small tumor sites

  17. Coming soon to your local pharmacy!

  18. Other parasitic particles • Viroids - infectious RNA (no capsid) • Prions - infectious protein • Cellular PrP, prion PrP • Spongiform encephalopathies cause neural degeneration

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