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Viruses Living a borrowed life

Viruses Living a borrowed life. Discovery of the tobacco mosaic virus. Structure and properties of viruses. Small infectious agent that can only replicate inside the living cell of an organism Virus particles ( virions ) Protein coat/capsid formed from capsomeres

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Viruses Living a borrowed life

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  1. VirusesLiving a borrowed life

  2. Discovery of the tobaccomosaic virus

  3. Structure and properties of viruses • Small infectious agent that can only replicate inside the living cell of an organism • Virus particles (virions) • Protein coat/capsid formed from capsomeres • Nucleic acid core (DNA/RNA) ~ 4-1000 genes • Accessory structures* • Lipid envelope – from membrane of the host cell adenovirus influenza T4 TMV

  4. Virus classification http://3.bp.blogspot.com/_QUryhHJZKbU/S8uRMF8FD3I/AAAAAAAACI0/CINIMHP5Cmc/s320/Rhinotracheitis+Capsid.jpg

  5. Types of animal viruses

  6. Virus reproductive cycles Enveloped Virus

  7. LYTICvslysogenic cycles in dsdna bacteriophages/Animal viruses

  8. examples • LYTIC VIRUSES • influenza • rhinovirus (common cold) • LYSOGENIC VIRUSES • herpes I and II • some retroviruses • MIXED STAGE VIRUSES http://www.slic2.wsu.edu:82/hurlbert/micro101/images/vir5.gif

  9. RNA virus replication Virus RNA  mRNA  proteins

  10. http://www.web-books.com/eLibrary/Books/B0/B22/MAIN/images/HIVcycle.gifhttp://www.web-books.com/eLibrary/Books/B0/B22/MAIN/images/HIVcycle.gif RNA retrovirus replication Virus RNA  DNA  mRNA proteins

  11. HYpotheses on viral origins Viroids – RNA sequences that infect plants • Progressive theory • Genetic material from cells escaped and mutated • Regressive theory • Evolved from bacteria that are obligate intracellular parasites • Virus-First Hypothesis • Evolved from the first RNA segments before the early cells http://blogs.sciencemag.org/origins/WindowsLiveWriter/bc47e94c78c7_9B1A/mutation-v-genome_3.jpg

  12. http://www.slic2.wsu.edu:82/hurlbert/micro101/pages/Chap9.htmlhttp://www.slic2.wsu.edu:82/hurlbert/micro101/pages/Chap9.html Bacterial transductionPhage-mediated DNA transfer

  13. http://liquidbio.pbworks.com/w/page/11135299/f/SwineEvolution.png, http://i2.squidoocdn.com/resize/squidoo_images/590/draft_lens4362032module30604592photo_1241127545geentic_makeup_of_flu.jpg

  14. SIGNIFICANCE OF VIRUSES • pathogens • viral gene therapy • phage typing of bacteria • source of enzymes • pesticides • antibacterial and anticancer agents • molecular biology breakthroughs • genetics and evolution http://en.wikipedia.org/wiki/File:LambdaPlaques.jpg

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