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Viruses Living a borrowed life

Explore the fascinating world of viruses, from their structure and properties to replication cycles and evolutionary origins. Learn about different types, including lytic and lysogenic viruses, RNA retrovirus replication, and the significant role of viruses in biology breakthroughs and genetic research.

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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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