Virus

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Virus

  1. 1. Virus
  2. 2. Core concepts <ul><li>A virus is a non-cellular particle which consists of a core of nucleic acid (DNA or RNA) surrounded by a protein coat (capsid). It is an infectious agent that is only capable of metabolism and reproduction within a living cell. </li></ul><ul><li>In order to reproduce, viruses must infect a host cell in one of two ways: through a lytic or a lysogenic cycle. </li></ul>
  3. 3. Key words <ul><li>Virus capsid </li></ul><ul><li>bacteriophage/phage lytic cycle </li></ul><ul><li>lysogenic cycle virulent phage </li></ul><ul><li>temperate phage prophage/provirus </li></ul><ul><li>Retrovirus reverse transcriptase </li></ul><ul><li>Viroid prion </li></ul><ul><li>Interferon vaccine </li></ul>
  4. 4. Dmitri Iwanowskie and the TMV <ul><li>Ukrainian biologist and founder of virology </li></ul><ul><li>Adolf Mayer suggested an infectious agent affecting tobaccos </li></ul><ul><li>Using the steps in the Koch’s postulate he was able to extract the tobacco mosaic virus </li></ul>
  5. 5. TMV
  6. 6. Virus structure
  7. 9. Virus <ul><li>“ Organisms at the edge of life” </li></ul><ul><li>Have genes, evolve, reproduce(self-assembly) </li></ul><ul><li>No cellular structure (unit of life) </li></ul><ul><li>Do not have own metabolism (requires host) </li></ul><ul><li>Need host cell to reproduce </li></ul><ul><li>Governed by natural selection </li></ul><ul><li>Gives proof to chemosynthetic theory </li></ul>
  8. 10. Taxonomy <ul><li>Order (-virales) </li></ul><ul><ul><li>Family (-viridae) </li></ul></ul><ul><ul><li>Subfamily (-virinae) </li></ul></ul><ul><ul><li>Genus ( -virus ) </li></ul></ul><ul><ul><li>Species ( -virus ) </li></ul></ul>
  9. 11. Classification <ul><li>Genetic Material </li></ul><ul><li>Shape </li></ul><ul><li>Size </li></ul><ul><li>Presence of envelope </li></ul><ul><li>Specificity </li></ul><ul><li>Disease type </li></ul>
  10. 12. Genetic material <ul><li>DNA virus </li></ul><ul><li>RNA virus </li></ul><ul><ul><ul><li>Also called retrovirus </li></ul></ul></ul><ul><ul><li>If a virus has a single stranded genetic material it is more prone to mutation </li></ul></ul>
  11. 13. Viral infection <ul><li>Very Specific </li></ul><ul><li>Binds to surface receptors </li></ul>
  12. 14. Lytic Cycle
  13. 15. Lysogenic Cycle
  14. 16. Lytic and Lysogenic cycle
  15. 17. The retrovirus and HIV <ul><li>Whys is a retrovirus very dangerous? </li></ul><ul><ul><li>Genetic stability- exists as a provirus </li></ul></ul><ul><ul><li>High expression </li></ul></ul><ul><ul><li>Flexible genome </li></ul></ul>
  16. 19. Possible Origin of Virus <ul><li>pieces of cellular DNA that became part of an infectious particle </li></ul><ul><li>although small and relatively simple, are not likely to have been the first living things on earth since they’re completely dependent on living cells </li></ul><ul><li>may have evolved from genetic material of living cells, and continue to evolve along with their host cells </li></ul>

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