1. VIRUSES

2. The Genetics of Viruses  (L) poison  First identified by Stanley in 1935- Tobacco Mosaic Virus  A genome w/in a protective coat

3. Viral Structure  Capsid-protein coat that encloses the genome  Envelope-membrane that cloaks some capsids  Genome

4. Life Cycle  Obligate intracellular parasites  Range varies, depends upon receptor sites  Some with broad range-ex. Rabies  Some with very narrow range-ex. Human cold virus

5. Genome Replication  DNA  DNA uses host DNA polymerase  RNA  RNA virus has gene for RNA replicase  RNA  DNA  RNA usually virus contains gene for reverse transcriptase

6. Lytic Cycle  Virus uses cells enzymes, ribosomes, tRNAs, amino acids ATP, etc.  Viral particles self- assemble  Lytic cycle is fatal to cell  Called Virulent viruses

7. Lysogenic Cycle  Virus coexists within the host  Called temperate viruses  Viral genome is incorporated into the host’s genome  Called a Prophage

9. Animal Viruses

10. Reproductive cycles of Animal Viruses  Attachment-glycoprotein spikes attach to receptor sites  Entry-envelope fuses with plasma membrane, entire virus moves in via receptor mediated endocytsis  Uncoating- genome exposed  Viral RNA and protein synthesis  Assembly and release- virion “buds” through the surface, envelope is cells phospholipids with virus-specific glycoproteins

11. Influenza Animation  http://www.rpc.msoe.edu/cbm/resou rces/HAAnimation.swf http://www.rpc.msoe.edu/cbm/resou rces/HAAnimation.swf http://www.npr.org/templates/story/ story.php?storyId=114075029ttp://www.npr.org/templates/story/ story.php?storyId=114075029

13. Emerging Viruses  Make a sudden appearance.  Not new, just a new territory  Examples: HIV, hantavirus, Ebola  Flu

14. Viruses and Cancer Some tumor viruses cause cancer in animals VIRAL GROUP  Retrovirus  Herpesvirus  Papovavirus  Hepatititis B virus CANCER TYPE  Leukemia  Burkitt’s lymphoma  Cervical cancer  Liver cancer

15. Plant Viruses  RNA viruses  Spread by horizontal transmission- from an external source  Vertical transmission-from parent

16. Viroids and Prions  Viroids are naked circular RNA  Probably disrupt metabolism, development, and growth  Plant pathogen  Prions are proteins  Cause degenerative brain diseases  “mad cow” disease  Creutzfeldt-Jakob disease  How? Hypothesis- misfolded and convert normal proteins to the prion version. Chain reaction.

17. Prion  “proteinaceous infectious particles”  Found in brains of all mammals  Products of gene expression  Some exist in a misfolded state, leads to ability to resist conventional sterilization  Infectious types are able to “latch” onto normal prions and convert them to that infectious type

18. How Prions reproduce

19. 19.12 Prions Change Shape Slide number: 1 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Scrapie PrP All scrapie PrP Normal PrP Original scrapie PrP molecule Converted molecule Normal PrP

20. 19.12 Prions Change Shape Slide number: 2 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm

21. 19.12 Prions Change Shape Slide number: 3 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Normal PrP Scrapie PrP

22. 19.12 Prions Change Shape Slide number: 4 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Normal PrP Scrapie PrP

23. 19.12 Prions Change Shape Slide number: 5 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Original scrapie PrP molecule Normal PrP Converted molecule Normal PrP Scrapie PrP

24. 19.12 Prions Change Shape Slide number: 6 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Original scrapie PrP molecule Normal PrP Converted molecule Normal PrP Scrapie PrP

25. 19.12 Prions Change Shape Slide number: 7 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Nucleus Cytoplasm Intracellular membrane Original scrapie PrP molecule All scrapie PrP Normal PrP Converted molecule Normal PrP Scrapie PrP

26. 19.12 Prions Change Shape Slide number: 8 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus

27. 19.12 Prions Change Shape Slide number: 9 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane Normal PrP Scrapie PrP

28. 19.12 Prions Change Shape Slide number: 10 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane Normal PrP Converted molecule

29. 19.12 Prions Change Shape Slide number: 11 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane

30. 19.12 Prions Change Shape Slide number: 12 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane

31. 19.12 Prions Change Shape Slide number: 13 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane

32. 19.12 Prions Change Shape Slide number: 14 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane

33. 19.12 Prions Change Shape Slide number: 15 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Neuron Cytoplasm Nucleus Intracellular membrane

34. 19.12 Prions Change Shape Slide number: 16 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. All scrapie PrP Neuron Cytoplasm Nucleus Intracellular membrane

35. Videos and Websites  http://www.npr.org/templates/story/ story.php?storyId=114075029 http://www.npr.org/templates/story/ story.php?storyId=114075029  http://www.biology.arizona.edu/cell_ bio/tutorials/pev/main.html http://www.biology.arizona.edu/cell_ bio/tutorials/pev/main.html