1. Virus

2. biological particle/ pathogen virus comes from Latin “poison” living? or non-living? rabies virus Virus

3. First virus Wendell Stanley (1935) studying splotchy leaves on tobacco discovered and isolated tobacco mosaic virus (TMV) Virus

4. Structure of a Virus nucleic acid core (DNA or RNA), surrounded by outer protein coat called a capsid different shapes: hellical (rod), sperical, polyhedral, different sizes 17nm – 100nm some have an envelope with spikes that surrounds the capsid contain no cell organelles, carry out no metabolic reactions reproduce only inside a host cell many are host specific classified by type of nucleic acid and shape Virus

5. Structure of a Virus nucleic acid core (DNA or RNA), surrounded by outer protein coat called a capsid Virus

6. Structure of a Virus different shapes: hellical (rod), sperical, polyhedral, different sizes 17nm – 100nm Virus

7. Structure of a Virus some have an envelope with spikes that surrounds the capsid HIV Virus

8. Structure of a Virus many are host specific –ex: bacteriophage only infects bacteria Virus

9. Structure of a Virus contain... no cell organelles, carry out... no metabolic reactions reproduce... only inside a host cell Virus

10. Structure of a Virus classified by type of nucleic acid and shape Virus

11. Viral Reproduction Lytic Cycle (DNA virus) –virus takes over host cell, replicates, and destroys host cell Steps –attachment –entry –replication –formation & assembly –lysis & release Virus

12. Viral Reproduction Lytic Cycle (DNA virus) viruses use nucleotides, ribosomes, tRNA, and amino acids of host cell viruses that undergo the lytic cycle are called virulent – short incubation time rhino virus Virus

13. Viral Reproduction Lytic Cycle (DNA virus) Virus

14. Viral Reproduction Lysogenic Cycle (DNA virus) –virus invades cell and becomes part of its DNA for a time Steps –attachment –entry –intergration viral DNA breaks open host cell DNA and joins with it forming a provirus –cell division host cell divides, produces 2 new host cells with the provirus inside Virus

15. Viral Reproduction Lysogenic Cycle (DNA virus) provirus may: –change phenotype of host –prevent other viruses from entering host –pull out of host DNA & enter lytic cycle Virus

16. Viral Reproduction Lysogenic Cycle (DNA virus) viruses that go through lysogenic cycle are temperate viruses – long incubation period herpes simplex Virus

17. Viral Reproduction Lysogenic Cycle (DNA virus) Virus

18. Viral Reproduction Lysogenic Cycle (DNA virus) Virus

19. Viral Reproduction RNA virus Lytic cycle Steps (almost the same as DNA virus) –attachment –entry –replication replication of viral RNA –formation & assembly –lysis & release Virus

20. Viral Reproduction RNA virus Lysogenic cycle Steps inject viral RNA into host viral RNA makes a DNA copy using reverse transcriptase DNA strand replicates and enters host DNA to become a provirus Virus

21. Viral Reproduction RNA virus Lysogenic cycle RNA viruses that go through the lysogenic cycle are called retroviruses HIV Virus

22. Treating Viruses vaccine injection of weakened or killed viruses Jonas Salk (1955) developed first vaccine for the polio virus Virus

23. Other Viruses polio Virus

24. Other Viruses measles Virus

25. Other Viruses smallpox Virus