1. 19-3 Viruses Are they alive? Acellular Can not metabolize Can’t grow or respond to environment Can’t reproduce without host- obligate parasites Have DNA or RNA Evolve *can only be seen with electron microscope Yes No

2. Virion- virus outside of cell Capsid-protein coat surrounding nucleic acid Genetic material- DNA or RNA –dsDNA- double stranded DNA –ssDNA- single stranded DNA –dsRNA- double stranded RNA –ssRNA- single stranded RNA Super small amount of genes Capsomeres- Surface proteins- only attach to particular host or even specific cells in the host

3. Discovery- they were looking for the cause of Tobacco Mosaic Virus 1883- Adolf Mayer-disease is contagious 1892- Dmitri Ivanovsky- uses filter to trap “bacteria” 1897-Martinus Beijerinch- caused by something smaller than bacteria 1898-named virus- meaning “poison” 1935- Wendell Stanley- isolates virus

4. Bacteriophage Infects bacteria Replication- –2 cycles

5. Enveloped virion Membrane acquired from its host cell during viral replication or release Composed of phospholipid bilayer & proteins- specific for host attachment

6. Lytic Cycle (virulent-causes disease) 1.Attachment - the virus attaches itself to the host cell.Attachment 2.Injection - the virus inserts its genetic material into the host cell.Injection 3.Integration & Replication- the genetic material tells the cell what to do & the host cell builds parts of the virus.IntegrationReplication 4.Assembly - the cell assembles the replicated parts into new viruses.Assembly 5.Lysis - the cell breaks open and each replicated virus can now infect other cells.Lysis

7. Lysogenic Cycle (temperate- doesn’t kill right away) 1.Attachment 2.Injection 3.Integration- virus DNA becomes part of bacterial DNA- prophage 4.Replication- when host cell replicates its own DNA, virus DNA is also copied 5.Assembly 6.Trigger > Lytic Cycle can be caused by sunlight, radiation, chemicals

8. Lytic vs Lysogenic Cycles www.youtube.com/watch?v=wVkCyU5aee Uwww.youtube.com/watch?v=wVkCyU5aee U http://www.youtube.com/watch?v=_J9- xKitsd0&feature=relatedhttp://www.youtube.com/watch?v=_J9- xKitsd0&feature=related

9. How do Animal viruses replicate? Same steps as bacteriophages, just some differences in what is happening in each –Ex: removal of outer coat

10. Latency -viruses remain dormant in cells Prolonged viral activity for years –Ex: chickenpox, herpes Can become integrated into host’s chromosomal information permanently, so all cells after that are infected –Ex: HIV

11. Viroids Small, circular pieces of RNA that are infectious to plants Lack capsids May appear linear

12. Prions Not viruses because they lack nucleic acid Composed of single protein- PrP –All mammals contain a gene that codes for the a.a. sequence for cellular PrP Can re-fold into stable structures, changing shape & become harmful Excess PrP or mutations cause the prion PrP 40% of humans have PrP that can misfold

13. Retroviruses Work “backwards” –RNA > DNA > RNA > Protein –HIV –http://www.youtube.com/watch?v=eS1GODin O8whttp://www.youtube.com/watch?v=eS1GODin O8w

14. Treeman http://www.hlntv.com/video/2013/10/03/tre e-man-genetic-condition-growths-hands- legshttp://www.hlntv.com/video/2013/10/03/tre e-man-genetic-condition-growths-hands- legs

15. Vaccines How are they made? –Reading –http://content.time.com/time/video/player/0,32 068,60312463001_1951560,00.htmlhttp://content.time.com/time/video/player/0,32 068,60312463001_1951560,00.html