1. Viruses Something you don’t want to catch…

2. Viruses 1. How do scientists classify things as living? 1.Made of cells 2.Has a metabolism to grow and reproduce 3.Information stored in DNA 2. Are viruses alive?

3. Viruses 1. How do scientists classify things as living? 1.Made of cells 2.Has a metabolism to grow and reproduce 3.Information stored in DNA 2. Are viruses alive? NO!

4. Living or Nonliving?

5. Viruses 3. What do viruses and living organisms have in common? Both use nucleic acids to store genetic information in the form of DNA or RNA Both change over time (evolve)

6. Viruses 4. If viruses do not have their own metabolism to grow and reproduce, how do they survive? By hijacking living cells and using their metabolism to grow and reproduce.

7. There are 2 ways virus replicates. Lytic infection- a virus enters a cell, makes copies of itself, and causes cell to burst. Lysogenic infection- a virus integrates its DNA into the DNA of the host cell, and the viral genetic information replicates along with the host cell’s DNA.

8. Lytic Infection (Cycle) First, the virus gains entry to the cell by connecting with cell receptors. Second, the viruses’ DNA or RNA is injected into the cell.

9. Lytic Infection (Cycle) Third, viral nucleic acid replicates and takes over the cell.

10. Lytic Infection (Cycle) Fourth, new viral particles are packaged and released from the cell.

11. Lytic vs. Lysogenic Viruses with lysogenic replication, lay dormant until the cell is replicated during mitosis. WHAT’S THE DIFFERENCE?

12. Lytic vs. Lysogenic CHECK POINT

13. Lytic vs. Lysogenic Lytic CHECK POINT

14. Lytic vs. Lysogenic CHECK POINT Lysogenic

15. Virus Types Bacteriophages = are viruses that attack bacteria Retroviruses = viruses that use RNA to reverse transcribe DNA that integrates into the host genome. Example: HIV

16. More Virus Types What makes these viruses different from bacteria?

17. More Virus Types What makes these viruses different from bacteria? THEY ARE NOT LIVING !

18. CHECK POINT This graphic shows a virus’ _____ _______. A.Viral Replication (Reproduction) B.Viral Transcription

19. CHECK POINT This graphic shows a virus’ _____ _______. A.Viral Replication (Reproduction) B.Viral Transcription

20. How do you treat a virus? Remember you cannot treat a viral infection but you can prevent one by getting a vaccine / IMMUNIZATION.

21. Vaccine A vaccine improves immunity to a particular disease.

22. How do vaccines work? http://health.howstuffworks.com/adam-200097.htm A vaccine contains a weakened strain of the microbe. When injected into your body it stimulates your immune system to recognize it as foreign, destroy it, and remember it. So if your body encounters the full strain later, it can easily recognize and destroy it!!!!!

23. Important facts about viruses Viruses must be produced within living cells Viruses destroy the living cells they grow in Viruses gain entry by specific receptors on the host cell SUMMARY

24. Viruses How do you catch many viruses? Through body fluids.

25. Hepatitis and the HIV/AIDS are exchange during sexual contact or blood transfer. Both have long incubation periods- so it is a long time before a person knows they are sick. Hepatitis attacks white blood cells then your liver cells so your body can no longer filter your blood. HIV attacks white blood cells and destroys your immune system- so you die of minor infections. EXAMPLES OF Diseases Caused By VIRUSES