Viruses and Bacteria

1. Viruses and Bacteria Chapter 18

2. What is a virus? • Viruses: • Do not carry out photosynthesis or cellular respiration • Do not grow and develop • Can not replicate/reproduce on their own Are they living organisms?

3. Viral Structure • Genetic Material in the form of: • DNA • RNA • Capsid: outer protein coat • 4 common shapes • Polyhedral • Helical • Enveloped • Bacteriophage or phage

4. Bacteriophages • AKA phage • Is a virus that attacks bacteria

5. Polyhedral Viruses • Herpes virus • ds DNA • Adenovirus • ds DNA • Polio virus • Ss RNA

6. Helical Viruses • Tobacco Mosaic Virus • ss RNA

7. Enveloped Viruses • Contain an envelope made of • Lipids • Carbohydrates • Proteins • Influenza Virus • ss RNA • HIV • ss RNA

8. Viruses are Specific • Each virus is specialized • Most viruses are species-specific • Many viruses are also cell-specific

9. Viral Replication Cycles • Lytic Cycle • Kills the host cell • Lysogenic Cycle • Similar to lytic cycle but does not immediately result in the host cell’s death • Viral genetic material combines with host cell’s DNA • Provirus: Viral DNA that is integrated into host cell’s chromosome • Examples: HSV I & II, hepatitis B, and chicken pox

11. Lytic Cycle • A virus particle attaches to a host cell. • The particle releases its genetic instructions into the host cell. • The injected genetic material recruits the host cell's enzymes. • The enzymes make parts for more new virus particles. • The new particles assemble the parts into new viruses. • The new particles break free from the host cell.

12. Lysogenic Cycle

14. Retroviruses • Type of RNA virus that transcribes itself into ds DNA • The newly transcribed DNA inserts into host’s DNA • Ex: HIV

15. EXTRA CREDIT OPPORTUNITY • Write a 1 page paper about swine flu. • Be sure to include • A complete description of the virus that causes it (name, type, characteristics) • Symptoms and treatment (include names of specific drugs) • Prevention information (how can you avoid it) USE COMPLETE SENTENCES WORTH 20 POINTS – DUE FRIDAY INCLUDE REFERENCES

16. Prokaryotes • Unicellular organisms without membrane-bound organelles • 2 Kingdoms • Archaebacteria • Eubacteria

17. Archaebacteria • Live in harsh environments • 3 types • Methane-producers • Marshes • Lake sediments • Animal digestive tracts • Salt-dwellers • Dead Sea • Heat/Acid-dwellers • Deep ocean vents

18. Eubacteria: The Heterotrophs • Bacteria that obtain their nutrients from elsewhere • Some are parasites • Feed off of living organisms • Some are saprophytes • Feed on dead organisms • Feed on organic wastes (recyclers)

19. Eubacteria: Photosynthetic Autotrophs • Bacteria that convert solar energy into food • Cyanobacteria or blue-green algae • Found in aquatic environments • Composed of chains of independent cells

20. Eubacteria: Chemosythetic Autotrophs • Break down and release energy of inorganic compounds such as H2S • Important in converting atmospheric nitrogen into useable forms plants need

21. Structure

22. Identifying Bacteria: Gram Stain • Gram staining reflects differences in cell wall composition • Gram-positive bacteria stain blue- violet • Gram-negative bacteria stain pink

23. Identifying Bacteria: Shapes

24. Bacterial Reproduction • Asexually by binary fission • Very rapid at optimal conditions • can double every 20 minutes

25. Bacterial Reproduction • Sexually by conjugation

26. Common Bacterial Diseases

27. Beneficial Bacteria • Nitrogen Fixation N2→ NO2- + NO3- • Food • Yogurt • Cheese • Pickles • Sour cream • Sour kraut