CHAPTER 16 The Origin and Evolution of Microbial Life: Prokaryotes and Protists

1. CHAPTER 16The Origin and Evolution of Microbial Life: Prokaryotes and Protists

2. 4.8 BYA - earth • The early atmosphere probably contained H2O, CO, CO2, N2, and possibly some CH4, but little or no O2 – reducing atmosphere Figure 16.1A

3. = 500 million years ago Earliest animals; diverse algae Earliest multicellular eukaryotes? Earliest eukaryotes Accumulation of atmospheric O2 from photosyntheticcyanobacteria Billions of years ago Oldest known prokaryotic fossils Origin of life? Figure 16.1C Formation of Earth

4. 2 Domains of prokaryotes Domain Archaea (Kingdom Archaebacteria) Evolved first • “extreme” bacteria • Probably gave rise to eukaryotes based on cell structure (chart pp. 323)

6. Domain Bacteria • More recent bacteria • Most of the bacteria we are familiar with • Contain helpful & harmful

7. Phyla classification • 9 major groups or phyla (5 in book) • P. Proteobacteria • P. Chlamydias • P. Spirochetes • P. Gram + • P. Cyanobacteria

8. Importance

9. classified by shape & clustering • SHAPES • Spheres • Rods • Curves & sprirals • Clustering • Strepto • Staphylo Figure 16.9A-C

10. Bacterial cell morphology

11. Bacterial Plaque

12. Morphology • Gram positive bacteria • Gram negative –

13. Nutrition & Niche • Heterotrophs (organic C) • Autotrophs (CO2 for C) • Photo- (use of sun for NRG) or chemo- (use of inorganic compounds for NRG)

14. Reproduction & Growth

15. conjugation

16. How did they ever evolve?? • mutations • Conjugation • Transduction • Transformation

17. How do they cause harm? • Exotoxins • Endotoxins • Toxins released when bacteria die • Enzyme destruction of tissue • Attachment of bacteria to cell, enzymes “digest” cell

18. suvivorship

19. Common bacterial Diseases

20. transmission

21. Control of Bacteria • Prevent entry to body • Antibiotics • Antibiotic resistance

23. Viruses … a little bit of left-over life…

24. What is a virus? • Non-living • Particle • Obligate intra-cellular parasites • Can only “live” and make more within a host

25. Harmful Virulent Temperate Helpful Transduction Breeding TMV and other viruses often destroy chlorophyll – unique coloration Effects of Viruses

26. Classified by… • Shape • Icosahedral, spherical, rod, lunar-lander • Genetic Material • DNA – makes mRNA & thus viral proteins OR • RNA – • Host they infect • The living world – plants, animals, bacteria

27. Structure • Protein coat surrounding a core of genetic material = • Viroid - • Prion - • Bacteriophage –

28. How they work • Must infect host cell - specificity • Take over the host’s genetic machinery • Vectored by • Can cause immediate harm or “wait” for the right time to become “active”

29. Lytic Cycle • Fast cycle, immediate harm • Absorbtion • Recognition of host • Entry • Often only the DNA/RNA • Replication • Many copies of viral genes made • Assembly of new viruses • Release to reinfect other cells • lyse

30. Lysogenic Cycle • Slow cycle with dormant or latent period • Absorbtion • Entry • Formation of prophage – • Replication without harm – host makes many copies of virus as it copies its own genetic info for mitosis • Stimulus –

31. HIV & the Lysogenic Cycle • HIV + vs. AIDS • Dormant phase of 8-10 years • When activated, so much virus is present, symptoms appear very rapidly • Affects T4 cells or the “white blood cell immunity army” • NO defence against other “invaders”

32. Control of Viruses • NO • Prevent entry to body • Prevent insect bites, boil water, heat food, clean, cover mouth, no unprotected sex • Stop attachment – • Stop entry to cell • Stop replication – induced mutations • Stop lysing • White blood cells and immunity