2. Anthrax Bacillus anthracis Cutaneous anthrax

3. Microbial Diversity Chapt. 27 – Prokaryotes and the Origins of Metabolic Diversity & Chapt. 28 – The Origins of Eukaryotic Diversity

4. What are microbes? Single-celled organisms and some non-cellular parasites

5. Kinds of microbes Non-cellular, parasitic molecules Viruses Viroids Prions Prokaryotes Domain Bacteria Domain Archaea Eukaryotes Several Kingdoms in Domain Eukarya

6. Nonliving parasitic molecules HIV Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV

7. Nonliving parasitic molecules Viroids Short, single strand of RNA w/o protein coat Primarily infect plants Viruses Single or double stranded RNA or DNA with a protein coat Common cold, Ebola, HIV Prions Protein particles w/o genetic material Kuru, mad cow, chronic wasting disease

8. Kinds of microbes Non-cellular, parasitic molecules Viruses Viroids Prions Prokaryotes Domain Bacteria Domain Archaea Eukaryotes Several Kingdoms in Domain Eukarya

9. Carl Woese’s 3 Domains of Life Based primarily on genetic sequence data;e.g., small subunit ribosomal RNA – present in all organisms See Fig. 27.12

10. Prokaryotes Carl Woese’s 3 Domains of Life Eukaryotes NOTE: “Microbes” and “Prokaryotes” are not taxonomic categories See Fig. 27.12

11. Prokaryotes Carl Woese’s 3 Domains of Life Eukaryotes NOTE: Eukarya & Archaea are more closely related than either is to Bacteria See Fig. 27.12

12. Prokaryotes Carl Woese’s 3 Domains of Life Eukaryotes Even so, Archaea & Bacteria share more structural & functional properties than either does with Eukarya See Fig. 27.12

13. Microbes are microscopic, but very diverse & extremely abundant Bacteria on the tip of a pin

14. Relative sizes of microbes

15. Prokaryotes Domains Bacteria & Archaea Simple cells – with no nucleus or membrane-bound organelles

16. Prokaryotes Domains Bacteria & Archaea Simple cells – with no nucleus or membrane-bound organelles First organisms on Earth – at least 3 billion years ago

17. The oldest known fossilsCyanobacteria > 3 billion years old

18. Prokaryotes Domains Bacteria & Archaea Simple cells – with no nucleus or membrane-bound organelles First organisms on Earth – at least 3 billion years ago Distributed globally – including many extremophiles

19. Extreme Thermophiles“Heat-loving” Archaea

20. Extreme Halophiles“Salt-loving” Archaea pink color due to halophiles Australian Salt Lake

21. MethanogensMethane-generating Archaea Occur in oxygen-free habitats E.g., swamp mud, guts of ruminant animals

22. Ice Bacteria & Archaea

23. Cave Bacteria Sometimes reaching acidity of pH 0.5

24. Prokaryotes Domains Bacteria & Archaea Simple cells – with no nucleus or organelles First organisms on Earth – at least 3 billion years ago Distributed globally – including many extremophiles Nutrition – autotrophs & heterotrophs

25. Prokaryote Nutrition All organisms require a source of energy & carbon Autotrophs can obtain all their C from CO2

26. Prokaryote Nutrition All organisms require a source of energy & carbon Heterotrophs require at least one organic nutrient, e.g., glucose

27. Prokaryote Nutrition All organisms require a source of energy & carbon Phototrophs obtain their energy from the sun

28. Prokaryote Nutrition All organisms require a source of energy & carbon Chemotrophs obtain their energy from chemical compounds

29. Bacteria Systematic / phylogenetic relationships among bacteria are based on genetic data, but structural properties are indispensable for identifying them Structure

30. Bacteria Cell wall – unique, peptidoglycan Peptidoglycan - structural polysaccharides (sugars) cross-linked by peptides (chains of amino acids) Structure

31. Two biochemical groups of bacteria: outer membrane peptidoglycan

32. Two biochemical groups of bacteria: outer membrane peptidoglycan will stain will not stain Gram positive bacteria Gram negative bacteria

33. Gram stainDistinguishes different cell wall types Gram positive Staphylococcus aureus Gram negative Escherichia coli

34. 3 common bacterial shapes: Cocci- spheres Bacilli- rods Spirilli- spirals

35. Bacteria Structure Cell wall – unique, peptidoglycan Capsules or slime layer

36. E.g., slime layer allows bacteria to cling to tooth enamel or other substrates

37. Bacteria Structure Cell wall – unique, peptidoglycan Capsules or slime layer Pili & Flagella

38. Pili (singular: pilus) Protein filaments that attach bacteria to other cells & substrates pili

39. flagella Some prokaryotes have flagella(singular: flagellum) Used for locomotion

40. Base of a bacterial flagellum… …the only known wheel in nature 50 nm Fig. 27.6

41. What is “taxis”? Motility allows some bacteria to move towards or away from stimuli Phototaxis Chemotaxis Magnetotaxis

42. Bacteria Structure Cell wall – unique, peptidoglycan Capsules or slime layer Pili & Flagella Circular DNA molecule & plasmids

43. Bacteria Reproduction Asexual, through binary fission

44. Binary fission Chromosome Plasma membrane Daughter cells are identical copies (3) (1) (2) (4) (5) (6) Neither mitosis nor meiosis occurs in prokaryotes

45. Binary fission E. coli DNA cell wall

46. Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes

47. Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes Horizontal transfer of genetic material Transformation Uptake of genetic material from the environment

48. Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes Horizontal transfer of genetic material Transformation Transduction Transfer of genetic material between prokaryotes by viruses

49. Bacteria Reproduction Asexual, through binary fission No true sexual reproduction, since neither mitosis nor meiosis exist in prokaryotes Horizontal transfer of genetic material Transformation Transduction Conjugation Direct transfer of genetic material from one prokaryote to another

50. Conjugation in E. coli Sex pilus connects cells and draws them together Conjugation tube then forms Sex pilus