Chapter 27 Prokaryotes Bacteria on the point of a pin

1. Chapter 27 Prokaryotes Bacteria on the point of a pin

2. Extreme Thermophiles

3. The Three Domains of Life

4. Streptococcus strepto=chain coccus=spherical

5. Bacilli=rod-shaped

6. Spirilla=helical includes spirochetes

7. Largest known prokaryote

8. Another large prokaryote paramecium Prokaryotes vary in size from 0.2µ--750µ

9. Evolution of Prokaryotic Metabolism • The Origin of Glycolysis– First prokaryotes 3.5 billion years ago, probably anaerobic chemoheterotrophs. They absorbed organic compounds and used glycolysis (fermentation) to produce ATP in an atmosphere without oxygen 2. The Origin of Electron Transport Chains and Chemiosmosis– The first proton pumps were probably for pH regulation. Later some bacteria used the oxidation of organic compounds to pump H+’s to save ATP and developed the first Electron Transport Chains. Some got so good at transporting H+’s that they could actually develop a gradient and use the influx to drive the production of ATP.

10. 3. The Origin of Photosynthesis– The first light absorbing pigments probably provided protection by absorbing UV light. Bacteriorhodopsin in extreme halophiles uses light energy to pump H+’s out of the cell and produce a gradient which is then used to produce ATP (Photosystem I) . Photoheterotrophs 4. Cyanobacteria, Photoautotrophs, Splitting H2O and Producing O2– Photosystem II evolved in cyanobacteria and they split water and released free oxygen. The oxygen was toxic to many organisms which became extinct. (First Great Extinction) 5. Origin of Cellular Respiration– Some prokaryotes modified their photosynthetic ETC’s to reduce the level of toxic O2. The purple non-sulfur bacteria still use their ETC’s for both photosynthesis and respiration. Eventually some bacteria used O2 to pull electrons through proton pumps and aerobic respiration began. aerobic chemoheterotrophs

11. Cell Walls All the proteobacteria and the eubacteria have peptidoglycan cell walls. Archaebacteria have a different type of cell wall. Cell walls protect bacteria from cytolysis in hypotonic solutions but can not protect them from plasmolysis in hypertonic solutions. Mycoplasmas without cell walls are susceptible to both. Penicillin denatures (noncompetitive inhibitor) the enzyme that bacteria use to form their cell walls and leaves them susceptible to cytolysis.

13. Gram-positive diplococcus

14. Gram-positive staphlococcus and Gram-negative diplobacillus

15. Bacillus with Pilli-used for conjugation, attachment to surfaces and snorkels for getting oxygen

16. Bacterial flagella rotate rather than bend

17. Bacteria with flagella

18. Bacteria with flagella

19. Bacteria with flagella

21. Infolding of the plasma membrane give these bacteria respiratory membranes and thylakoid-like membranes

22. Bacteria growing on agar in a petri dish

23. Mold cultures

24. An anthrax endospore

25. Endospores

28. ARCHAEA BACTERIA

29. Extreme halophiles in seawater evaporation ponds that are up to 20% salt; colors are from bacteriorhodopsin a photosynthetic pigment very similar to the pigment in our retinas

30. Hot springs with extreme thermophiles

31. Hydrogen Sulfide Metabolizing Chemoautotrophic Archaea found in sulfur springs

32. Eubacteria

33. The Proteobacteria are a major group (phylum) of bacteria. They include a wide variety of pathogens, such as Escherichia, Salmonella(rod-shaped Gram-negativeenterobacteria that causes typhoid fever and the foodborne illnesssalmonellosis , Vibrio(motile gram negative curved-rod shaped bacterium with a polar flagellum that causes cholera in humans.) , Helicobacter(stomach ulcers), and many other notable genera.[1] Others are free-living, and include many of the bacteria responsible for nitrogen fixation. The group is defined primarily in terms of ribosomal RNA (rRNA) sequences, and is named for the Greek god Proteus (also the name of a bacterial genus within the Proteobacteria), who could change his shape, because of the great diversity of forms found in this group.

34. All Proteobacteria are Gram-negative, with an outer membrane mainly composed of lipopolysaccharides. Many move about using flagella, but some are non-motile or rely on bacterial gliding. The last include the myxobacteria, a unique group of bacteria that can aggregate to form multicellular fruiting bodies. There is also a wide variety in the types of metabolism. Most members are facultatively or obligately anaerobic and heterotrophic, but there are numerous exceptions. A variety of genera, which are not closely related to each other, convert energy from light through photosynthesis. These are called purple bacteria, referring to their mostly reddish pigmentation.

35. Alpha Proteobacteria Alpha Proteobacteria Rocky Mountain Spotted Fever Ti plasmid Symbiosis with Legumes

36. Alpha Proteobacteria

37. Fruiting bodies of myxobacteria

38. Helicobacter pylori causes stomach ulcers

39. The Rickettsia are Gram-negative, obligate intracellular bacteria that infect mammals and arthropods. R. prowazekii is the agent of epidemic typhus. During World War I, approximately 3 million deaths resulted from infection by this bacterium. In World War II, the numbers were similar. This agent is carried by the human louse; therefore, disease is a consequence of overcrowding and poor hygiene. Rocky Mountain spotted fever and Q fever remain relatively common.

40. Rhizobium

41. Streptomycetes-soil bacteria that produces an antibiotic

42. Sulfur bacteria that split H2S in photosynthesis

43. Cyanobacteria with heterocysts-specialized cells with the enzymes for nitrogen fixation

44. Another Cyanobacteria

45. Another Cyanobacteria

46. Another Cyanobacteria

47. Cyanobacteria

48. Algae Blooms

49. Bull's-eye rash of a person with Lyme disease Spirochete that causes Lyme disease

50. Bull's-eye rash of a person with Lyme disease