1. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains CHAPTER 26 Bacteria and Archaea: The Prokaryotic Domains

2. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Why Three Domains? Why Three Domains? General Biology of the Prokaryotes General Biology of the Prokaryotes in Their Environments Prokaryotes in Their Environments

3. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryote Phylogeny and Diversity Prokaryote Phylogeny and Diversity The Bacteria The Bacteria The Archaea The Archaea Chapter 26: Bacteria and Archaea: the Prokaryotic Domains

4. Why Three Domains? Living organisms can be divided into three domains: Bacteria, Archaea, and Eukarya.Living organisms can be divided into three domains: Bacteria, Archaea, and Eukarya. The prokaryotic Archaea and Bacteria differ from each other more radically than the Archaea from the Eukarya.The prokaryotic Archaea and Bacteria differ from each other more radically than the Archaea from the Eukarya.4

5. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Why Three Domains? Evolutionary relationships of the domains were revealed by rRNA sequences.Evolutionary relationships of the domains were revealed by rRNA sequences. Their common ancestor lived more than 3 billion years ago, that of the Archaea and Eukarya at least 2 billion years ago.Their common ancestor lived more than 3 billion years ago, that of the Archaea and Eukarya at least 2 billion years ago. Review Figure 26.2 and Table 26.1 26.226.126.226.15

6. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.2 figure 26-02.jpg

7. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Table 26.1 table 26-01.jpg

8. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes The prokaryotes are the most numerous organisms on Earth,occupying an enormous variety of habitats.The prokaryotes are the most numerous organisms on Earth,occupying an enormous variety of habitats.8

9. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Most prokaryotes are cocci, bacilli, or spiral forms. Some link together to form associations, but very few are truly multicellular.Most prokaryotes are cocci, bacilli, or spiral forms. Some link together to form associations, but very few are truly multicellular.9

10. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Prokaryotes lack nuclei, membrane-enclosed organelles, and cytoskeletons.Prokaryotes lack nuclei, membrane-enclosed organelles, and cytoskeletons. Their chromosomes are circular.Their chromosomes are circular. They often contain plasmids.They often contain plasmids. Some contain internal membrane systems.Some contain internal membrane systems.10

11. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Many prokaryotes move by means of flagella, gas vesicles, or gliding mechanisms.Many prokaryotes move by means of flagella, gas vesicles, or gliding mechanisms. Prokaryotic flagella rotate.Prokaryotic flagella rotate.11

12. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Prokaryotic cell walls differ from those of eukaryotes.Prokaryotic cell walls differ from those of eukaryotes. Bacterial cell walls generally contain peptidoglycan.Bacterial cell walls generally contain peptidoglycan. Differences in peptidoglycan content result in different reactions to the Gram stain.Differences in peptidoglycan content result in different reactions to the Gram stain. Review Figure 26.7 26.7 12

13. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.7 figure 26-07.jpg

14. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Prokaryotes reproduce asexually by fission, but also exchange genetic information.Prokaryotes reproduce asexually by fission, but also exchange genetic information.14

15. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains General Biology of the Prokaryotes Prokaryotes’ metabolic pathways and nutritional modes include obligate and facultative anaerobes, and obligate aerobes.Prokaryotes’ metabolic pathways and nutritional modes include obligate and facultative anaerobes, and obligate aerobes. Nutritional types include photoautotrophs, photoheterotrophs, chemoautotrophs, and chemoheterotrophs.Nutritional types include photoautotrophs, photoheterotrophs, chemoautotrophs, and chemoheterotrophs. Some base energy metabolism on nitrogen- or sulfur-containing ions.Some base energy metabolism on nitrogen- or sulfur-containing ions. Review Figure 26.8 and Table 26.2 26.826.226.826.215

16. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.8 figure 26-08.jpg

17. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Table 26.2 table 26-02.jpg

18. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryotes in Their Environments Some prokaryotes play key roles in global nitrogen and sulfur cycles.Some prokaryotes play key roles in global nitrogen and sulfur cycles. Nitrogen fixers, nitrifiers, and denitrifiers do so in the nitrogen cycle. Nitrogen fixers, nitrifiers, and denitrifiers do so in the nitrogen cycle. Review Figure 26.10 26.10 18

19. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.10 figure 26-10.jpg

20. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryotes in Their Environments Photosynthesis by cyanobacteria generated the oxygen gas that permitted the evolution of aerobic respiration and the appearance of present-day eukaryotes.Photosynthesis by cyanobacteria generated the oxygen gas that permitted the evolution of aerobic respiration and the appearance of present-day eukaryotes.20

21. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryotes in Their Environments Many prokaryotes live in or on other organisms, with neutral, beneficial, or harmful effects.Many prokaryotes live in or on other organisms, with neutral, beneficial, or harmful effects.21

22. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryotes in Their Environments A minority of bacteria are pathogens. Some produce endotoxins, which are rarely fatal; others produce often highly toxic exotoxins.A minority of bacteria are pathogens. Some produce endotoxins, which are rarely fatal; others produce often highly toxic exotoxins.22

23. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryote Phylogeny and Diversity Phylogenetic classification of prokaryotes is based on rRNA sequences and other molecular evidence.Phylogenetic classification of prokaryotes is based on rRNA sequences and other molecular evidence.23

24. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryote Phylogeny and Diversity Lateral gene transfer among prokaryotes makes it difficult to infer prokaryote phylogeny.Lateral gene transfer among prokaryotes makes it difficult to infer prokaryote phylogeny.24

25. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Prokaryote Phylogeny and Diversity Evolution can proceed rapidly in prokaryotes because they are haploid and can multiply rapidly.Evolution can proceed rapidly in prokaryotes because they are haploid and can multiply rapidly.25

26. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria There are far more known bacteria than archaea.There are far more known bacteria than archaea. One phylogenetic classification of the domain Bacteria groups them into over a dozen groups.One phylogenetic classification of the domain Bacteria groups them into over a dozen groups.26

27. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria The most ancient bacteria, like the most ancient archaea, may be thermophiles, suggesting that life originated in a hot environment.The most ancient bacteria, like the most ancient archaea, may be thermophiles, suggesting that life originated in a hot environment.27

28. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria All four nutritional types occur in the Proteobacteria.All four nutritional types occur in the Proteobacteria. Metabolism in different proteobacteria groups has evolved along different lines.Metabolism in different proteobacteria groups has evolved along different lines. Review Figure 26.12 26.12 28

29. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.12 figure 26-12.jpg

30. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria Cyanobacteria, unlike other bacteria, photosynthesize using the same pathways plants use.Cyanobacteria, unlike other bacteria, photosynthesize using the same pathways plants use. Many fix nitrogen.Many fix nitrogen.30

31. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria Spirochetes move by means of axial filaments.Spirochetes move by means of axial filaments.31

32. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria Chlamydias are tiny parasites that live within the cells of other organisms.Chlamydias are tiny parasites that live within the cells of other organisms.32

33. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria Firmicutes are diverse; some produce endospores, resting structures resistant to harsh conditions.Firmicutes are diverse; some produce endospores, resting structures resistant to harsh conditions. Some actinomycetes produce important antibiotics.Some actinomycetes produce important antibiotics. Actinomycetes grow as branching filaments.Actinomycetes grow as branching filaments.33

34. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Bacteria Mycoplasmas, the tiniest living things, lack conventional cell walls and have very small genomes.Mycoplasmas, the tiniest living things, lack conventional cell walls and have very small genomes.34

35. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea Archaea cell walls lack peptidoglycan, and their membrane lipids contain branched long-chain hydrocarbons connected to glycerol by ether linkages.Archaea cell walls lack peptidoglycan, and their membrane lipids contain branched long-chain hydrocarbons connected to glycerol by ether linkages. Review Figure 26.22 26.22 35

36. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains Figure 26.22 figure 26-22.jpg

37. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea The domain Archaea can be divided into two kingdoms:The domain Archaea can be divided into two kingdoms:  Crenarchaeota  Euryarchaeota. 37

38. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea Crenarchaeota are heat-loving and often acid-loving archaea.Crenarchaeota are heat-loving and often acid-loving archaea.38

39. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea Methanogens produce methane by reducing carbon dioxide.Methanogens produce methane by reducing carbon dioxide. Some live in the guts of herbivorous animals; some in high-temperature environments on the ocean floor.Some live in the guts of herbivorous animals; some in high-temperature environments on the ocean floor.39

40. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea Extreme halophiles are salt lovers that lend a pinkish color to salty environments; some grow in extremely alkaline environments.Extreme halophiles are salt lovers that lend a pinkish color to salty environments; some grow in extremely alkaline environments.40

41. Chapter 26: Bacteria and Archaea: the Prokaryotic Domains The Archaea Archaea of the genus Thermoplasma lack cell walls, are thermophilic and acidophilic, and have a tiny genome (1,100,000 base pairs).Archaea of the genus Thermoplasma lack cell walls, are thermophilic and acidophilic, and have a tiny genome (1,100,000 base pairs).41