Prokaryotes and the Origin of Metabolic Diversity

1. Prokaryotes and the Origin of Metabolic Diversity

2. Prokaryotes • Kingdom Monera • Cell wall composed of murein (peptidoglycan) • includes: • Actinomycetes • chemoautotrophic bacteria • cyanobacteria • endospore forming bacteria • enteric bacteria • mycoplasmas • myxobacteria • nitrogen fixing aerobic bacteria • phototrophic anaerobic bacteria • pseudomonads • rickettsias • chlamydias • spirochetes

3. Actinomycetes • Colonies of branching hyphae • reproduction - fragmentation of ends to form spores • organic litter of soil • Mycobacterium, Streptomyces

4. Chemoautotrophic Bacteria • Energy from oxidizing NH3, NO3-, H2S, S, and Fe+3 + CO2 • obligate aerobes • aerated soil • Nitrobactere, Nitrosomonas

5. Cyanobacteria • Photoautotrophs • chlorophyll a • phycobilins • nitrogen fixation • in heterocysts • Nostoc, Anabaena, • Oscillatoria

6. Endospore Forming Bacteria • Gram positive, flagellated rods • endospores • obligate anaerobes & aerobes • Bacillus, Clostridium

7. Enteric Bacteria • Gram negative • facultative anaerobes • intestinal tracts • natural • pathogenic • Escherichia, Salmonella,Vibrio

8. Mycoplasmas • Smallest of all cells (0.10-0.25 microns) • no cell walls • extracellular growth • saprobes and animal pathogens • Mycoplasma

9. Myxobacteria • Soil dwelling chemoheterotrophs • gliding movement • congregate into fruiting masses • Myxococcus

10. Nitrogen-Fixing Aerobic Bacteria • Free-living & mutualistic • important in nutrition of plants • nodules of legumes • Rhizobium

11. Phototrophic Anaerobic Bacteria • Do not release oxygen • strict anaerobes • ponds, lakes, ocean sediments • purple & green sulfur bacteria • Chromatium, Rhodospirillum

12. Pseudomonads • Nearly all aquatic and soil habitats • rod shaped, Gram negative, lophotrichous • chemoheterotrophs • Pseudomonas

13. Rickettsias and Chlamydias • Obligate intracellular parasites of animals • reduced Gram negative wall • Rickettsias alternate between arthropod and mammal hosts • Chlamydias contracted from other humans or birds • Rickettsia, Chlamydia

14. Spirochetes • Helical cells • corkscrew-like movement with internal flagella • free-living saprobes and parasites • Borrelia, Treponema

15. Bacterial Shapes • Three basic shapes • coccus • bacillus • spirillus • Variations in shapes • strepto- • staphlo- • sarcinae • diplo • tetrads • vibrio

18. External Structure • Flagella • parts • hook • flagellum proper • rings • s • m • l • p

19. L ring P ring S ring M ring

20. Flagellum • Arrangement • atrichous • monotrichous • peritrichous • lophotrichous • Composition • flagellin (protein) • -N-methyl lysine

21. Pilus • Functions • F pilus (sex pilus) • attachment site for bacteriophages • adherence • Spines • Gram (-) marine species • unknown function

22. Capsules • Composition • some have dextrans, levans, or celluloses • some have above in combination with muceins • uronic acid • Pathogenic species often encapsulated

23. Slime Layers • Gelatinous material on cell walls • Unorganized

24. Cell Walls • Functions • prevent rupture due to osmotic pressure • support for flagella • maintain shape of bacteria

25. Cell Walls • Composition • diaminopimelic acid (DPA) in those that lack lysine • teichloic acid (formed from N-acetylglucoasamine [NAG]) • muramic acid (from N-acetylmuramic acid [NAM]) • common amino acids • uncommon amino acids

28. Gram Stain

29. Bacterial Structure(Internal) • Cell Membrane • similar to fluid-mosaic model in eukaryotic cells

30. Cell Membrane • Functions • controls passage of nutrients & wastes • location of several cytochromes for photosynthesis and respiration • location of enzymes for cell wall synthesis • enzymes for electron transport system

31. Mesosomes • Mostly in Gram + • pocket-like • contain tubules or lamellae • Functions • cell wall synthesis • division of DNA • respiration • spore formation

32. Genetic Material • Circular DNA • Plasmids (DNA) • capable of independent replication • gives drug resistance • not essential for life

33. Ribosomes • 40% protein, 60% RNA • 90% of cell RNA is in ribosomes • 70s (Svedberg sedimentation coefficient)

34. Photosynthetic Apparatus • Tied to cell membrane • pigments stored in vesicles or thylakoids

35. Protoplasmic Inclusions • Non-membrane bound • Metachromatic granules (volutin) • stain red with aged methylene blue • functions • storage of inorganic phosphates • storage of food • Polysaccharide granules • starch and glycogen

36. Protoplasmic Inclusions • Membrane Bound • carboxysomes (fix CO2 in photosynthesis) • lipids • gas vacuoles • aquatic prokaryotes • functions • cell buoyancy • protect from uv radiation • regulate surface area/volume relationships • combination of above

37. Protoplasmic Inclusions • Spores • bacterial • endospores • exospores • cysts • conidia

38. Protoplasmic Inclusions • Spores • cyanobacteria • heterocysts • akinetes

39. Reproduction • Asexual • binary fission • Sexual • transformation • conjugation • transduction

49. Archaebacteria • Cell walls lack peptidoglycan • distinct lipid composition of cell membranes • RNA polymerase and ribosomal protein more eukaryotic-like • live in extreme environments • methanogens • halophiles • thermoacidophiles

50. Methanogens • H2 used to reduce CO2 to methane (CH4) • strict anaerobes • swamps and marshes • decomposers of sewerage • farmers use to convert garbage and dung to methane • inhabit guts of animals (termites, cows)