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Origin of Life and Prokaryotes

Origin of Life and Prokaryotes. BIOL 1407. Early Earth. 4.6 billion years ago (bya) Early atmosphere: No free oxygen Primarily nitrogen and carbon dioxide High energy from lightning, UV radiation Photo Credit: Mount St. Helens, May 18, 1980, taken by Austin Post, USGS.

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Origin of Life and Prokaryotes

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  1. Origin of Life and Prokaryotes BIOL 1407

  2. Early Earth • 4.6 billion years ago (bya) • Early atmosphere: • No free oxygen • Primarily nitrogen and carbon dioxide • High energy from lightning, UV radiation • Photo Credit: Mount St. Helens, May 18, 1980, taken by Austin Post, USGS

  3. Conditions of Early Earth • Intense volcanic activity • Meteorite bombardment • Warm environment • Photo Credit: Courtesy of NASA @ http://origins.jpl.nasa.gov/habitable-planets/images/ra7in16-early-earth.jpg

  4. Earliest Evidence of Life • Oldest fossil organisms: photosynthetic cyanobacteria • Western Australia • 3.5 bya

  5. Fossil Stromatolites • Multiple layers of cyanobacteria • Secreted CaCO3  dome-shaped structures • First reefs

  6. Living Stromatolites • Shark Bay, Australia • Hypersaline • Few predators

  7. Fossil vs. Living Cyanobacteria

  8. Earliest Life • Single-celled organisms probably evolved before 3.9 bya • No 3.9 bya fossils • Photo Credit: Robert Simmon, 2008, NASA, Wikimedia Commons Jack Hills: Rock formation in Australia; rocks > 3.6 bya; 4.4 bya zircon crystal found in this formation

  9. Why No 3.9 BYA Fossils? • Few rocks date to 3.9 bya • Tiny unicellular fossils are hard to find • Photo Credit of Proterozoic Stromatolites: UNP, 2006, Wikimedia Commons

  10. Molecular Fossils • Chemical traces of biomolecules • 3.9 bya evidence of prokaryotic lipids • Photo Credit of Hopanoid Compound: MarcoTolo, 2006, Wikimedia Commons

  11. Abiogenesis • Origin of life from non-living components • Photo of Stanley Miller: NASA, 1999, Wikimedia Commons

  12. Four Steps of Abiogenesis • Step 1: Synthesis of organic monomers from inorganic molecules • Photo credit for amino acid, tryptophan: Boghog2, 2007, Wikimedia Commons

  13. Four Steps of Abiogenesis • Step 2: Organic Monomers  Organic Polymers • Catalysts? • Photo Credit for Kassinin: Edgar181, 2007, Wikimedia Commons

  14. Four Steps of Abiogenesis • Step 3: Protobionts form • Protobiont = Organic molecules surrounded by membrane-like structure

  15. Protobionts • Life-like properties: • Reproduce • Simple Metabolism • Membrane potentials

  16. Four Steps of Abiogenesis • Step 4: Heredity • Pass instructions to offspring • Controls protein synthesis • 1st genetic material: RNA? • Photo Credit of Hammerhead Ribozyme: William G. Scott, 2007, Wikimedia Commons

  17. RNA Self-Replication Photo Credit: Campbell, 1999

  18. DNA replaced RNA. Why? Picture Credit: Figure 17-3, 8th ed. Campbell, modified from original

  19. Where did Abiogenesis Occur? • Hypotheses: • Hydrothermal vents • Tide pools • Panspermia: from outer space • Photo Credit for Black Smoker: NOAA, 2006, Wikimedia Commons

  20. Evolution of Prokaryotes? Photo Credit of Lassen Volcanic National Park Hot Springs: Walter Siegmund, 2005, Wikimedia Commons

  21. Oxygen Revolution • Oxygen accumulated • Most anaerobes died • Some survived in anaerobic habitats • Photograph: Banded iron formations that indicate free oxygen in oceans (2.7 bya)

  22. Oxygen Revolution • Oxygen  Evolution of aerobic respiration • Increased ATP production  More energy • Photo Credit of Bacillus cereus on blood agar: CDC, 2006, Wikimedia Commons

  23. Prokaryotic Cells • Review • Prokaryotic cell structure from BIOL 1406 • Cell wall present

  24. Prokaryotic Cells • Review • Circular chromosome • Plasmids

  25. Prokaryotic Cells • Review • Reproduction (binary fission) • Membrane transport • Gases • Water • Wastes • Ions • Photo: Dr. Vincent A. Fischetti, Laboratory of Bacterial Pathogenesis and Immunology, Rockefeller University, Courtesy of NOAA

  26. Prokaryotic Cell Shapes

  27. Prokaryotic Nutrition • Heterotrophs • Autotrophs

  28. Heterotrophs • Energy from: • Organic matter • Chemoheterotroph • Light • Photoheterotroph

  29. Autotrophs • Energy from: • Inorganic matter • Chemoautotroph • Light • Photoautotroph

  30. Photoautotrophs • Photoautotrophs can be: • Non-oxygenic • Oxygenic Photo: Cyanobacteria that uses oxygenic photosynthesis

  31. Prokaryotic Domains • Domain Bacteria • Domain Archaea

  32. Domain Bacteria • Prokaryote • Cell wall contains peptidoglycan • Circular chromosome • No histones • Photo: Beggiatoa, a sulfur bacterium. Granules contain elemental sulfur produced by the cell’s metabolism.

  33. Domain Bacteria • Five main clades of Bacteria

  34. Clade Proteobacteria

  35. Other Bacterial Clades

  36. Domain Archaea • Prokaryote • No peptidoglycan in cell wall • Circular chromosome • Histones • Photo: Halobacterium, a salt-loving (halophile) archaean. Courtesy of NASA.

  37. Archaeans • Most known archaeans are extremophiles • Picture Credit of Hydrothermal Vent Archeans, Extreme Thermophiles: Courtesy of NOAA

  38. Left: Owen Lake, California Right: Halobacterium Picture Credit: Courtesy of NASA Halophiles

  39. Left: Hot Springs, Yellowstone Right: Nevada Geyser Extreme Thermophiles

  40. Left: Methanopyrus kandleri, 2006, PMPoon, Wikimedia Commons Right: Methanothermobacter, Tashiror, 2006, Wikimedia Commons Methanogens

  41. Left: Sulfolobus, Xiaoya Xiang,2007, Wikimedia Commons Right: Acid mine drainage, Carol Stroker, 2005, NASA Wikimedia Commons Acidophiles

  42. Archaeans in “Normal Environments” • Oceans, soils,freshwater Photo Credit of Worldwide View of Plankton, 1998-2004: NASA, Wikimedia Commons Note: Archaeans are an important part of plankton. Up to 20% of world’s biomass may be archaeans.

  43. Domain Archaea is Sister Taxon to Domain Eukarya

  44. Lateral Gene Transfer • Difficult to find universal ancestor

  45. The End Unless otherwise specified, all images in this presentation came from: Campbell, et al. 2008. Biology, 8th ed. Pearson Benjamin Cummings.

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