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Evolution of Life

Evolution of Life. Terminology for Life. PROKARYOTE - NO internal organelles or membrane-bound nucleus with chromosomes EUKARYOTE - HAVE internal organelles (chloroplasts & mitochondria) & membrane-bound nucleus with chromosomes . Terminology for Life.

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Evolution of Life

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  1. Evolution of Life

  2. Terminology for Life • PROKARYOTE - NO internal organelles or membrane-bound nucleus with chromosomes • EUKARYOTE - HAVE internal organelles (chloroplasts & mitochondria) & membrane-bound nucleus with chromosomes

  3. Terminology for Life • ANAEROBE - cannot survive in an environment with free O2 • AEROBE - can survive in an environment with free oxygen

  4. Terminology for Life • HETEROTROPH - cannot synthesize food • AUTOTROPH - can synthesize food by fixing Carbon • CHEMOSYNTHESIS - use chemical energy to fix Carbon • PHOTOSYNTHESIS - use sunlight to fix Carbon

  5. Attributes of Life • Self replication or ability to reproduce • Ability to sustain orderly internal chemical reactions - requires energy

  6. Essential components of life • Protein: strings of comparatively simple organic molecules • amino acids: building blocks of proteins act as building materials • nucleic acids: DNA and RNA assist in chemical reactions within the organism • Organic phosphorous compounds- serve to transform light or chemical fuel into the energy required for cell activities

  7. How did Life begin? • Miller Urey Experiment • Simulated Early Atmosphere • (water vapor, Hydrogen, Methane and Ammonia) • Energy from Lightning

  8. Archean Life • Miller and Urey • Produced amino acids found in proteins • Modeled primitive atmosphere • Added lightning • excluded oxygen • Amino acids found on meteorites

  9. Miller-Urey Results • Chemicals formed include: • all 20 amino acids, sugars, lipids, the purine and pyrimidine bases found in nucleic acids and ATP (when phosphate is also present). • Only worked with NO O2

  10. Miller-Urey Results • Coupled with this were the new important discoveries by astrophysicists of the presence of organic molecules in the interstellar medium and in meteorites. • Murchison Meteorite that fell in Australia in 1969 had the same amino acids as in the Miller-Urey experiment.

  11. FIRST AUTOTROPHS • CHEMOSYNTHETIC ANAEROBES • Used heat energy from MOR hot springs • Used the energy released from naturally occurring chemical reactions

  12. 1st PHOTOSYNTHETIC AUTOTROPHS • ANAEROBIC BACTERIA (PROBABLY) • like those now found only in restricted environments [anaerobic hot springs in Yellowstone Park] • 6 CO2 + 6 H2S + energy -> C6H12O6 + 6 S (no free O2)

  13. 1st PHOTOSYNTHETIC AUTOTROPHS • ANAEROBIC BACTERIA (PROBABLY) • As old as oldest continental crust (probably) • Carbon spheres in Isua Greenland rocks - 3.8 bya • Carbon isotopes are ~ -25‰

  14. 1st PHOTOSYNTHETIC AUTOTROPHS

  15. 2nd PHOTOSYNTHETIC AUTOTROPHS • Aerobic CYANOBACTERIA (blue-green algae) • 6 CO2 + 6 H2O + energy -> C6H12O6 + 6 O2 (lots of free O2)

  16. 2nd PHOTOSYNTHETIC AUTOTROPHS • O2 initially produced by cyanobacteria reacted chemically with previously dissolved (Fe+2) iron to form Banded Iron Formations (BIFs) • did not accumulate in the atmosphere

  17. 2nd PHOTOSYNTHETIC AUTOTROPHS • ~2 billion years ago the dissolved iron reservoir was exhausted & the atmosphere began accumulate O2 • ANAEROBIC ORGANISMS • Driven below the surface

  18. ARCHEAN FOSSIL RECORD • Archean fossils are not abundant. Two types: • Microfossils and Stromatolites • MICROFOSSILS • prokaryote bacteria & cyanobacteria only • Warrawonga group - 3.5-3.4 bya in W. Australia- • Filamentous Cyanobacteria • Fig Tree Group - 3.4 bya in SOUTH AFRICA) - • PRIMITIVE BACTERIA & UNICELLULAR CYANOBACTERIA

  19. Archean Life • Earth is best suited known planet • Conditions right by 4.2 B years • Western Australia organic compounds • 3.5 B years • Mars • Water flowed once • Life may have evolved separately

  20. Archean Life • South African cherts contain possible mold of prokaryotic cell • 3.4 B years • Oldest unquestionable life form • 3.2 B years old • Australia • Intertwined filaments

  21. Archean Life • Stromatolites • 3.2 Billion years • Suggest photosynthesis • Biomarkers for cyanobacteria • 2.7 Billion years

  22. Archean Life • Mid-ocean ridges • High heat • Chemosynthetic organisms • Hydrogen oxidation • 2H2 + O2 − > 2H2O + energy • Sulfur reduction • S + H2 − > H2S + energy • Methane production • CO2 + 4H2 − > CH4 + 2H2O + energy

  23. Archean Life • Ridges offer wide range of temperatures • Organic compounds readily dissolve in warm water • Protection from ultraviolet radiation • Abundant phosphorous • Contain metals • Contain clays

  24. Archean Life • Atmospheric Oxygen • Low concentrations early on • Later, O2 released through photosynthesis • Sink • Reservoir that grows so as to take up a chemical as it is produced • Early crust was sink for O2 • Pyrite (FeS2) transported but not oxidized

  25. Fossil BacteriaApex Chert, W. Australia. These are dated at 3.465 Ga.

  26. Fossil BacteriaSwaziland (South Africa)3. 5 Ga.

  27. Fossil BacteriaFilamentous Cyanobacteria, No. Australia (1.5 Ga)

  28. Fossil BacteriaBitter Springs Australia ~1 bya

  29. Fossil BacteriaBitter Springs Australia ~1 bya

  30. Precambrian filamentous cyanobacteria. Cyanobacteria (Nostocales) from the Bitter Springs Chert of Central Australia, 850 million years old. Optical photomicrographs showing well preserved Oscillatoriacean, Nostocacean and, possibly, Rivulariacean trichomes in petrographic thin sections of Black chert.

  31. Review of Life Events:Carbon Isotopes at 3.8 Gamicrofossil at 3.5 GaStromatolites at 3.2 Ga1st Eukaryotes 2.1 GaAcritarchs 1.6 GaEdiacaran Fauna 570 Ma

  32. ARCHEAN FOSSIL RECORD • STROMATOLITES - formed by photosynthetic cyanobacteria & presently are restricted to stressed environments; during the Precambrian occurred in many environments: • Possibly in WARRAWOONA GROUP (3.5-3.4 bya) • PONGOLA SUPERGROUP - 3.1-2.8 bya (SOUTHERN AFRICA) • Stromatolites are not abundant until Early Proterozoic

  33. STROMATOLITES - Shark Bay, Western Australia.These are not rocks, but growths of algae.

  34. STROMATOLITES - Shark Bay, Western Australia.

  35. STROMATOLITES - Shark Bay, Western Australia.Hamlin Pool.

  36. What are Stromatolites? • Stromatolites are laminated structures built mainly by cyanobacteria (sometimes known as blue-green bacteria or, less correctly, as blue-green algae). They are still found today. • They dominated the fossil record between about 2000 million and 1000 million years ago. Today, they are found mainly in saline lakes or hot spring environments, often in environmental niches that other organisms cannot tolerate. • The best example of living stromatolites is at Hamelin Pool, Shark Bay, Western Australia.

  37. What are Stromatolites? • The bacteria precipitate or trap and bind layers of sediment to make accretionary structures, which can be domes, conical or complexly branching. • They can range in size from smaller than a little finger to larger than a house. • Some branching stromatolites resemble modern corals.

  38. What are Stromatolites? Blow up of filaments trapping sediments

  39. What are Stromatolites?

  40. What are Stromatolites? Kona Dolomite (Michigan) 2.2 bya stromatolite fossil

  41. Precambrian columnar stromatolite from the Fig Tree Group, South Africa. Archean, 3.5 billion years old.

  42. Precambrian conical stromatolite from Australia, 3.5 billion years old.

  43. Proterozoic stromatolitic bioherm in the Belt Supergroup. Field photo showing weathered vertical section through a carbonate stromatolitic bioherm in the Belt Supergroup, 1.3 bya

  44. EVOLUTION OF EUKARYOTES IN THE EARLY PROTEROZOIC Organization of DNA into chromosomes in nucleus allowed development of sexual reproduction & the rate of organic evolution increased

  45. The Eukaryotic Cell

  46. EVOLUTION OF EUKARYOTES IN THE EARLY PROTEROZOIC Eukaryotes are thought to have developed from symbiotic relationship between previously-independent prokaryotes EUKARYOTES ARE LARGER THAN PROKARYOTES

  47. EVOLUTION OF EUKARYOTES IN THE EARLY PROTEROZOIC Eukaryotes did not evolve until the atmospheric O2 began to accumulate

  48. Evolution of Eukaryotes • Union of 2 prokaryotic cells • Mitochondrian • Allow cells to derive energy from their food by respiration • Evolved from 1 prokaryotic cell • Chloroplast • Site of photosynthesis • Protozoan consumed, retained cyanobacterial cell

  49. EVOLUTION OF EUKARYOTES The Endosymbiotic Hypothesis

  50. The Endosymbiotic Hypothesis It has been argued that mitochondria and plastids (and perhaps flagella) were once free-living bacteria that took up residence inside the cell of another organism, probably an Archea. The reason the eukaryotic cell is more complex is that it has fused the function of several formerly free-living organisms.

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