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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh Edition Solomon Berg Martin Chapter 20 The Origin and Evolutionary History of Life
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Conditions on early Earth Age of Earth is ~4.6 billion years Atmosphere had little free O 2 –Included CO 2, H 2 O, CO, H 2, N 2 –Maybe also NH 3, H 2 S, CH 4
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Requirements for chemical evolution to produce life Absence of oxygen Energy Chemical building blocks Sufficient time
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Prebiotic soup hypothesis Molecules formed near the Earths surface Sugars, nucleotides, amino acids formed spontaneously
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Miller-Urey experiment
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Iron-sulfur world hypothesis Organic molecules formed at hydrothermal vents on the ocean floor Laboratory simulations show catalyst effects of iron and nickel sulfides
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Origin of cells Spontaneous assembly of small organic molecules into macromolecules Protobionts similar to cells –Binary fission –Homeostasis –Catalytic activity
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Microspheres – a type of protobiont
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Microspheres Formed from water and polypeptides Electric gradient on surface Selective permeability
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life RNA world Self-replicating RNA molecules Function as both enzyme and substrate for replication –Ribozyme is enzymatic RNA First step in evolution of the DNA / RNA / protein system
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Directed evolution Large pool of RNA molecules with different sequences Selected for ability to catalyze a reaction Amplify / mutate / repeat
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Directed evolution
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life In the RNA world, ribozymes catalyzed protein synthesis DNA formed from double strands of RNA DNA more stable than RNA
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life The first cells Heterotrophs that feed on organic molecules Anaerobic fermentation process to obtain energy
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Autotrophs Selected after organic molecule food stock became scarce Photosynthetic production of organic molecules Cyanobacteria split water molecules and released oxygen
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Aerobes More efficient energy production using oxygen respiration Significant oxygen in the atmosphere by 2 bya
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Formation of the ozone layer Ultraviolet radiation forms O 3 from O 2 in the upper atmosphere Prevents UV from reaching Earth Decreased mutagenesis Enabled organisms to live in surface waters and on land
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Ozone formation
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Eukaryotes arose from prokaryotes Endosymbiont theory –Mitochondria and chloroplasts derived from prokaryotes –Ingested but not digested –Reproduced along with host cell
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Endosymbiont theory
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Geological eras Paleozoic –543 mya - 251 mya Mesozoic –251 mya - 65 mya Cenozoic –65 mya - present
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Using a clock to represent biological time
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Precambrian time Before 543 mya Bacteria Protists Fungi Simple multicellular animals
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Cambrian explosion All animal phyla established Many new body plans Bizarre, extinct phyla
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Ordovician period Shallow seas covered land Cephalopods Coral reefs Jawless fishes
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Silurian period Jawed fishes Terrestrial plants Air-breathing animals
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Devonian period Bony fishes Amphibians Wingless insects All major plant groups except for flowering plants established
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Carboniferous period Swamp forests Reptiles Winged insects
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Carboniferous forest
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Permian period Therapsids –Reptilian ancestors of mammals Seed plants dominant Ended the Paleozoic with the greatest mass extinction –90% of marine species –70% of land vertebrates
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Mesozoic Era
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Triassic period Thecodonts –Ancestors of dinosaurs and birds Pleiosaurs and ichthyosaurs Pterodonts First mammals –Small insectivores
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Jurassic and Cretaceous periods Saurischians –Ancestors of lizards Ornithischians –Ancestors of birds Ended with mass extinction caused by a meteorite impact
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Saurischians
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Ornithischians
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Cenozoic Era
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Copyright © 2005 Brooks/Cole Thomson Learning Biology, Seventh EditionCHAPTER 20 The Origin and Evolutionary History of Life Tertiary period Diversification of flowering plants, birds, insects, mammals Quaternary period Genus Homo Large mammals
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