Chapter 25 - C hapter 25: The H istory of L ife on Ea r th...

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Chapter 25: The History of Life on Earth Concept 25.1: Conditions on early earth made the origin of life possible: 1. The abiotic synthesis of organic molecules (amino acids and nucleotides) 2. The joining of these molecules into macromolecules (proteins and nucleic acids) 3. The packaging of these molecules into “protobionts” 4. The origin of self-replicating molecules that eventually made inheritance possible Concept 25.2: The fossil record documents the history of life. How fossils are dated: Sedimentary strata reveal the relative ages of fossils. Radiometric dating, which is based on the decay of radioactive isotopes. The rate of decay is expressed by the half-life. Magnetism of rocks Fossil records show how new groups of organisms gradually arose from a previously existing group. Concept 25.3: The geologic record 4.6 billion years ago: origin of solar system and Earth 3.5 billion years ago: oldest fossils of prokaryotes appear (stromatolites) 2.7 billion to 2.2 billion years ago: oxygen revolution caused by cyanobacteria
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This note was uploaded on 01/25/2011 for the course BIO 1510 taught by Professor Unknown during the Spring '07 term at Georgia Institute of Technology.

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Chapter 25 - C hapter 25: The H istory of L ife on Ea r th...

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