Bio 101 Day 10

Bio 101 Day 10 - The Origin and Evolutionary History of...

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Unformatted text preview: The Origin and Evolutionary History of Life Chapter 21 Geologists believe that ancient earth provided the exact conditions necessary for chemical evolution-little or no free O2 (reducing conditions necessary to prevent oxidation of organic molecules, the building blocks of life)-Presence of chemical building blocks (water, minerals, gases)-Time to allow resulting accumulation and interaction and formation of organic molecules Chemical Evolution-Prebiotic soup hypothesis-organic molecules formed near Earth’s surface in “a prebiotic soup” of inorganic building blocks. Polymerization occurred spontaneously from monomers on hot rock or clay surfaces-I ron-sulfur world hypothesis-Polymerization of organic molecules produced at hydrothermal vents in deep ocean floor-Vents acted as products of energy-rich food including H-S and Methane Miller and Urey’s Experiment Could organic molecules form in a reducing atmosphere (early earth)? Gases in flask react; in one week a variety of simple organic compounds—amino acids, purines, pyrimidines etc accumulate-First step in the origin of life The Origin of Cells-Macromolecules-Polymerization from small organic molecules-Protobionts-Macromolecular Assemblages-A-biotically formed-Exhibit many functional and structural attributes of living cells, homeostasis, catalytic activity, etc.-Cells-Then arose from protobionts-Enclosed the information necessary for self-replication Microspheres-Protobiont is a form when water is added to abiotically formed polypeptides (liposomes when lipids present); selectively permeable; able to control osmotic swelling and shrinking; maintain homeostasis, and an electrical potential across surfaces “RNA World” Model-RNA as the first informational molecule to evolve-Self replicating and enzymatic molecule capable of catalyzing a number of biologically important reactions-Progression toward self-replication cell-Ribozyme (ribosome)-RNA makes a double stranded copy of itself-Evolution into DNA-Information transfer advantageous (DNA less reaction than RNA)-Natural selection of molecular level-resulted information sequence-DNA (non-catalytic) RNA Protein RNA Molecules Q. Can in vitro natural selection result in chemical evolution of catalysts, and could these...
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Bio 101 Day 10 - The Origin and Evolutionary History of...

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