Lecture - Oct 5

Lecture - Oct 5 - Chapter 21 Geologists believe that...

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Chapter 21 Geologists believe that ancient earth provided the exact conditions necessary for chemical evolution. - Little or no O 2 (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 Early Earth – very hostile, inhospitable; Chemical evolution - Prebiotic soup hypothesis o 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. - Ion-sulfur world hypothesis o Polymerization of organic molecules produced at hydrothermal vents in deep ocean floor o Vents acted as producers of energy-rich food including H 2 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 origin of life (new experts have provided evidence of NA) The Origin of Cells - Macromolecules o Polymerization from small organic molecules
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- Protobionts o Macromolecular assemblages o A-biotically formed o Exhibit many functional and structural attributes of living cells; homeostasis, o catapycatalytic activity etc - Cells o Then arose from protobionts o Enclosed the information necessary for self-replication Microspheres (fig) “RNA World” Model - RNA as the first informational molecule to evolve: o Self replicating and enzymatic molecule capable of catalyzing a number of biologically important reactions o Progression toward self-replicating cell o Ribozyme (ribosome) - RNA makes a double stranded copy of itself o Evolution into DNA o Information transfer advantageous (DNA less reactive than RNA) - Natural selection at molecular level: o Resulted in informational sequence o DNA (non catalytic) RNA protein RNA Molecules Q: Can in vitro natural selection result in chemical evolution of catalysts, and could these molecules have catalyzed the many different reaction necessary for life?
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Hypothesis: self-replicating RNA molecules can evolve and become more efficient catalysts. A: After selection, amplification and mutation, the final group of RNA molecules is the most efficient at catalyzing the chemical reaction selected for. . The First Cells
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This note was uploaded on 11/03/2009 for the course BIO 01-119-10 taught by Professor D'arville during the Fall '09 term at Rutgers.

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Lecture - Oct 5 - Chapter 21 Geologists believe that...

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