BB lecture 9-24-08 life origin & prokaryotes

BB lecture 9-24-08 life origin & prokaryotes -...

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Unformatted text preview: Chapter 25 (pp. 507-512) Early Life on Earth Learning objectives: Know the sequence of the chemical evolution hypothesis Describe the design and the significance of the Miller-Urey experiment Explain how organic polymers could have formed in early Earth prior to the existence of enzymes. Terms to know include: Oparin-Haldane hypothesis, abiotic synthesis, protobionts, ribozymes, RNA world, relative age/absolute age of fossils Chapter 27 [pp.556-560, 564,565] The Prokaryotes Draw/compare Gram-positive bacteria and Gram-negative bacteria cell walls. Describe the nutritional types of cells (regarding carbon and energy sources) Terms to know includepeptidoglycan, Gram-positive, Gram-negative, lipopolysaccharide, obligate aerobes, facultative anaerobes, obligate anaerobes Fig. 25-7 Animals Colonization of land P a l e o z o i c M e s o- z o i c Humans Ceno- zoic Origin of solar system and Earth Prokaryotes Proterozoic Archaean B i l l i o n s o f y e a r s a g o 1 4 3 2 Multicellular eukaryotes Single-celled eukaryotes Atmospheric oxygen Earth starts here (~4.5 bya) How did life begin..? Early Earth Origin of Life a hypothesis Four stages: 1. Abiotic synthesis of organic monomers (e.g., amino acids) 2. Abiotic synthesis of polymers (e.g., polypeptides) 3. Protobionts (membranous enclosures) 4. Self- replicating molecules (RNA first type?) The Oparin-Haldane Hypothesis Aleksandr Oparin (1924) and John Haldane (1929) independently suggested that: if the primitive atmosphere was reducing (as opposed to oxygen-rich), and if there was an appropriate supply of energy, such as lightning or ultraviolet light, then a wide range of organic compounds might be synthesized. Early Earth Conditions supposed by Oparin, Haldane...
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BB lecture 9-24-08 life origin & prokaryotes -...

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