01:119:115 Lecture Notes - Lecture 2: Rna World, Abiogenesis, Alexander Oparin
31 Mar 2016
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Document Summary
Key events: origins of unicellular and mulicellular organisms and the colonizaion of land. First life developed from organic molecules formed spontaneously: fossil evidence of life 3. 5 billion years ago, abiogenesis hypothesis. Low free o2, e source, time, chemical building blocks. Not conductive to building blocks only forms two bonds (6 valence electrons) Earth~4. 6 billion years ago & life ~3. 5 billion years ago. Steps of abiogenesis: abiotic synthesis of monomers. 3: self-replication formation of organic macromolecules formation of protocells ( early cells ) 2 models: oparin-haldane hypothesis pre-biotic soup , proposed by a. i. Hypothesis: life formed near earth"s surface, conditions of early earth favored spontaneous formation of earth"s molecules. Test: 1953: miller- urey experiment (reducing atmosphere, found amino acids and other organic monomers) Recent developments: new data on early atmosphere neutral rather than reducing, experiment repeated under many conditions . Data suggests organic molecules would accumulate in oceans from organic soup . Hypothesis: organic molecules form and accumulate at hydrothermal vents.
