LEC 24 Regulating Protein Synthesis -- Eukaryotes - ORIGIN...

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ORIGIN OF CELLULARITY AND CELLULARDIVERSITY
Last impact heating~3500Geological stratigraphy,together with radioactivedating, show thesequence of events inthe history of the Earth.Note the entry for“cyanobacteria” and“stromatolites” only onebillion years after theformation of the Earth.But what came before them?And how did cells becomemore complicated 1.5 Byears later?
Chemical experiments, initiated by Stanley Miller and Harold Urey,Showed that some biochemicals could be formed naturally(but not all--where did the rest come from?)Life starts with chemistry
Protobionts vs. surface layersWhat is important about a cell?How would you start, if you wanted to makea model of a cell?Hypothesis:Metabolism (energy, reproduction) needs away of concentrating intermediates.CellsAdsorptive surfaces
Protobionts: a steptoward living cells?In 1957, Sidney Fox demonstrated that dry mixtures of amino acidscould be encouraged to polymerize upon exposure to moderate heat.When the resulting polypeptides, or proteinoids, were dissolved in hotwater and the solution allowed to cool, they formed small sphericalshells about 2μm in diameter—microspheres. Under appropriateconditions, microspheres will bud new spheres at their surfaces.
Tiny compartments in mineral structures can shelter simplemolecules, while mineral surfaces can provide the scaffoldingon which those molecules assemble and grow. Beyond

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Term
Winter
Professor
GERHART
Tags
Bacteria, Radioactive Dating, key event, Prokaryote divergence Endosymbiosis, single primordial endosymbiosis, endosymbiosis Initial divergence

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