Bio153_lecture2_originoflife_sv - Origin of Life and...

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Origin of Life and Ordering Diversity How Did Life Get Started? Origin of Life on Earth Key steps: Stage 1. synthesis of organic molecules: Stage 2. polymerization of macromolecules Stage 3. formation of membranes Stage 4. evolution of cellular properties Oparin-Haldane Hypothesis (1920s) Organic molecules (amino acids, sugars, nucleotides) essential to the formation of life could have been made in the absence of life - Spontaneous appearance of organic molecules produced a “primordial soup” that gave rise to living cells Reducing Atmosphere Hypothesis (1950s) Atmosphere contained - H 2 -N H 3 -C H 4 + volcanic gases (mostly CO 2 , N 2 , and H 2 O) Ancient earth - lack of ? Reducing Atmosphere Hypothesis - simple molecules of ancient earth participated in chemical reactions that produced complex molecules - chemical reactions require energy Why are these particular molecules of ancient earth essential to chemical evolution?
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Redox Reactions reduction-oxidation reactions • oxidation: • reduction: Redox Reactions Involve a Transfer of Electrons Chemical Evolution Hypothesis Early Origin-of-Life: Miller-Urey Experiments Chemical Evolution Hypothesis Simple molecules containing C, H, O, N react to form molecules with reduced carbon atoms, which then react to form organic compounds with C-C bonds; further reactions produce amino acids, sugars, etc. Extraterrestrial Hypothesis
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This note was uploaded on 02/01/2012 for the course BIOLOGY 153 taught by Professor Dr.arts during the Fall '10 term at University of Toronto- Toronto.

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Bio153_lecture2_originoflife_sv - Origin of Life and...

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