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12Alecture+8+small+grey - Life is a catalyst that catalyzes...

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Life’s Catalysts: The structure, func5on, and cost of proteins Chap. 8, Chap. 3.1 and 3.2 Progress of a reaction Energy of products (= people, plants…) Δ G Released energy Transition state A,B <-> C,D Energy of fuel, photons, chemicals of high G Life is a catalyst that catalyzes its own synthesis? Products are catalysts! Life uses energy from fuel and light to: turn simple materials into cell mass to pump nutrients in to move to do work. This is work accomplished by a huge number of individual catalysts (maybe 3500? for a bacterium ( E. coli )) These dictate all the metabolic capabilities we’ve talked about. Autotrophs, heterotrophs, fermenters, respirers, photosynthesizers, anaerobes, aerobes, differ in what catalysts they possess and therefore what reactions they can perform. The catalysts of modern life are mostly PROTEINS (ENZYMES) Other proteins are structural, pumps, “wires”, machines, regulators Structure is complicated Synthesis is complicated The underlying principles are quite simple Origins are hard to imagine When life originated, it must have used simpler catalysts. Look in modern life forms for clues to the past. Every reaction we’ve discussed has an enzyme …
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Why does life use a catalyst for every reaction? Why does life use a catalyst for every reaction? a) To make it go faster. b) To emphasize the rare useful reactions and avoid toxic alternatives. c) To tune pathways so rates are compatible. d) To optimize rates for ambient conditions . e) To allow it to compete by employing a specialized lifestyle. f) All of the above Why does life use a catalyst for every reaction? Answer(s) hidden here Questions For Today: 1. How do biological catalysts (proteins) make catalytic binding surfaces? 2. How do you measure catalytic ability of enzymes? 3. Why are proteins so expensive to make? Questions for another day: 1. How do you control catalyst behavior? 2. How does modern life make proteins? 3. How can life improve a catalyst? 4. How can life add a new catalyst? 5. How were the first protein catalysts made?
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How do enzymes do what they do? Proteins are made of amino acids, but enzymes often carry cofactors that participate in catalysis * These “coenzymes ” are simply substrates-­૒ they’re not enzymes. *
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If enzymes are all about “perfect fit” how does life build a shape to match the substrate? How does the cell generate these very particular 3-D shapes? How would we do it? Carve it? Sculpt it? Fold it? Life generates 3-­૒D shapes by folding…. …by folding of a 1-­૒D precursor Life generates 3D forms through folding of a linear form. Quite often, the linear forms simply folds itself up into the desired shape. Thus the code for the 3D form (the protein’s tertiary structure ) is hidden in the linear form (its primary structure ).
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