PowerPoint PresentationSlide 2Slide 3Slide 4Slide 5Slide 6Slide 7Slide 8Slide 9Slide 10Slide 11Slide 12Slide 13Slide 14Slide 15Slide 16Slide 17Slide 18Slide 19Slide 20Slide 21Slide 22Slide 23Slide 24Slide 25Slide 26Slide 27Slide 28Slide 29Slide 30Slide 31Slide 32Slide 33Slide 34Slide 35Slide 36Slide 37Slide 38Slide 39Slide 40Slide 41Slide 42Slide 43Chp.14 Principles of Bioenergetics Metabolism = the sum of all chemical reactions that take place in a cell or organism.Bioenergetics = the quantitative study ofthe energy transductions that occur inin living cells and the nature and functionof the chemical processes underlying thesetransductions.4 x 10 11metric tons of carbonare turned over in thebiosphere each year.Catabolic pathways generally converge. Anabolic pathways divergeSome pathways are cyclic.Voet & VoetFig. 15-1AMetabolic“Map”Acetyl-CoAplays centralroleFig 3-6 Page 57Acetyl-Coenzyme AOxidation of glucose 24 electronsGlucose + 6O2 6CO2 + 6H2O G’o = -686 kcal/moleGlycolysis -> Citric Acid Cycle -> Oxidative PhosphorylationA fraction of this free energy will beharvested as chemical energy in theform of ATPBiological Systems Obey the PhysicalLaws of ThermodynamicsH = U + PVG = H - TSG = Gibbs Free EnergyH = EnthalpyS = EntropyU = Internal EnergyFirst Law of Thermodydamics - The Principle of Conservation of EnergyFor any physical or chemical change, the total amount ofenergy in the universe remains constant; energy may change form as it is transported from one region to another, but itcannot be created or destroyed.Living systems can couple energy requiring reactions tothose which are spontaneous (exergonic)A chemical example of reaction couplingIn all natural processes, the entropy of the universeincreases.The Second Law of ThermodynamicsThe oxidation of glucose results in a significant increasein entropy.Free Energy Calculations:G < 0, product formation is favoredG = 0, reaction at equilibriumG > 0, substrate formation favoredG = G'o + RT ln[C] [D] [A] [B]c da bAt equilibrium,If all [i] = 1 M,cdabG'o = -RT ln eq eqeqeq[C] [D] [A] [B]aA + bB cC + dD , GrxnenzymeG = G'oAdenosine triphosphate (ATP)Why is ATP a “high-energy” compound ?Garrett & GrishamFig. 3.8ATP iskineticallyverystable ATP in water is not readily convertedto ADP, but needs enzymes to mediate hydrolysis.ATP + H2O Slow reactionADP + HPO42-ATP the universal energy carrier. It releases a significant amount of free energy upon hydrolysis. But not too much so it can be a conduit between “high energy”phosphate donors and low energy acceptors.Why are the hydrolysis products (ADP+Pi) more stable than the reactants (ATP)?(1) More resonance forms per phosphate in hydrolysis productsATPADP Pi(2) Charge separation in products(3) Better solvation of productsCreatine.G = -nFEE = E' + lnoRT [e- acceptor] nF [ e- donor]E = reduction potential F = Faraday's constant n = number
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