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Transcript
Extracting Energy from Food Cost of ion gradients One ATP is used to 1. Pump3Na+and2K+againstconcentration gradient 2. Andmove1unitofchargeagainst concentrationgradient Low Na+ inside High Na+ outside • ProvidesagradientforK+ Energy in a chemical reaction can be calculated from: is the energy change when all reactants are present @1M & STP for ATP ~ -7.5Kcal/mol • • Electrical and chemical potential energy • Moleculesdiffusefromhightolow concentration • Highconc.differenceshavechemical potentialenergy Voltage generates electrical potential energy Cost of Na+/K+ ATPase Total cost =42KJ/mol ATP About 10 Kcal/mol of ATP used Thermodynamic Limits Pumps move against the concentration gradient – if not enough energy they move backwards (energy from ATP must be greater than sum of chemical and electrical potential energy) ADPandPihave~7.5Kcal/mollessenergy thanATPwhenallareaconcentrationof 1M REALcellshavemoreATPthanADP o MovingATP/ADPtowards equilibriumprovidesenergytomove otherreactionawayfrom equilibrium ATP hydrolysis -> ~12Kcal /mol of ATP (chemical potential energy) Glycolysis - NoO2used,noCO2produced - 1glucose(6C)in,2pyruvateout(3Ceach) o gains2molATPperGlucose - makesNADH(formofenergy) - pyruvate->lactateandloseNADH Mitochondria • glycolysishappensinmitochondria • pyruvateentersmitochondria(combines withO2) o mostATPproductionin mitochondria Citric Acid Cycle Pyruvate -> acetylcoenzyme A (acetyl CoA) (mitochondria) • NoO2used–2CO2/perglucose • O2fromglucose–moreNADHmade: remaindersenttolactate • FatmetabolismmakesacetylCoA–fatand carbohydratesharecommonpathway NEXT STEP • 4CO2/glucose • O2fromfoodorwater • 2Cin2CleaveasCO2 • 2GTP/glucose • 6ADH/glucose • 2FADH Energy Currency of the Cell 1GTP=1ATP 1 FADH2 = 2 ATP 1 NADH = 3 ATP Electron Transport Train • FoodisoxidisedwithNADandFADnotO2 • ReducedNADHandFADH2feedinto electrontransportchain o OxidisedNADHandFADH NADH Powers 3 H+ pumps FADH2 enters ubiquinone – powers 2 pumps ATP synthesis H+ produces electrochemical gradient -140mV potential (inside negative) • 1.4unitspHdifference • Largeelectrochemicalgradientpushes H+ATPasebackwards o Movestowardsequilibriumdownits electrochemicalgradient Oxidative Phosphorylation ATP synthesis Glycolysis gives 2mol ATP per mol glucose - Oxidativephosphorylationgives36molof ATPpermolGlucose - EnergyfromC-CandC-Hbonds - Producesusableenergyina21%O2 atmosphere