Extracting Energy from Food
Extracting Energy from Food Cost of ion gradients One ATP is used to 1. Pump 3 Na+ and 2 K+ against concentration gradient 2. And move 1 unit of charge against concentration gradient Low Na+ inside High Na+ outside • Provides a gradient for K+
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 • Molecules diffuse from high to low concentration • High conc. differences have chemical potential energy
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)
ADP and Pi have ~7.5Kcal/mol less energy than ATP when all are a concentration of 1M REAL cells have more ATP than ADP o Moving ATP/ADP towards equilibrium provides energy to move other reaction away from equilibrium
ATP hydrolysis -> ~12Kcal /mol of ATP (chemical potential energy) Glycolysis - No O2 used, no CO2 produced - 1 glucose (6C) in, 2 pyruvate out (3C each) o gains 2mol ATP per Glucose - makes NADH (form of energy) - pyruvate -> lactate and lose NADH Mitochondria • glycolysis happens in mitochondria • pyruvate enters mitochondria (combines with O2) o most ATP production in mitochondria Citric Acid Cycle Pyruvate -> acetylcoenzyme A (acetyl CoA) (mitochondria) • No O2 used – 2CO2 / per glucose • O2 from glucose – more NADH made: remainder sent to lactate • Fat metabolism makes acetylCoA – fat and carbohydrate share common pathway NEXT STEP • 4 CO2 / glucose • O2 from food or water
• 2C in 2C leave as CO2 • 2GTP/glucose • 6ADH/glucose • 2FADH Energy Currency of the Cell 1GTP=1ATP 1 FADH2 = 2 ATP 1 NADH = 3 ATP Electron Transport Train • Food is oxidised with NAD and FAD not O2 • Reduced NADH and FADH2 feed into electron transport chain o Oxidised NADH and FADH NADH Powers 3 H+ pumps FADH2 enters
ubiquinone – powers 2 pumps
ATP synthesis H+ produces electrochemical gradient -140mV potential (inside negative) • 1.4 units pH difference • Large electrochemical gradient pushes H+ATPase backwards o Moves towards equilibrium down its electrochemical gradient Oxidative Phosphorylation
ATP synthesis Glycolysis gives 2mol ATP per mol glucose - Oxidative phosphorylation gives 36 mol of ATP per mol Glucose - Energy from C-C and C-H bonds - Produces usable energy in a 21% O2 atmosphere
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 • Molecules diffuse from high to low concentration • High conc. differences have chemical potential energy
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)
ADP and Pi have ~7.5Kcal/mol less energy than ATP when all are a concentration of 1M REAL cells have more ATP than ADP o Moving ATP/ADP towards equilibrium provides energy to move other reaction away from equilibrium
ATP hydrolysis -> ~12Kcal /mol of ATP (chemical potential energy) Glycolysis - No O2 used, no CO2 produced - 1 glucose (6C) in, 2 pyruvate out (3C each) o gains 2mol ATP per Glucose - makes NADH (form of energy) - pyruvate -> lactate and lose NADH Mitochondria • glycolysis happens in mitochondria • pyruvate enters mitochondria (combines with O2) o most ATP production in mitochondria Citric Acid Cycle Pyruvate -> acetylcoenzyme A (acetyl CoA) (mitochondria) • No O2 used – 2CO2 / per glucose • O2 from glucose – more NADH made: remainder sent to lactate • Fat metabolism makes acetylCoA – fat and carbohydrate share common pathway NEXT STEP • 4 CO2 / glucose • O2 from food or water
• 2C in 2C leave as CO2 • 2GTP/glucose • 6ADH/glucose • 2FADH Energy Currency of the Cell 1GTP=1ATP 1 FADH2 = 2 ATP 1 NADH = 3 ATP Electron Transport Train • Food is oxidised with NAD and FAD not O2 • Reduced NADH and FADH2 feed into electron transport chain o Oxidised NADH and FADH NADH Powers 3 H+ pumps FADH2 enters
ubiquinone – powers 2 pumps
ATP synthesis H+ produces electrochemical gradient -140mV potential (inside negative) • 1.4 units pH difference • Large electrochemical gradient pushes H+ATPase backwards o Moves towards equilibrium down its electrochemical gradient Oxidative Phosphorylation
ATP synthesis Glycolysis gives 2mol ATP per mol glucose - Oxidative phosphorylation gives 36 mol of ATP per mol Glucose - Energy from C-C and C-H bonds - Produces usable energy in a 21% O2 atmosphere
