Cellular Respiration Chapter 8 Cellular respiration Break down of carbohydrates Build up of ATP Uses oxygen Gives off carbon dioxide C6H12O6 6O2 6CO2 6H2O ATP Cellular respiration Breakdown of glucose exergonic Slow step wise breakdown Metabolic pathway Building of ATP endergonic Yeilds 36 38 mols 39 of available glucose energy Coenzymes Redox coenzymes used multiple times NAD Can accept of donate electrons Reduced NADH FAD Reduced FADH2 Glucose breakdown Four steps Glycolysis Transition reaction Krebs citric acid cycle Electron transport system Glycolysis Not in mitochondria cytoplasm Glucose 2 pyruvate molecules Occurs in every organism Glycolysis Energy investment Priming Cleavage and rearrangement Energy harvesting Oxidation ATP generation Glycolysis Priming Three reactions prime glucose Convert it so it can be cleaved Six carbon glucose six C carbon sugar diphosphate Two rxns require ATP Use 2 ATPs Glycolysis Cleavage and rearrangement 2 reactions Six carbon product of Priming split into 2 three C molecules 2 G3P three C sugar phosphate First reaction splits the molecule into G3P and another Second reaction converts other product to G3P product Isomerase Glycolysis Oxidation occurs for each G3P One rxn 2 electrons and one H transferred from G3P to NAD NADH formed G3P BGP 1 3 biphosphoglycerate Glycolysis ATP generation Four reactions create pyruvate three C Create 2 ATP s per pyruvate Substrate level phosphorylation Enzyme cleaves P from sugar and attaches to ADP 2 pyruvate 4 ATP PGAL Glycolysis overview Reactants Glucose 2 ADP 2 P 2 NAD Products net 2 pyruvate 2 ATP 2 NADH 2 H 2 H2O Glycolysis Pyruvate Oxygen available Enters mitochondria Broken down further No oxygen available Fermentation Reduction of pyruvate lactic acid Entering the mitochondria Transport protein cytosol Matrix Transition rxn Krebs cycle Cristae Electron transport system Inside the mitochondria Transition reaction Connects glycolysis to krebs cycle Pyruvate converted to 2 C acetyl group Attached to coenzyme A CoA CO2 given off NAD oxidized during reaction Krebs citric acid cycle Steps Priming Three rxns Acetyl CoA joins cycle Chemical groups rearranged Energy extraction Six rxns Four oxidations ATP formation Krebs citric acid cycle Nine reactions Reaction 1 Condensation 2 C group from acetyl CoA joins 4 C oxaloacetate Forms 6 C citrate Process is inhibited when cell s ATP concentration is high Acetyl CoA chenneled into fat synthesis instead Krebs citric acid cycle Nine reactions Reactions 2 3 isomerization Hydroxyl group of citrate repositioned Product is citrate isomer isocitrate Three carboxyl groups Krebs citric acid cycle Nine reactions Reaction 4 first oxidation First energy yielding step Isocitrate oxidized 2e removed NAD reduced Oxidized isocitrate then decarboxylated Yields CO2 and five C alpha ketoglutarate 2 carboxyl groups Krebs citric acid cycle Nine reactions Reaction 5 second oxidation Alpha ketoglutarate is decarboxylated CO2 formed Product succinyl group Succinyl group joins CoA succinyl CoA 2 e extracted in process Reduce one NAD Krebs citric acid cycle Nine reactions Reaction 6 substrate level phosphorylation Bond between succinyl and CoA broken Energy released drives synthesis of GTP guanosine triphosphate from GDP GTP converted to ATP What is the difference between the two Four C succinate remains Krebs citric acid cycle Nine reactions Reaction 7 third oxidation Succinate oxidized to fumarate FAD is electron acceptor for this not NAD FADH2 used later in electron transport chain Krebs citric acid cycle Nine reactions Reactions 8 9 regeneration of oxaloacetate Water molecule added to fumarate forming malate Malate oxidized Yields oxaloacetate 2e NAD reduced again Oxaloacetate binds to 2 C acetyl group from acetyl CoA Cycle begins again Krebs citric acid cycle Reactants 2 acetyl groups 2 ADP 2P 6 NAD 2 FAD Products 4 CO2 2 ATP 6 NADH 2 FADH2 Glycolysis review Glycolysis review Glycolysis review Glycolysis review Glycolysis review Glycolysis review Electron transport chain Reduced NADH and FADH2 Gained 2e each Travel to cristae Transfer electrons to ETC Electron transport chain NADH dehydrogenase Carrier ubiquinone Protein complex bc1 complex Carrier cytochrome c Protein complex cytochrome oxidase complex Electron transport chain NADH dehydrogenase What kind of molecule is it NADH NAD H pumped out Into intermembrane space E then passed to ubiquinone Electron transport chain Ubiquinone Accepts e from NADH dehydrgenase Accepts e from FADH2 Passed down the chain Proton pumped out be each protein complex in chain When e accepted Electron transport chain Final step cytochrome oxidase complex Uses e to reduce O2 Combines with H water O2 4H 4e 2H2O Electron transport chain Electrochemical gradient Internal compartment matrix Enzymes for krebs cycle Intermembrane space Receives protons from ETC Pumped from matrix Creates a gradient Electron transport chain Chemiosmosis What is it Electron transport chain Chemiosmosis ATP production Proton concentration in intermembrane space Diffuse back in through protein channels than matrix ATP synthase ATP formed Electron transport chain Summary Electrons from krebs cycle stimulate pumping of protons into intercellular space Concentration gradient Protons flow back in create ATP ATP transported to cytoplasm via facilitated diffusion Respiration yield Theoretical per glucose molecule Glycolysis 2 ATP 2 NADH Transition 2 NADH Krebs Per turn 1 ATP 3 NADH 1 FADH2 Total 2 ATP 6 NADH 2 FADH2 ETC receives electrons from 10 NADH 2 FADH2 Respiration yield Theoretical per glucose molecule NADH Formed inside mitochondria 3 ATP per NADH Uses all three stages of ETC Formed from glycolysis Cannot cross membrane Transport molecule carries e across to ETC Gives to FAD usually If gives to NAD 2 ATP 3 ATP Respiration yield Theoretical per glucose molecule ETC 2 FADH2 2 ATP per Only uses 2 steps of ETC Respiration yield Theoretical 2 glycolysis 2 krebs cycle 30 3 from each 10 molecules of NADH 4 2 from each 2 molecules of FADH2 2 for transport of glycolytic NADH 38 36 Actual yield Not every proton passes back into matrix through ATP synthase Membrane is leaky to protons Some protons used for other things Transport of pyruvate into mitochondria Actual yield is around 30 ATP Regulating respiration Fermentation No oxygen no aerobic respiration Products of glycolysis do not enter mitochondria NADH reduces an organic molecule Acid or alcohol Fermentation Ethanol fermentation