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Cellular Respiration Remember: In order for cells to survive, it must have energy to do work!!! ATP is the energy that’s available to do work! How does living cells utilize the chemical form of energy from organic molecules to generate ATP?
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Photosynthesis in chloroplasts Cellular respiration in mitochondria
Figure 9.2 Light energy ECOSYSTEM Photosynthesis in chloroplasts O2 Organic molecules CO2 H2O Cellular respiration in mitochondria Figure 9.2 Energy flow and chemical recycling in ecosystems. **This is one of the questions that people missed in the photosynthesis idea!! Why is photosynthesis important transfer of energy, why is cellular respiration important? Utilize chemical energy and transfer it to ATP which can be used to do work!!! ATP powers most cellular work ATP Heat energy
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Catabolic Pathway: yield energy by oxidizing organic fuels
Figure 9.UN03 Catabolic Pathway: yield energy by oxidizing organic fuels Exergonic !!! Fermentation: without O2 Aerobic respiration: use O2, yields ATP Anaerobic respiration: doesn’t use O2 Figure 9.UN03 In-text figure, p. 165 Reminder: glucose turns into Carbon dioxide, oxygen is a hydrogen acceptor (electron acceptor) to be reduced
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Redox Reaction LEO goes GER Glucose = oxidized, oxygen = reduced
Figure 9.UN03 Redox Reaction becomes oxidized becomes reduced Figure 9.UN03 In-text figure, p. 165 Reminder: glucose turns into Carbon dioxide, oxygen is a hydrogen acceptor (electron acceptor) to be reduced LEO goes GER Glucose = oxidized, oxygen = reduced
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Key Player: NAD+ Figure 9.4 NAD NADH Dehydrogenase Reduction of NAD
(from food) Oxidation of NADH Nicotinamide (oxidized form) Nicotinamide (reduced form) Figure 9.4 NAD as an electron shuttle. NADH passes electrons down the ETC, seriers of reactions
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Controlled release of energy for synthesis of ATP
Figure 9.5 H2 1/2 O2 2 H 1/2 O2 (from food via NADH) Controlled release of energy for synthesis of ATP 2 H+ 2 e ATP Explosive release of heat and light energy ATP Electron transport chain Free energy, G Free energy, G ATP 2 e Figure 9.5 An introduction to electron transport chains. ETC passes electrons in series of steps instead of one explosive releasing reaction. Oxygen pulls electrons down the chain (a great oxydizing agent ...so it allows for final electron acceptor 1/2 O2 2 H+ H2O H2O (a) Uncontrolled reaction (b) Cellular respiration
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Electrons carried via NADH Electrons carried via NADH and FADH2
Figure 9.6-3 Electrons carried via NADH Electrons carried via NADH and FADH2 Oxidative phosphorylation: electron transport and chemiosmosis Pyruvate oxidation Glycolysis Citric acid cycle Glucose Pyruvate Acetyl CoA CYTOSOL MITOCHONDRION Figure 9.6 An overview of cellular respiration. The most ATP (90%) is at the last step (oxidative phosphorylation) a redox reaction Glycolysis and Citric Acid Cycle forms small amount of ATP through substrate-level phosphorylation ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation
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Enzyme Enzyme ADP P Substrate ATP Product Figure 9.7
Figure 9.7 Substrate-level phosphorylation. Product
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Energy Investment Phase
Figure 9.8 Energy Investment Phase Glucose 2 ADP 2 P 2 ATP used Energy Payoff Phase 4 ADP 4 P 4 ATP formed 2 NAD+ 4 e 4 H+ 2 NADH 2 H+ Figure 9.8 The energy input and output of glycolysis. 2 Pyruvate 2 H2O Net Glucose 2 Pyruvate 2 H2O 4 ATP formed 2 ATP used 2 ATP 2 NAD+ 4 e 4 H+ 2 NADH 2 H+
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MITOCHONDRION CYTOSOL CO2 Coenzyme A NAD NADH + H Acetyl CoA
Figure 9.10 MITOCHONDRION CYTOSOL CO2 Coenzyme A 1 3 2 NAD NADH + H Acetyl CoA Figure 9.10 Oxidation of pyruvate to acetyl CoA, the step before the citric acid cycle. Acetyl coA links glycolysis to citric acid cycle (only happens when oxygen is present) Pyruvate Transport protein
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Citric Acid Cycle (Krebs Cycle) Pyruvate CO2 NAD CoA NADH + H
Figure 9.11 Pyruvate CO2 NAD CoA NADH + H Acetyl CoA Citric Acid Cycle (Krebs Cycle) CoA CoA Citric acid cycle 2 CO2 Figure 9.11 An overview of pyruvate oxidation and the citric acid cycle.\ COMPLETE Breakdown of the glucose to carbon dioxide What’s made each turn? (two turns total) FADH2 3 NAD FAD 3 NADH + 3 H ADP + P i ATP
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Citric acid cycle Figure 9.12-8 Acetyl CoA Oxaloacetate Malate Citrate
CoA-SH NADH + H 1 H2O NAD Oxaloacetate 8 2 Malate Citrate Isocitrate NAD Citric acid cycle NADH 3 7 + H H2O CO2 Fumarate CoA-SH -Ketoglutarate Figure 9.12 A closer look at the citric acid cycle. 4 6 CoA-SH 5 FADH2 CO2 NAD FAD Succinate P i NADH GTP GDP Succinyl CoA + H ADP ATP
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Acetyl CoA 1 Oxaloacetate 2 Citrate Isocitrate H2O CoA-SH Figure 9.12a
Figure 9.12 A closer look at the citric acid cycle. Oxaloacetate 2 Citrate Isocitrate
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Multiprotein complexes I 40 II
Figure 9.13 NADH 50 2 e NAD FADH2 2 e FAD Multiprotein complexes I 40 FMN II FeS FeS Q III Cyt b 30 FeS Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c Cyt a Cyt a3 20 Figure 9.13 Free-energy change during electron transport. NADH and FADH2 carries the energy to ETC, powers ATP Synthase Role of Oxygen electron acceptor 10 2 e (originally from NADH or FADH2) 2 H + 1/2 O2 H2O
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Chemiosmosis INTERMEMBRANE SPACE H Stator Rotor Internal rod
Figure 9.14 INTERMEMBRANE SPACE Chemiosmosis H Stator Rotor Internal rod Figure 9.14 ATP synthase, a molecular mill. Chemiosmosis Energy Coupling: exergonic reaction of H+ rushing through the membrane endogonic process of phosphorylating ADP Catalytic knob ADP + P i ATP MITOCHONDRIAL MATRIX
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Protein complex of electron carriers
Figure 9.15 H H H Protein complex of electron carriers H Cyt c IV Q III I ATP synth- ase II 2 H + 1/2O2 H2O FADH2 FAD Figure 9.15 Chemiosmosis couples the electron transport chain to ATP synthesis. NAD NADH ADP P i ATP (carrying electrons from food) H 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation
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Oxidative phosphorylation: electron transport and chemiosmosis
Figure 9.16 Electron shuttles span membrane MITOCHONDRION 2 NADH or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis Pyruvate oxidation Citric acid cycle Glucose 2 Pyruvate 2 Acetyl CoA Figure 9.16 ATP yield per molecule of glucose at each stage of cellular respiration. 2 ATP 2 ATP about 26 or 28 ATP About 30 or 32 ATP Maximum per glucose: CYTOSOL
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i i Figure 9.17 2 ATP 2 ATP Glucose Glycolysis Glucose
2 ADP 2 P i 2 ATP 2 ADP 2 P i 2 ATP Glucose Glycolysis Glucose Glycolysis 2 Pyruvate 2 NAD 2 NADH 2 CO2 2 NAD 2 NADH 2 H 2 H 2 Pyruvate Figure 9.17 Fermentation. 2 Ethanol 2 Acetaldehyde 2 Lactate (a) Alcohol fermentation (b) Lactic acid fermentation
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Ethanol, lactate, or other products
Figure 9.18 Glucose Glycolysis CYTOSOL Pyruvate No O2 present: Fermentation O2 present: Aerobic cellular respiration MITOCHONDRION Ethanol, lactate, or other products Acetyl CoA Figure 9.18 Pyruvate as a key juncture in catabolism. Citric acid cycle
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Oxidative phosphorylation
Figure 9.19 Proteins Carbohydrates Fats Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde 3- P NH3 Pyruvate Acetyl CoA Figure 9.19 The catabolism of various molecules from food. Citric acid cycle Oxidative phosphorylation
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Oxidative phosphorylation
Figure 9.20 Glucose AMP Glycolysis Fructose 6-phosphate Stimulates Phosphofructokinase Fructose 1,6-bisphosphate Inhibits Inhibits Pyruvate ATP Citrate Acetyl CoA Figure 9.20 The control of cellular respiration. Citric acid cycle Oxidative phosphorylation
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