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Light energy. ECOSYSTEM. Photosynthesis in chloroplasts. Organic molecules. CO 2 + H 2 O. + O 2. Cellular respiration in mitochondria. ATP. ATP powers most cellular work. Heat energy. becomes oxidized (loses electron). becomes reduced (gains electron). becomes oxidized.
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Light energy ECOSYSTEM Photosynthesis in chloroplasts Organic molecules CO2 + H2O + O2 Cellular respiration in mitochondria ATP ATP powers most cellular work Heat energy
becomes oxidized (loses electron) becomes reduced (gains electron)
becomes oxidized becomes reduced
Reactants Products becomes oxidized becomes reduced Carbon dioxide Water Methane (reducing agent) Oxygen (oxidizing agent)
becomes oxidized becomes reduced
2 e– + 2 H+ 2 e– + H+ H+ NADH Dehydrogenase Reduction of NAD+ NAD+ 2[H] H+ + + Oxidation of NADH Nicotinamide (reduced form) Nicotinamide (oxidized form)
1/2 O2 H2 + 1/2 O2 + 2 H (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– 1/2 O2 2 H+ H2O H2O (a) Uncontrolled reaction (b) Cellular respiration
Electrons carried via NADH and FADH2 Electrons carried via NADH Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Glycolysis Pyruvate Glucose Mitochondrion Cytosol ATP ATP ATP Substrate-level phosphorylation Substrate-level phosphorylation Oxidative phosphorylation
Enzyme Enzyme ADP P Substrate ATP + Product
Energy investment phase Glucose 2 ADP + 2 2 ATP used P Energy payoff phase formed 4 ADP + 4 P 4 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+ 2 Pyruvate + 2 H2O Net 2 Pyruvate + 2 H2O Glucose 4 ATP formed – 2 ATP used 2 ATP 2 NAD+ + 4 e– + 4 H+ 2 NADH + 2 H+
Glucose ATP 1 Hexokinase ADP Glucose-6-phosphate 2 Phosphoglucoisomerase Fructose- 1, 6-bisphosphate 4 Fructose-6-phosphate Aldolase ATP 3 Phosphofructokinase ADP 5 Isomerase Fructose- 1, 6-bisphosphate 4 Aldolase 5 Isomerase Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate Glyceraldehyde- 3-phosphate Dihydroxyacetone phosphate
2 NAD+ 6 Triose phosphate dehydrogenase P 2 2 NADH i + 2 H+ 2 1, 3-Bisphosphoglycerate 2 ADP 7 Phosphoglycerokinase 2 ATP Phosphoenolpyruvate 2 2 ADP 2 3-Phosphoglycerate 8 10 Phosphoglyceromutase Pyruvate kinase 2 ATP 2 2-Phosphoglycerate 9 Enolase 2 H2O 2 Phosphoenolpyruvate 2 ADP 10 Pyruvate kinase 2 ATP Pyruvate 2 2 Pyruvate
CYTOSOL MITOCHONDRION NAD+ NADH + H+ 2 1 3 Acetyl CoA Coenzyme A Pyruvate CO2 Transport protein
Pyruvate CO2 NAD+ CoA NADH + H+ Acetyl CoA CoA CoA Citric acid cycle 2 CO2 FADH2 3 NAD+ NADH 3 FAD + 3 H+ ADP + P i ATP
Acetyl CoA CoA—SH NADH H2O 1 +H+ NAD+ Oxaloacetate 8 2 Malate Citrate Isocitrate NAD+ Citric acid cycle NADH 3 + H+ 7 H2O CO2 Fumarate CoA—SH -Keto- glutarate 4 6 CoA—SH 5 FADH2 CO2 NAD+ FAD Succinate NADH P i + H+ Succinyl CoA GDP GTP ADP ATP
NADH 50 e– 2 NAD+ FADH2 e– 2 FAD Multiprotein complexes FAD 40 FMN Fe•S Fe•S Q Cyt b Fe•S 30 Cyt c1 IV Free energy (G) relative to O2 (kcal/mol) Cyt c Cyt a Cyt a3 20 e– 2 10 (from NADH or FADH2) O2 2 H+ + 1/2 0 H2O
INTERMEMBRANE SPACE H+ Stator Rotor Internal rod Cata- lytic knob ADP + ATP P i MITOCHONDRIAL MATRIX
H+ H+ H+ H+ Protein complex of electron carriers Cyt c V Q ATP synthase H2O 2 H+ + 1/2O2 FADH2 FAD NAD+ NADH ADP + ATP P i (carrying electrons from food) H+ Chemiosmosis Electron transport chain 1 2 Oxidative phosphorylation
Electron shuttles span membrane MITOCHONDRION CYTOSOL 2 NADH or 2 FADH2 2 NADH 6 NADH 2 FADH2 2 NADH Oxidative phosphorylation: electron transport and chemiosmosis Glycolysis Citric acid cycle 2 Acetyl CoA 2 Pyruvate Glucose + 2 ATP + 2 ATP + about 32 or 34 ATP About 36 or 38 ATP Maximum per glucose:
2 ADP + 2 Pi 2 ATP Glucose Glycolysis 2 Pyruvate 2 NAD+ 2 NADH CO2 2 + 2 H+ 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation 2 ADP + 2 Pi 2 ATP Glucose Glycolysis 2 NADH 2 NAD+ + 2 H+ 2 Pyruvate 2 Lactate (b) Lactic acid fermentation
Glucose Glycolysis CYTOSOL Pyruvate O2 present: Aerobic cellular respiration No O2 present: Fermentation MITOCHONDRION Acetyl CoA Ethanol or lactate Citric acid cycle
Proteins Fats Carbohydrates Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde-3- P NH3 Pyruvate Acetyl CoA Citric acid cycle Oxidative phosphorylation
Glucose AMP Glycolysis Fructose-6-phosphate Stimulates + Phosphofructokinase – – Fructose-1,6-bisphosphate Inhibits Inhibits Pyruvate ATP Citrate Acetyl CoA Citric acid cycle Oxidative phosphorylation