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?

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

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

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

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

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

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

Enzyme Enzyme ADP P Substrate ATP Product Figure 9.7 Figure 9.7 Substrate-level phosphorylation. Product

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+

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

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

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

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

Multiprotein complexes I 40 II Figure 9.13 NADH 50 2 e NAD FADH2 2 e FAD Multiprotein complexes I 40 FMN II FeS FeS Q III Cyt b 30 FeS 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

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

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

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

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

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

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

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