Chapter 7: Cellular Respiration pages 135-154 7.1 Catabolic Pathways yield energy by oxidizing organic fuels 7.2 Glycolysis harvests chemical energy by oxidizing glucose to pyruvate 7.3 After pyruvate is oxidized, the citric acid cycle completes the energy yielding oxidation of organic molecules 7.4 During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis 7.5 Fermentation and anaerobic respiration enable cells to produce ATP 7.6 Glycolysis and the citric acid cycle connect to many other metabolic pathways C6H12O6  6 O2  6 CO2  6 H2O  Energy (ATP  heat) http://www.mhhe.com/biosci/bio_animations/MH01_CellularRespiration_Web/index.html

Light energy ECOSYSTEM Photosynthesis in chloroplasts Organic Figure 7.2 Light energy ECOSYSTEM Photosynthesis in chloroplasts Organic molecules CO2  H2O  O2 Cellular respiration in mitochondria Figure 7.2 Energy flow and chemical recycling in ecosystems ATP powers most cellular work ATP Heat energy 2

Concept 7.1: Catabolic pathways yield energy by oxidizing organic fuels The breakdown of organic molecules is _________ Fermentation: Aerobic respiration: Anaerobic respiration: Cellular respiration includes both aerobic and anaerobic respiration but is often used to refer to aerobic respiration © 2014 Pearson Education, Inc. 3

Figure 7.3 EXAMPLE OF A REDOX REACTION Reactants Products becomes oxidized becomes reduced Figure 7.3 Methane combustion as an energy-yielding redox reaction Methane (reducing agent) Oxygen (oxidizing agent) Carbon dioxide Water 4

Bozeman Biology: Redox Reactions Figure 7.UN03 becomes oxidized becomes reduced Figure 7.UN03 In-text figure, cellular respiration redox reaction, p. 137 Bozeman Biology: Redox Reactions http://www.youtube.com/watch?v=RX6rh-eeflM 5

The Importance of NAD+/NADH 2 e− 2 H 2 e−  H NAD NADH H Dehydrogenase Reduction of NAD  2[H] (from food)  H Oxidation of NADH Nicotinamide (reduced form) Nicotinamide (oxidized form) Figure 7.4 NAD+ as an electron shuttle https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/819779/How_the_NADplus_Works.swf::How%20the%20NAD+%20Works 6

A Preview of Cellular Respiration Electrons via NADH and FADH2 Electrons via NADH Oxidative phosphorylation: electron transport and chemiosmosis Pyruvate oxidation Glycolysis Citric acid cycle Glucose Pyruvate Acetyl CoA CYTOSOL MITOCHONDRION Figure 7.6-3 An overview of cellular respiration (step 3) ATP ATP ATP Substrate-level Substrate-level Oxidative 7

Figure 7.7: Substrate Level Phosphorylation Enzyme Enzyme ADP P Substrate  ATP Figure 7.7 Substrate-level phosphorylation Product 8

Concept 7.2: Glycolysis harvests chemical energy by oxidizing glucose to pyruvate Glycolysis means: Glycolysis occurs in: Glycolysis occurs whether or not: http://highered.mcgraw-hill.com/sites/0072507470/student_view0/chapter25/animation__how_glycolysis_works.html © 2014 Pearson Education, Inc. 9

Energy Investment Phase Figure 7.8 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 7.8 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 10

Glycolysis: Energy Investment Phase Figure 7.9a Glycolysis: Energy Investment Phase Glyceraldehyde 3-phosphate (G3P) ATP Glucose 6-phosphate Fructose 6-phosphate ATP Fructose 1,6-bisphosphate Glucose ADP ADP Isomerase 5 Hexokinase Phosphogluco- isomerase Phospho- fructokinase Aldolase Dihydroxyacetone phosphate (DHAP) 1 4 2 3 Figure 7.9a A closer look at glycolysis (part 1: investment phase) 11

Glycolysis: Energy Payoff Phase Figure 7.9b Glycolysis: Energy Payoff Phase 2 ATP 2 ATP 2 NADH 2 H2O Glyceraldehyde 3-phosphate (G3P) 2 ADP 2 NAD  2 H 2 ADP 2 2 2 2 2 Triose phosphate dehydrogenase Phospho- glycerokinase Phospho- glyceromutase Enolase Pyruvate kinase 2 P i 9 1,3-Bisphospho- glycerate 7 3-Phospho- glycerate 8 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) 10 Pyruvate 6 Figure 7.9b A closer look at glycolysis (part 2: payoff phase) 12

Inputs Glycolysis Glucose ATP  2 NADH Figure 7.UN11 Inputs Outputs Glycolysis Glucose 2 Pyruvate  2 ATP  2 NADH Figure 7.UN11 Summary of key concepts: pyruvate 13

Concept 7.3: After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules In the presence of O2, pyruvate enters the mitochondrion (in eukaryotic cells), where the oxidation of glucose is completed Before the citric acid cycle can begin, pyruvate must be converted to acetyl coenzyme A (acetyl CoA), which links glycolysis to the citric acid cycle © 2014 Pearson Education, Inc. 14

Citric acid cycle Oxidative phosphorylation Pyruvate oxidation Concept 7.3: After pyruvate is oxidized, the citric acid cycle completes the energy-yielding oxidation of organic molecules Citric acid cycle Oxidative phosphorylation Pyruvate oxidation Glycolysis Figure 7.UN07 In-text figure, mini-map, pyruvate oxidation, p. 142 ATP ATP ATP 15

Figure 7.10 Pyruvate (from glycolysis, 2 molecules per glucose) https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/819779/How_the_Krebs_Cycle_Works.swf::How%20the%20Krebs%20Cycle%20Works CYTOSOL CO2 NAD CoA NADH  H Acetyl CoA MITOCHONDRION CoA CoA Citric acid cycle Figure 7.10 An overview of pyruvate oxidation and the citric acid cycle 2 CO2 FADH2 3 NAD FAD 3 NADH  3 H ADP  P i ATP 16

Citric acid cycle Figure 7.11-6 Acetyl CoA 1 Oxaloacetate 8 2 Malate CoA-SH NADH 1  H H2O NAD Oxaloacetate 8 2 Malate Citrate Isocitrate NAD Citric acid cycle 3 NADH 7  H H2O CO2 Fumarate CoA-SH -Ketoglutarate Figure 7.11-6 A closer look at the citric acid cycle (step 8) 6 4 CoA-SH 5 FADH2 CO2 NAD FAD Succinate P NADH i GTP GDP Succinyl CoA  H ADP ATP formation ATP 17

CO2 Inputs Outputs 2 Pyruvate 2 Acetyl CoA 2 ATP 8 NADH Citric acid Figure 7.UN12 Inputs Outputs 2 Pyruvate 2 Acetyl CoA 2 ATP 8 NADH Citric acid cycle 2 Oxaloacetate CO2 6 2 FADH2 Figure 7.UN12 Summary of key concepts: citric acid cycle 18

Oxidative phosphorylation: electron transport and chemiosmosis Citric Concept 7.4: During oxidative phosphorylation, chemiosmosis couples electron transport to ATP synthesis Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle Pyruvate oxidation Glycolysis Figure 7.UN09 In-text figure, mini-map, oxidative phosphorylation, p. 144 ATP ATP ATP https://highered.mcgraw-hill.com/olcweb/cgi/pluginpop.cgi?it=swf::640::480::/sites/dl/free/0073532223/819779/Electron_Transport_System_and_ATP_Synthesis.swf::Electron%20Transport%20System%20and%20ATP%20Synthesis 19

H INTERMEMBRANE SPACE Stator Rotor Internal rod Catalytic knob ADP  Figure 7.13 H INTERMEMBRANE SPACE Stator Rotor Internal rod Catalytic knob Figure 7.13 ATP synthase, a molecular mill ADP  P ATP MITOCHONDRIAL MATRIX i 20

Electron transport chain Oxidative phosphorylation Figure 7.14 H H Protein complex of electron carriers H H Cyt c IV Q III I ATP synthase II 2 H  ½ O2 H2O FADH2 FAD NADH NAD Figure 7.14 Chemiosmosis couples the electron transport chain to ATP synthesis ADP  P ATP i (carrying electrons from food) H 1 Electron transport chain 2 Chemiosmosis Oxidative phosphorylation 21

An Accounting of ATP Production by Cellular Respiration During cellular respiration, most energy flows in the following sequence: glucose  NADH  electron transport chain  proton-motive force  ATP About 34% of the energy in a glucose molecule is transferred to ATP during cellular respiration, making about 32 ATP There are several reasons why the number of ATP molecules is not known exactly Bozeman Biology: ATP http://www.youtube.com/watch?v=5GMLIMIVUvo © 2014 Pearson Education, Inc. 22

Electron shuttles span membrane MITOCHONDRION 2 NADH CYTOSOL or Figure 7.15 Electron shuttles span membrane MITOCHONDRION 2 NADH CYTOSOL or 2 FADH2 2 NADH 2 NADH 6 NADH 2 FADH2 Glycolysis Pyruvate oxidation 2 Acetyl CoA Oxidative phosphorylation: electron transport and chemiosmosis Citric acid cycle 2 Pyruvate Glucose  2 ATP Figure 7.15 ATP yield per molecule of glucose at each stage of cellular respiration  2 ATP  about 26 or 28 ATP About 30 or 32 ATP Maximum per glucose: 23

Concept 7.5: Fermentation and anaerobic respiration enable cells to produce ATP without the use of oxygen Most cellular respiration requires O2 to produce ATP Without O2… In that case, glycolysis couples with fermentation or anaerobic respiration to produce ATP Anaerobic respiration uses an electron transport chain with a final electron acceptor other than O2, for example, sulfate http://www.youtube.com/watch?v=cDC29iBxb3w Fermentation uses substrate-level phosphorylation instead of an electron transport chain to generate ATP © 2014 Pearson Education, Inc. 24

Types of Fermentation Fermentation consists of glycolysis plus reactions that regenerate NAD, which can be reused by glycolysis Two common types are alcohol fermentation and lactic acid fermentation © 2014 Pearson Education, Inc. 25

(a) Alcohol fermentation Figure 7.16a 2 ADP  2 P 2 ATP i Glucose Glycolysis 2 Pyruvate 2 NAD 2 NADH 2 CO2  2 H Figure 7.16a Fermentation (part 1: alcohol) 2 Acetaldehyde 2 Ethanol (a) Alcohol fermentation 26

(b) Lactic acid fermentation Figure 7.16b 2 ADP  2 P 2 ATP i Glucose Glycolysis 2 NAD 2 NADH  2 H 2 Pyruvate Figure 7.16b Fermentation (part 2: lactic acid) 2 Lactate (b) Lactic acid fermentation 27

Comparing Fermentation with Anaerobic and Aerobic Respiration All use ___________________ to oxidize glucose and harvest chemical energy of food In all three, ______ is the oxidizing agent that accepts electrons during glycolysis The processes have _________ final electron acceptors: an organic molecule (such as pyruvate or acetaldehyde) in fermentation and _____ in cellular respiration Cellular respiration produces _____ATP per glucose molecule; fermentation produces ____ ATP per glucose molecule © 2014 Pearson Education, Inc. 28

Ethanol, lactate, or other products Citric acid cycle Figure 7.17 Glucose Glycolysis CYTOSOL Pyruvate No O2 present: Fermentation O2 present: Aerobic cellular respiration MITOCHONDRION Ethanol, lactate, or other products Acetyl CoA Figure 7.17 Pyruvate as a key juncture in catabolism Citric acid cycle 29

Concept 7.6: Glycolysis and the citric acid cycle connect to many other metabolic pathways Gycolysis and the citric acid cycle are major intersections to various catabolic and anabolic pathways © 2014 Pearson Education, Inc. 30

Amino acids Fatty acids Citric acid cycle Oxidative phosphorylation Figure 7.18-5 Proteins Carbohydrates Fats Amino acids Sugars Glycerol Fatty acids Glycolysis Glucose Glyceraldehyde 3- P NH3 Pyruvate Figure 7.18-5 The catabolism of various molecules from food (step 5) Acetyl CoA Citric acid cycle Oxidative phosphorylation 31

Biosynthesis (Anabolic Pathways) The body uses small molecules to build other substances Some of these small molecules come directly from food; others can be produced during glycolysis or the citric acid cycle Bozeman Biology Overview of Cellular Respiration: http://www.youtube.com/watch?v=Gh2P5CmCC0M © 2014 Pearson Education, Inc. 32