Cellular Respiration LEOxidized and GEReduced H + + e - -Therefore H atoms are removed electrons are also removed. Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. energy glucose Reduction Oxidation 6H 2 O6CO 2 6O 2 C 6 H 12 O

NAD + and FAD Coenzyme of oxidation-reduction Electron Carriers

Cellular Respiration Glycolysis Prep Phase (acetyl CoA) Citric Acid Cycle (Kreb’s Cycle) Electron Transport Chain (ETC)

An overview of cellular respiration (Layer 1)

Glycolysis  Glucose is broken down into two molecules of pyruvate Occurs in the cytoplasm ATP is formed Does not use oxygen

Glycolysis Takes place in the cytoplasm NAD +

What’s Happened so far? Glycolysis O 2 Used ? Glucose C now Product: ATP # NADH # GlycolysisNo2 Pyruvates22 pyruvate glucose

Pyruvate as a key juncture in catabolism

If O 2 is NOT available Fermentation, an anaerobic process, occurs in the cytoplasm.  During fermentation, glucose is incompletely metabolized to lactate, or to CO 2 and alcohol (depending on the organism).

Fermentation Helps Produce Numerous Food Products Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.

Alcoholic Fermentation Pyruvate + NADH Ethanol + CO 2 + NAD + Vinegar

Lactic Acid Fermentation Pyruvate + NADH Lactic Acid + NAD +

If O 2 is available Preparatory (prep) reaction, a aerobic process, occurs in the mitochondria. Occurs in mitochondria Two carbons are released as CO 2 (one from each pyruvate) 14

What’s Happened so far? Krebs Cycle Original C of glucose are now ATPNADHFADH 2 Glycolysis2 pyruvate22 Acetyl CoA formation 2 CO 2 & 2 acetyl CoA 2 Krebs Cycle Total glucose

An overview of cellular respiration (Layer 2)

Citric acid cycle Occurs in the matrix of the mitochondrion and produces NADH and FADH 2 Releases 4 carbons as CO 2 Produces 2 ATP molecules 17

What’s Happened so far? Krebs Cycle Original C of glucose are now ATPNADHFADH 2 Glycolysis2 pyruvate22 Acetyl CoA formation 2 CO 2 & 2 acetyl CoA 2 Krebs Cycle4 more CO Total6 CO glucose

An overview of cellular respiration (Layer 3)

Mitochondrion Structure and Function 20 © Dr. Donald Fawcett and Dr. Porter/Visuals Unlimited Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. Cristae: location of the electron transportchain (ETC) Matrix: location of the prep reaction and the citric acid cycle outer membrane inner membrane intermembrane space cristae matrix 45,0003X

Organization and Function of the Electron Transport Chain Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. 2 O2O P H+H+ e : e : Electron transport chain high energy electron ATP channel protein Intermembrane space ATP synthase complex low energy electron cytochrome oxidase cytochrome c NADH-Q reductase cytochrome reductase coenzyme Q NADH Matrix FADH 2 FAD + NAD + 2 e-e- 2 ADPATP 32 ADP or 34 4 ADP netATP 4 ATP total 2ADP 2ATP Glycolysis glucosepyruvate Preparatory reaction Citric acid cycle Electron transport chain and chemiosmosis NADH and FADH 2 NADH e-e- e-e- e-e- e-e- e-e- e-e- 32 or 34 H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP ADP H2OH2O H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ H+H+ ATP Chemiosmosis

Electron Transport Chain (ETC) Extracts energy from NADH & FADH 2 Passes electrons from higher to lower energy states Produces 32 or 34 molecules of ATP

Max of 36 ATP per Glucose

Substrate-level ATP Synthesis Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. P P P enzyme ADP ATP BPG 3PG

Inside the Mitochondria Electron Transport Chain (ETC) Location:  Eukaryotes: cristae of the mitochondria  Aerobic prokaryotes: plasma membrane The electron transport chain  Receives electrons from NADH & FADH 2  Produces ATP by oxidative phosphorylation Oxygen serves as the final electron acceptor  Oxygen combines with hydrogen ions to form water

*H+ is pumped against its gradient into the mitochondrial matrix *Energy for active transport comes from electrons

Inside the Mitochondria Energy yield from glucose metabolism:  Net yield per glucose: From glycolysis – 2 ATP From citric acid cycle – 2 ATP From electron transport chain – 32 or 34 ATP  Energy content: Reactant (glucose) 686 kcal Energy yield (36 ATP) 263 kcal Efficiency is 39% The rest of the energy from glucose is lost as heat

Energy rich molecules: carbohydrates, fats, and proteins Catabolism : Break down molecules usually exergonic (release energy) Anabolism build molecules: usually endergonic (consume energy) 29 ATP Electron transport chain proteinscarbohydratesfats amino acids glucose fatty acids glycerol acetyl CoA Glycolysis pyruvate ATP Citric acid cycle

Photosynthesis vs. Cellular Respiration 30 Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display. O2O2 O2O2 enzymesgrana Photosynthesis NADP + CH 2 O NADPH CO 2 enzyme-catalyzed reactions NADH enzymes H2OH2O membrane ATP production via chemiosmosis ADP ATP H2OH2O membrane Cellular Respiration NAD + cristae CH 2 O CO 2