Introduction  In eukaryotes, cellular respiration –harvests energy from food, –yields large amounts of ATP, and –Uses ATP to drive cellular work.  A similar process takes place in many prokaryotic organisms. © 2012 Pearson Education, Inc.

Figure 6.0_1 Chapter 6: Big Ideas Cellular Respiration: Aerobic Harvesting of Energy Stages of Cellular Respiration Fermentation: Anaerobic Harvesting of Energy Connections Between Metabolic Pathways

6.1 Photosynthesis and cellular respiration provide energy for life  Life requires energy.  In almost all ecosystems, energy ultimately comes from the sun.  In photosynthesis, –some of the energy in sunlight is captured by chloroplasts, –atoms of carbon dioxide and water are rearranged, and –glucose and oxygen are produced. © 2012 Pearson Education, Inc.

Figure 6.1 Sunlight energy ECOSYSTEM Photosynthesis in chloroplasts Cellular respiration in mitochondria (for cellular work) Heat energy Glucose CO 2 H2OH2O O2O2 ATP

Figure 6.2 Breathing Lungs Bloodstream CO 2 O2O2 O2O2 Muscle cells carrying out Cellular Respiration Glucose  O 2 CO 2  H 2 O  ATP

Figure 6.3 Glucose OxygenWater Carbon dioxide C 6 H 12 O 6 O2O2 H2OH2O ATP6 6 6  Heat CO 2

6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen  Energy can be released from glucose by simply burning it.  The energy is dissipated as heat and light and is not available to living organisms. © 2012 Pearson Education, Inc.

6.5 Cells tap energy from electrons “falling” from organic fuels to oxygen  The movement of electrons from one molecule to another is an oxidation-reduction reaction, or redox reaction. In a redox reaction, –the loss of electrons from one substance is called oxidation, –the addition of electrons to another substance is called reduction, –a molecule is oxidized when it loses one or more electrons, and –reduced when it gains one or more electrons. © 2012 Pearson Education, Inc.

Figure 6.5A Glucose  Heat C 6 H 12 O 6 O2O2 CO 2 H2OH2O ATP Loss of hydrogen atoms (becomes oxidized) Gain of hydrogen atoms (becomes reduced)

Figure 6.5C Controlled release of energy for synthesis of ATP NADH NAD  HH HH O2O2 H2OH2O ATP Electron transport chain 2 1

6.6 Overview: Cellular respiration occurs in three main stages  Cellular respiration consists of a sequence of steps that can be divided into three stages. –Stage 1 – Glycolysis –Stage 2 – Pyruvate oxidation and citric acid cycle –Stage 3 – Oxidative phosphorylation © 2012 Pearson Education, Inc.

6.6 Overview: Cellular respiration occurs in three main stages  Stage 1: Glycolysis –occurs in the cytoplasm, –begins cellular respiration, and –breaks down glucose into two molecules of a three- carbon compound called pyruvate. © 2012 Pearson Education, Inc.

6.6 Overview: Cellular respiration occurs in three main stages  Stage 2: The citric acid cycle –takes place in mitochondria, –oxidizes pyruvate to a two-carbon compound, and –supplies the third stage with electrons. © 2012 Pearson Education, Inc.

6.6 Overview: Cellular respiration occurs in three main stages  Stage 3: Oxidative phosphorylation –involves electrons carried by NADH and FADH 2, –shuttles these electrons to the electron transport chain embedded in the inner mitochondrial membrane, –involves chemiosmosis, and –generates ATP through oxidative phosphorylation associated with chemiosmosis. © 2012 Pearson Education, Inc.

Figure 6.6_1 NADH FADH 2 ATP CYTOPLASM Glycolysis Electrons carried by NADH Glucose Pyruvate Pyruvate Oxidation Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Mitochondrion Substrate-level phosphorylation Oxidative phosphorylation

Figure 6.7Ca_s1 Glucose Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate ENERGY INVESTMENT PHASE PP P P ADP ATP Step Steps – A fuel molecule is energized, using ATP

Figure 6.7Ca_s2 Glucose Glucose 6-phosphate Fructose 6-phosphate Fructose 1,6-bisphosphate Glyceraldehyde 3-phosphate (G3P) ENERGY INVESTMENT PHASE P P PP P P ADP ATP Step Steps – A fuel molecule is energized, using ATP. Step A six-carbon intermediate splits into two three-carbon intermediates

Figure 6.7Cb_s1 555 Step A redox reaction generates NADH. ENERGY PAYOFF PHASE 1,3-Bisphospho- glycerate NADH NAD  HH HH P P P P P P P P

Figure 6.7Cb_s Step A redox reaction generates NADH. Steps – ATP and pyruvate are produced. ENERGY PAYOFF PHASE 1,3-Bisphospho- glycerate 3-Phospho- glycerate 2-Phospho- glycerate Phosphoenol- pyruvate (PEP) Pyruvate NADH NAD  HH HH ADP ATP H2OH2O H2OH2O P P P P P P P P P P P P P P

Figure 6.8 Pyruvate Coenzyme A Acetyl coenzyme A NAD  NADHHH CoA CO

Figure 6.9A Acetyl CoA Citric Acid Cycle CoA CO NAD  3 H  NADH ADP ATP P FAD FADH 2

Figure 6.9B_s3 NADH NAD  NADH HH HH HH CO 2 ATP ADP P FAD FADH 2 CoA Acetyl CoA Oxaloacetate Citric Acid Cycle 2 carbons enter cycle Citrate leaves cycle Alpha-ketoglutarate leaves cycle Succinate Malate Step Acetyl CoA stokes the furnace. Steps – NADH, ATP, and CO 2 are generated during redox reactions. Steps – Further redox reactions generate FADH 2 and more NADH.

Figure 6.10_1 HH HH HH HH HH HH HH HH HH HH HH Oxidative Phosphorylation Electron Transport Chain Chemiosmosis I II III IV NADH NAD  2 H  FADH 2 FAD O2O2 H2OH2O ADP PATP 2 1 Electron flow Protein complex of electron carriers Mobile electron carriers ATP synthase

6.12 Review: Each molecule of glucose yields many molecules of ATP  Recall that the energy payoff of cellular respiration involves 1.glycolysis, 2.alteration of pyruvate, 3.the citric acid cycle, and 4.oxidative phosphorylation. © 2012 Pearson Education, Inc.

Figure 6.12 NADH FADH 2 NADH FADH 2 NADH or NADH Mitochondrion CYTOPLASM Electron shuttles across membrane Glycolysis Glucose 2 Pyruvate Pyruvate Oxidation 2 Acetyl CoA Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Maximum per glucose: by substrate-level phosphorylation by oxidative phosphorylation ATP  2 about  28 ATP About ATP32ATP  2

© 2012 Pearson Education, Inc. Animation: Fermentation Overview Right click on animation / Click play

Figure 6.13A 2 NAD  2 NADH 2 NAD  2 NADH 2 Lactate 2 Pyruvate Glucose 2 ADP 2 ATP 2 P Glycolysis

Figure 6.13B 2 NAD  2 NADH 2 NAD  2 NADH 2 Ethanol 2 Pyruvate Glucose 2 ADP 2 ATP 2 P Glycolysis 2 CO 2

6.14 EVOLUTION CONNECTION: Glycolysis evolved early in the history of life on Earth  The ancient history of glycolysis is supported by its –occurrence in all the domains of life and –location within the cell, using pathways that do not involve any membrane-bounded organelles. © 2012 Pearson Education, Inc.

CONNECTIONS BETWEEN METABOLIC PATHWAYS © 2012 Pearson Education, Inc.

6.15 Cells use many kinds of organic molecules as fuel for cellular respiration  Although glucose is considered to be the primary source of sugar for respiration and fermentation, ATP is generated using –carbohydrates, –fats, and –proteins. © 2012 Pearson Education, Inc.

Figure 6.15 Food, such as peanuts Sugars Glycerol Fatty acidsAmino acids Amino groups Oxidative Phosphorylation Citric Acid Cycle Pyruvate Oxidation Acetyl CoA ATP Glucose G3PPyruvate Glycolysis Carbohydrates Fats Proteins

Figure 6.16 Carbohydrates Fats Proteins Cells, tissues, organisms Amino acids Fatty acids Glycerol Sugars Amino groups Citric Acid Cycle Pyruvate Oxidation Acetyl CoA ATP needed to drive biosynthesis ATP Glucose Synthesis Pyruvate G3PGlucose

You should now be able to 1.Compare the processes and locations of cellular respiration and photosynthesis. 2.Explain how breathing and cellular respiration are related. 3.Provide the overall chemical equation for cellular respiration. 4.Explain how the human body uses its daily supply of ATP. © 2012 Pearson Education, Inc.

You should now be able to 5.Explain how the energy in a glucose molecule is released during cellular respiration. 6.Explain how redox reactions are used in cellular respiration. 7.Describe the general roles of dehydrogenase, NADH, and the electron transport chain in cellular respiration. 8.Compare the reactants, products, and energy yield of the three stages of cellular respiration. © 2012 Pearson Education, Inc.

You should now be able to 9.Explain how rotenone, cyanide, carbon monoxide, oligomycin, and uncouplers interrupt critical events in cellular respiration. 10.Compare the reactants, products, and energy yield of alcohol and lactic acid fermentation. 11.Distinguish between strict anaerobes and facultative anaerobes. 12.Explain how carbohydrates, fats, and proteins are used as fuel for cellular respiration. © 2012 Pearson Education, Inc.

Figure 6.UN01 Substrate- level phosphorylation Oxidative phosphorylation ATP NADH FADH 2 Mitochondrion Glycolysis Pyruvate Oxidation Citric Acid Cycle Oxidative Phosphorylation (electron transport and chemiosmosis) Electrons carried by NADH Glucose Pyruvate CYTOPLASM

Figure 6.UN02 cellular work chemiosmosis H  gradient glucose and organic fuels Cellular respiration generates has three stagesoxidizes uses produce some produces many to pull electrons down H  diffuse through ATP synthase pumps H  to create uses by a process called energy for (a) (b) (c) (d) (e) (f) (g) to