Slide 1 CHAPTER 6 Cellular Respiration: Harvesting Chemical Energy PowerPoint Lecture Slides for Essential Biology, Second Edition & Essential Biology with Physiology Presentation prepared by Chris C. Romero Copyright 2004 Pearson Education, Inc. publishing as Benjamin Cummings Neil Campbell, Jane Reece, and Eric Simon Slide 2 BIOLOGY AND SOCIETY: FEELING THE BURN When you exercise Muscles need energy in order to perform work Your cells use oxygen to release energy from the sugar glucose Slide 3 Aerobic metabolism Anaerobic metabolism
Slide 4 Physical conditioning allows your body to adapt to increased activity Long-distance runners wait until the final sprint to exceed their aerobic capacity Figure 6.1 Slide 5 ENERGY FLOW AND CHEMICAL CYCLING IN THE BIOSPHERE Fuel molecules in food represent solar energy Animals depend on plants to convert solar energy to chemical energy Slide 6 Producers and Consumers Photosynthesis
Slide 7 Autotrophs Heterotrophs Slide 8 Producers Consumers Figure 6.2 Slide 9 Chemical Cycling Between Photosynthesis and Cellular Respiration The ingredients for photosynthesis are carbon dioxide and water Chloroplasts rearrange the atoms of these ingredients to produce sugars (glucose) and other organic molecules
Slide 10 Key Products of Photosynthesis Glucose Oxygen Slide 11 Both plants and animals perform cellular respiration The waste products of cellular respiration, CO 2 and H 2 O, are used in photosynthesis Slide 12 Sunlight energy Ecosystem Photosynthesis (in chloroplasts) Glucose Carbon dioxide Oxygen Water Cellular respiration (in mitochondria) for cellular work Heat energy Figure 6.3
Slide 13 CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY Cellular respiration Slide 14 The Relationship Between Cellular Respiration and Breathing Cellular respiration and breathing are closely related Slide 15 Breathing Lungs Muscle cells Cellular respiration Figure 6.4
Slide 16 The Overall Equation for Cellular Respiration A common fuel molecule for cellular respiration is glucose Glucose Oxygen Carbon dioxide Water Energy Unnumbered Figure 6.1 Slide 17 The Role of Oxygen in Cellular Respiration During cellular respiration, hydrogen and its bonding electrons change partners Slide 18 Redox Reactions Chemical reactions that transfer electrons from one substance to another are called oxidation-reduction reactions
Slide 19 The loss of electrons during a redox reaction is called oxidation The acceptance of electrons during a redox reaction is called reduction Slide 20 Oxidation [Glucose loses electrons (and hydrogens)] Glucose Oxygen Carbon dioxide Water Reduction [Oxygen gains electrons (and hydrogens)] Unnumbered Figure 6.2 Slide 21 Why does electron transfer to oxygen release energy? Release of heat energy Figure 6.5
Slide 22 NADH and Electron Transport Chains The path that electrons take on their way down from glucose to oxygen involves many stops (from food via NADH) Energy for 2 H + 2 e synthesis of Electron transport chain 1 / 2 2 e 2 H + 1 / 2 Figure 6.6 Slide 23 The first stop is an electron acceptor called NAD + The rest of the path consists of an electron transport chain Slide 24 The Metabolic Pathway of Cellular Respiration Cellular respiration is an example of a metabolic pathway All of the reactions involved in cellular respiration can be grouped into three main stages
Slide 25 A Road Map for Cellular Respiration Cytosol High-energy electrons carried by NADH Mitochondrion High-energy electrons carried mainly by NADH Glycolysis 2 Glucose Pyruvic acid Krebs Cycle Electron Transport Figure 6.7 Slide 26 Stage 1: Glycolysis A molecule of glucose is split into two molecules of pyruvic acid Slide 27 Glycolysis breaks a six-carbon glucose into two three-carbon molecules
Slide 28 2 Pyruvic acid Glucose Figure 6.8 Slide 29 Glycolysis makes some ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP Enzyme Figure 6.9 Slide 30 Stage 2: The Krebs Cycle The Krebs cycle completes the breakdown of sugar
Slide 31 In the Krebs cycle, pyruvic acid from glycolysis is first prepped into a usable form, Acetyl-CoA CoA 2 Pyruvic acid 1 CO 2 Acetic acid 3 Coenzyme A Acetyl-CoA (acetyl-coenzyme A) Figure 6.10 Slide 32 The Krebs cycle extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO 2 Slide 33 Input Output 1 Acetic acid 2 CO 2 2 ADP 3 NAD + Krebs Cycle 3 4 FAD 5 6 Figure 6.11
Slide 34 Stage 3: Electron Transport Electron transport releases the energy your cells need to make the most of their ATP Slide 35 The molecules of electron transport chains are built into the inner membranes of mitochondria Slide 36 When the hydrogen ions flow back through the membrane, they release energy
Slide 37 Protein complex Electron carrier Inner mitochondrial membrane Electron flow Electron transport chain ATP synthase Figure 6.12 Slide 38 The Versatility of Cellular Respiration Cellular respiration can burn other kinds of molecules besides glucose Slide 39 Food Polysaccharides Fats Proteins Sugars Glycerol Fatty acids Amino acids Amino groups Glycolysis Acetyl- CoA Krebs Cycle Electron Transport Figure 6.13
Slide 40 Adding Up the ATP from Cellular Respiration Cytosol Mitochondrion Glycolysis 2 Glucose Pyruvic acid 2 Acetyl- CoA Krebs Cycle Electron Transport Maximum per glucose: by direct synthesis by direct synthesis by ATP synthase Figure 6.14 Slide 41 FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY Some of your cells can actually work for short periods without oxygen Fermentation Slide 42 Fermentation in Human Muscle Cells Human muscle cells can make ATP with and without oxygen
Slide 43 Glycolysis is the metabolic pathway that provides ATP during fermentation Slide 44 2 ADP+ 2 Glycolysis 2 NAD + 2 Pyruvic 2 NAD + Glucose acid + 2 H + 2 Lactic acid (a) Lactic acid fermentation Figure 6.15a Slide 45 Fermentation in Microorganisms Various types of microorganisms perform fermentation
Slide 46 2 ADP+ 2 2 ATP Glycolysis 2 CO 2 released Glucose 2 NAD + 2 Pyruvic acid + 2 H + 2 NAD + 2 Ethyl alcohol (b) Alcoholic fermentation Figure 6.15b Slide 47 The food industry uses yeast to produce various food products Figure 6.16 Slide 48 EVOLUTION CONNECTION: LIFE ON AN ANAEROBIC EARTH Ancient bacteria probably used glycolysis to make ATP long before oxygen was present in Earth s atmosphere Glycolysis is a metabolic heirloom from the earliest cells that continues to function today in the harvest of food energy
Chapter 6 Study Objectives 1. Explain why we breathe faster when we exercise. 2. Explain why an athlete switches from aerobic to anaerobic metabolism during strenuous exercise. 3. Explain why aerobic metabolism is better for an athlete than anaerobic metabolism. 4. Describe where photosynthesis occurs, and explain why this process is important to ecosystems. 5. Define and compare autotrophs and heterotrophs, producers and consumers. 6. Explain how the processes of photosynthesis and cellular respiration are complementary to each other. 7. Compare the processes of cellular respiration and breathing. 8. Write and explain the overall equation for cellular respiration. 9. Explain how the processes of oxidation and reduction are used to transfer electrons from food molecules to NADH, the electron transport chain, and oxygen. 10. Compare the reactants, products, and energy yield of the three stages of respiration (glycolysis, Krebs cycle, and electron transport chain), then indicate where each process occurs in the cell. 11. Compare the reactants, products, and energy yield of fermentation in human and yeast cells, then indicate where this process occurs in each type of cell. 12. Explain why it is likely that glycolysis is a primitive form of metabolism.