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Cellular Respiration Slide 1 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways 9-1 Chemical Pathways Food serves as a source of raw materials for the cells in the body and as a source of energy. Animal Cells Animal Mitochondrion Plant Plant Cells Copyright Pearson Prentice Hall Slide 2 of 39 End Show 9-1 Chemical Pathways Both plant and animal cells carry out the final stages of cellular respiration in the mitochondria. Animal Cells Outer membrane Intermembrane Mitochondrion space Inner membrane Matrix Plant Cells Copyright Pearson Prentice Hall Slide 3 of 39 End Show Chemical Energy and Food Chemical Energy and Food One gram of the sugar glucose (C6H12O6), when burned in the presence of oxygen, releases 3811 calories of heat energy. A calorie is the amount of energy needed to raise the temperature of 1 gram of water 1 degree Celsius. Slide 4 of 39 Copyright Pearson Prentice Hall End Show Overview of Cellular Respiration What is cellular respiration? Slide 5 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Overview of Cellular Respiration Electrons carried in NADH Electrons carried in NADH and FADH2 Pyruvic acid Glucose Glycolysis Cytoplasm Mitochondrion Slide 6 of 39 Copyright Pearson Prentice Hall End Show Overview of Cellular Respiration Cellular respiration is the process that releases energy by breaking down glucose and other food molecules in the presence of oxygen. 3 parts: Glycolysis Krebs Cycle Electron Transport Chain Copyright Pearson Prentice Hall Slide 7 of 39 End Show Overview of Cellular Respiration The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen + glucose → carbon dioxide + water + Energy Slide 8 of 39 Copyright Pearson Prentice Hall End Show Overview of Cellular Respiration Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Glycolysis Cytoplasm Mitochondrion Slide 9 of 39 Copyright Pearson Prentice Hall End Show Glycolysis What happens during the process of glycolysis? Slide 10 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Glycolysis ATP Production At the beginning of glycolysis, the cell uses up 2 molecules of ATP to start the reaction. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Slide 11 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Glycolysis When glycolysis is complete, 4 ATP molecules have been produced. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Slide 12 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Glycolysis This gives the cell a net gain of 2 ATP molecules. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2 Pyruvic acid Slide 13 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Glycolysis NADH Production One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD+ 2 Pyruvic acid Slide 14 of 39 Copyright Pearson Prentice Hall End Show 9-1 Chemical Pathways Glycolysis Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule. 2 ATP 2 ADP 4 ADP 4 ATP Glucose 2NAD+ 2 2 Pyruvic acid Slide 15 of 39 Copyright Pearson Prentice Hall End Show Glycolysis The NADH molecule holds the electrons until they can be transferred to other molecules. 2 ATP 2 ADP 4 ADP 2NAD+ 4 ATP 2 2 Pyruvic acid To the electron transport chain Copyright Pearson Prentice Hall Slide 16 of 39 End Show Glycolysis The Advantages of Glycolysis The process of glycolysis is so fast that cells can produce thousands of ATP molecules in a few milliseconds. Glycolysis does not require oxygen. Slide 17 of 39 Copyright Pearson Prentice Hall End Show 9-2 The Krebs Cycle and Electron Transport Oxygen is required for the final steps of cellular respiration. Because the pathways of cellular respiration require oxygen, they are aerobic. Slide 18 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle What happens during the Krebs cycle? Slide 19 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energyextracting reactions. Slide 20 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle The Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion. Slide 21 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle One carbon molecule is removed, forming CO2, and electrons are removed, changing NAD+ to NADH. Slide 22 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle Coenzyme A joins the 2-carbon molecule, forming acetyl-CoA. Slide 23 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle Acetyl-CoA then adds the 2-carbon acetyl group to a 4carbon compound, forming citric acid. Citric acid Slide 24 of 39 Copyright Pearson Prentice Hall End Show Citric acid is broken down into a 5-carbon compound, then into a 4-carbon compound. The Krebs Cycle Slide 25 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle Two more molecules of CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2 Slide 26 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle In addition, one molecule of ATP is generated. Slide 27 of 39 Copyright Pearson Prentice Hall End Show The Krebs Cycle The energy tally from 1 molecule of pyruvic acid is • • • 4 NADH 1 FADH2 1 ATP Slide 28 of 39 Copyright Pearson Prentice Hall End Show Electron Transport How are high-energy electrons used by the electron transport chain? Slide 29 of 39 Copyright Pearson Prentice Hall End Show Electron Transport Electron Transport The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. Slide 30 of 39 Copyright Pearson Prentice Hall End Show Electron Transport High-energy electrons from NADH and FADH2 are passed along the electron transport chain from one carrier protein to the next. Slide 31 of 39 Copyright Pearson Prentice Hall End Show Electron Transport At the end of the chain, an enzyme combines these electrons with hydrogen ions and oxygen to form water. Slide 32 of 39 Copyright Pearson Prentice Hall End Show Electron Transport As the final electron acceptor of the electron transport chain, oxygen gets rid of the low-energy electrons and hydrogen ions. Slide 33 of 39 Copyright Pearson Prentice Hall End Show Electron Transport When 2 high-energy electrons move down the electron transport chain, their energy is used to move hydrogen ions (H+) across the membrane. Slide 34 of 39 Copyright Pearson Prentice Hall End Show Electron Transport During electron transport, H+ ions build up in the intermembrane space, so it is positively charged. Slide 35 of 39 Copyright Pearson Prentice Hall End Show Electron Transport The other side of the membrane, from which those H+ ions are taken, is now negatively charged. Slide 36 of 39 Copyright Pearson Prentice Hall End Show Electron Transport The inner membranes of the mitochondria contain protein spheres called ATP synthases. ATP synthase Slide 37 of 39 Copyright Pearson Prentice Hall End Show Electron Transport As H+ ions escape through channels into these proteins, the ATP synthase spins. Channel ATP synthase Slide 38 of 39 Copyright Pearson Prentice Hall End Show Electron Transport As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate, forming high-energy ATP. Channel ATP synthase ATP Slide 39 of 39 Copyright Pearson Prentice Hall End Show The Totals The Totals Glycolysis produces just 2 ATP molecules per molecule of glucose. The complete breakdown of glucose through cellular respiration, including glycolysis, results in the production of 36 molecules of ATP. Slide 40 of 39 Copyright Pearson Prentice Hall End Show The Totals Slide 41 of 39 Copyright Pearson Prentice Hall End Show Comparing Photosynthesis and Cellular Respiration Comparing Photosynthesis and Cellular Respiration The energy flows in photosynthesis and cellular respiration take place in opposite directions. Slide 42 of 39 Copyright Pearson Prentice Hall End Show Comparing Photosynthesis and Cellular Respiration On a global level, photosynthesis and cellular respiration are also opposites. • Photosynthesis removes carbon dioxide from the atmosphere and cellular respiration puts it back. • Photosynthesis releases oxygen into the atmosphere and cellular respiration uses that oxygen to release energy from food. Slide 43 of 39 Copyright Pearson Prentice Hall End Show • What happens when there is no oxygen present??? Slide 44 of 39 Copyright Pearson Prentice Hall End Show Fermentation Fermentation When oxygen is not present, glycolysis is followed by a different pathway. The combined process of this pathway and glycolysis is called fermentation. Fermentation releases energy from food molecules by producing ATP in the absence of oxygen. Slide 45 of 39 Copyright Pearson Prentice Hall End Show Common Foods that use fermentation • Coffee • Salami • Chocolate • Beer • Tea • Wine • Sourdough bread • Sauerkraut • Cheese • Pickles • Yogurt • vinegar Slide 46 of 39 Copyright Pearson Prentice Hall End Show Fermentation What are the two main types of fermentation? Slide 47 of 39 Copyright Pearson Prentice Hall End Show Alcoholic Fermentation Yeasts and a few other microorganisms use alcoholic fermentation, forming ethyl alcohol and carbon dioxide as wastes. The equation for alcoholic fermentation after glycolysis is: pyruvic acid + NADH → alcohol + CO2 + NAD+ Slide 48 of 39 Copyright Pearson Prentice Hall End Show Slide 49 of 39 Copyright Pearson Prentice Hall End Show Slide 50 of 39 Copyright Pearson Prentice Hall End Show Fermentation Lactic Acid Fermentation In many cells, pyruvic acid that accumulates as a result of glycolysis can be converted to lactic acid. This type of fermentation is called lactic acid fermentation. It regenerates NAD+ so that glycolysis can continue. The equation for lactic acid fermentation after glycolysis is: Slide 51 of 39 pyruvic acid + NADH → lactic acid + NAD+End Show Copyright Pearson Prentice Hall • Lactic acid build up in the muscles causes a burning sensation – caused by the lack of Oxygen Slide 52 of 39 Copyright Pearson Prentice Hall End Show Slide 53 of 39 Copyright Pearson Prentice Hall End Show