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Chapter Nine- Cellular Respiration & Fermentation

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Chapter nine lecture for Lab Bio

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Chapter Nine- Cellular Respiration & Fermentation

  1. 1. 9-1 Chemical Pathways Copyright Pearson Prentice Hall
  2. 2. Food serves as a source of raw materials for the cells in the body and as a source of energy. Copyright Pearson Prentice Hall Animal Plant Animal Cells Plant Cells Mitochondrion
  3. 3. Both plant and animal cells carry out cellular respiration in the mitochondria. Outer membrane Intermembrane Copyright Pearson Prentice Hall Animal Cells Plant Cells Mitochondrion space Inner membrane Matrix
  4. 4. 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. Copyright Pearson Prentice Hall
  5. 5. Cells don't “burn” glucose. Instead, they gradually release the energy from glucose and other food compounds. This process begins with a pathway called glycolysis. Glycolysis releases a small amount of energy. Copyright Pearson Prentice Hall
  6. 6. Overview of Cellular Respiration If oxygen is present, glycolysis is followed by the Krebs cycle and the electron transport chain. Glycolysis, the Krebs cycle, and the electron transport chain make up a process called cellular respiration. Copyright Pearson Prentice Hall
  7. 7. Overview of Cellular Respiration Electrons carried in NADH Copyright Pearson Prentice Hall Cytoplasm Pyruvic acid Electrons carried in NADH and FADH2 Mitochondrion Glucose Glycolysis
  8. 8. 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. Copyright Pearson Prentice Hall
  9. 9. The equation for cellular respiration is: 6O2 + C6H12O6 → 6CO2 + 6H2O + Energy oxygen glucose carbon water energy dioxide Copyright Pearson Prentice Hall
  10. 10. Each of the three stages of cellular respiration captures some of the chemical energy available in food molecules and uses it to produce ATP. Copyright Pearson Prentice Hall
  11. 11. Glycolysis takes place in the cytoplasm. The Krebs cycle and electron transport take place in the mitochondria. Copyright Pearson Prentice Hall Cytoplasm Mitochondrion Glycolysis
  12. 12. In glycolysis, one molecule of glucose is broken in half, producing two molecules of pyruvic acid. 2 ADP 4 ADP 4 ATP Copyright Pearson Prentice Hall 2 Pyruvic acid 2 ATP Glucose
  13. 13. Glycolysis requires 2 ATP to start the reaction. When glycolysis is complete, 4 ATP molecules have been produced. 2 ATP 2 ADP 4 ADP 4 ATP Copyright Pearson Prentice Hall Glucose 2 Pyruvic acid
  14. 14. Glycolysis gives the cell a net gain of 2 ATP molecules. Copyright Pearson Prentice Hall 4 ADP 4 ATP Glucose 2 ATP 2 ADP 2 Pyruvic acid
  15. 15. NADH Production One reaction of glycolysis removes 4 high-energy electrons, passing them to an electron carrier called NAD+. Copyright Pearson Prentice Hall Glucose 2 Pyruvic acid 2 ATP 2 ADP 4 ADP 4 ATP 2NAD+
  16. 16. Each NAD+ accepts a pair of high-energy electrons and becomes an NADH molecule. Copyright Pearson Prentice Hall Glucose 2 Pyruvic acid 2 ATP 2 ADP 4 ADP 4 ATP 2NAD+ 2
  17. 17. The NADH molecule holds high energy electrons until they can be transferred to other molecules. 2 ATP 2 ADP 4 ADP 4 ATP Copyright Pearson Prentice Hall 2NAD+ 2 Pyruvic acid 2 To the electron transport chain
  18. 18. 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. Copyright Pearson Prentice Hall
  19. 19. Glycolysis makes Krebs cycle and fermentation electron transport Copyright Pearson Prentice Hall With oxygen Without oxygen
  20. 20. 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. Copyright Pearson Prentice Hall
  21. 21. During fermentation, cells convert NADH to NAD+ by passing high-energy electrons back to pyruvic acid. This action converts NADH back into NAD+, and allows glycolysis to continue producing a steady supply of ATP. Fermentation does not require oxygen—it is an anaerobic process. Copyright Pearson Prentice Hall
  22. 22. The two main types of fermentation are lactic acid fermentation and alcoholic fermentation. Copyright Pearson Prentice Hall
  23. 23. Yeasts use alcoholic fermentation to get energy from pyruvic acid. Alcoholic fermentation forms ethanol and carbon dioxide as wastes. Copyright Pearson Prentice Hall
  24. 24. In lactic acid fermentation, the pyruvic acid and NADH from glycolysis are converted to lactic acid. It regenerates NAD+ so that glycolysis can continue. Copyright Pearson Prentice Hall
  25. 25. The first part of the equation is glycolysis. Copyright Pearson Prentice Hall
  26. 26. The second part shows the conversion of pyruvic acid to lactic acid. Copyright Pearson Prentice Hall
  27. 27. Energy needs are great when you exercise. If oxygen is limited, muscle cells will produce energy by lactic acid fermentation. Lactic acid buildup in muscles will cause soreness and cramps. Proper breathing will promote cellular respiration. Copyright Pearson Prentice Hall
  28. 28. 9-2 The Krebs Cycle and Electron Transport Copyright Pearson Prentice Hall
  29. 29. 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. Copyright Pearson Prentice Hall
  30. 30. In the presence of oxygen, pyruvic acid produced in glycolysis enters the Krebs cycle. Copyright Pearson Prentice Hall
  31. 31. The Krebs Cycle During the Krebs cycle, pyruvic acid is broken down into carbon dioxide in a series of energy-extracting reactions. Copyright Pearson Prentice Hall
  32. 32. The Krebs Cycle The Krebs cycle begins when pyruvic acid produced by glycolysis enters the mitochondrion. Copyright Pearson Prentice Hall
  33. 33. The Krebs Cycle One carbon is removed, forming CO2, and electrons are removed, changing NAD+ to NADH. Copyright Pearson Prentice Hall
  34. 34. The Krebs Cycle Coenzyme A joins the 2-carbon molecule, forming acetyl-CoA. Copyright Pearson Prentice Hall
  35. 35. The Krebs Cycle Copyright Pearson Prentice Hall Citric acid Acetyl-CoA then adds the 2- carbon acetyl group to a 4- carbon compound, forming citric acid.
  36. 36. Citric acid is broken down into a 5- carbon compound, then into a 4-carbon compound. Copyright Pearson Prentice Hall
  37. 37. Two more molecules of CO2 are released and electrons join NAD+ and FAD, forming NADH and FADH2 Copyright Pearson Prentice Hall
  38. 38. The Krebs Cycle In addition, one molecule of ATP is generated. Copyright Pearson Prentice Hall
  39. 39. The Krebs Cycle The energy tally from 1 molecule of pyruvic acid is • 4 NADH- electron carrier • 1 FADH2- electron carrier • 1 ATP- energy carrier Copyright Pearson Prentice Hall
  40. 40. The Krebs Cycle What does the cell do with all those high-energy electrons in carriers like NADH? In the electron transport chain, the high-energy electrons from NADH and FADH2 are used to generate huge amounts of ATP. Copyright Pearson Prentice Hall
  41. 41. Electron Transport Electron Transport The electron transport chain uses the high-energy electrons from the Krebs cycle to convert ADP into ATP. Copyright Pearson Prentice Hall
  42. 42. High-energy electrons from NADH and FADH2 are passed along the electron transport chain from one carrier protein to the next. Copyright Pearson Prentice Hall
  43. 43. Electron Transport At the end of the chain, an enzyme combines these electrons with hydrogen ions and oxygen to form water. Copyright Pearson Prentice Hall
  44. 44. As the final electron acceptor of the electron transport chain, oxygen gets rid of the low-energy electrons and hydrogen ions. Copyright Pearson Prentice Hall
  45. 45. When 2 high-energy electrons move down the electron transport chain, their energy is used to move hydrogen ions (H+) across the membrane. Copyright Pearson Prentice Hall
  46. 46. During electron transport, H+ ions build up in the intermembrane space, so it is positively charged. Copyright Pearson Prentice Hall
  47. 47. The other side of the membrane, from which those H+ ions are taken, is now negatively charged. Copyright Pearson Prentice Hall
  48. 48. The inner membranes of the mitochondria contain protein spheres called ATP synthases. Copyright Pearson Prentice Hall ATP synthase
  49. 49. As H+ ions escape through channels into these proteins, the ATP synthase spins. Copyright Pearson Prentice Hall Channel ATP synthase
  50. 50. As it rotates, the enzyme grabs a low-energy ADP, attaching a phosphate, forming high-energy Copyright Pearson Prentice Hall ATP. ATP Channel ATP synthase
  51. 51. On average, each pair of high-energy electrons that moves down the electron transport chain provides enough energy to produce three molecules of ATP from ADP. Copyright Pearson Prentice Hall
  52. 52. 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. Copyright Pearson Prentice Hall
  53. 53. The Totals Copyright Pearson Prentice Hall
  54. 54. Comparing Photosynthesis and Cellular Respiration Photosynthesis and cellular respiration are the same chemical reaction except in opposite directions. Copyright Pearson Prentice Hall
  55. 55. Comparing Photosynthesis and Cellular Respiration Same reaction flipped over! Photosynthesis + 6CO2 + 6H2O  C6H12O6 + 6O2 Cellular Respiration C6H12O6 + 6O2  6CO2 + 6H2O + Energy out Energy in
  56. 56. Photosynthesis in the chloroplast Only plants and algae have chloroplasts Cellular respiration in the mitochondria Almost all eukaryotes have mitochondriaC opyright Pearson Prentice Hall
  57. 57. 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. Copyright Pearson Prentice Hall
  58. 58. Copyright Pearson Prentice Hall 9-1 The raw materials required for cellular respiration are a. carbon dioxide and oxygen. b. glucose and water. c. glucose and oxygen. d. carbon dioxide and water.
  59. 59. Copyright Pearson Prentice Hall 9-1 Glycolysis occurs in the a. mitochondria. b. cytoplasm. c. nucleus. d. chloroplasts.
  60. 60. Copyright Pearson Prentice Hall 9-1 The net gain of ATP molecules after glycolysis is a. 3 ATP molecules. b. 2 ATP molecules. c. 3 pyruvic acid molecules. d. 4 pyruvic acid molecules
  61. 61. Copyright Pearson Prentice Hall 9-1 Fermentation releases energy from food molecules in the absence of a. oxygen. b. glucose. c. NADH. d. alcohol.
  62. 62. Copyright Pearson Prentice Hall 9-1 The first step in fermentation is always a. lactic acid production. b. the Krebs cycle. c. glycolysis. d. alcohol production.
  63. 63. Copyright Pearson Prentice Hall 9-2 The Krebs cycle breaks pyruvic acid down into a. oxygen. b. NADH. c. carbon dioxide. d. alcohol.
  64. 64. Copyright Pearson Prentice Hall 9-2 What role does the Krebs cycle play in the cell? a. It breaks down glucose and releases its stored energy. b. It releases energy from molecules formed during glycolysis. c. It combines carbon dioxide and water into high-energy molecules. d. It breaks down ATP and NADH, releasing stored energy.
  65. 65. Copyright Pearson Prentice Hall 9-2 In eukaryotes, the electron transport chain is located in the a. cell membrane. b. inner mitochondrial membrane. c. cytoplasm. d. outer mitochondrial membrane.
  66. 66. Copyright Pearson Prentice Hall 9-2 To generate energy over long periods, the body must use a. stored ATP. b. lactic acid fermentation. c. cellular respiration. d. glycolysis.
  67. 67. Copyright Pearson Prentice Hall 9-2 Which statement correctly describes photosynthesis and cellular respiration? a. Photosynthesis releases energy, while cellular respiration stores energy. b. Photosynthesis and cellular respiration use the same raw materials. c. Cellular respiration releases energy, while photosynthesis stores energy. d. Cellular respiration and photosynthesis produce the same products.

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