1. © 2010 Pearson Education, Inc. Lectures by Chris C. Romero, updated by Edward J. Zalisko PowerPoint ® Lectures for Campbell Essential Biology, Fourth Edition – Eric Simon, Jane Reece, and Jean Dickey Campbell Essential Biology with Physiology, Third Edition – Eric Simon, Jane Reece, and Jean Dickey Chapter 6 Cellular Respiration: Obtaining Energy from Food

2. © 2010 Pearson Education, Inc. Biology and Society: Marathoners versus Sprinters Sprinters do not usually compete at short and long distances. Natural differences in the muscles of these athletes favor sprinting or long-distance running.

3. Figure 6.00

4. © 2010 Pearson Education, Inc. The muscles that move our legs contain two main types of muscle fibers: –Slow twitch –Fast twitch

5. © 2010 Pearson Education, Inc. Slow-twitch fibers: –Generate less power –Last longer –Generate ATP using oxygen

6. © 2010 Pearson Education, Inc. Fast-twitch fibers: –Generate more power –Fatigue much more quickly –Can generate ATP without using oxygen All human muscles contain both types of fibers but in different ratios.

7. ENERGY FLOW AND CHEMICAL CYCLING IN THE BIOSPHERE Animals depend on plants to convert solar energy to: –Chemical energy of sugars –Other molecules we consume as food © 2010 Pearson Education, Inc.

8. Photosynthesis: –Uses light energy from the sun to power a chemical process that makes organic molecules. © 2010 Pearson Education, Inc.

9. Producers and Consumers Plants and other autotrophs (self-feeders): –Make their own organic matter from inorganic nutrients. Heterotrophs (other-feeders): –Include humans and other animals that cannot make organic molecules from inorganic ones.

10. © 2010 Pearson Education, Inc. Autotrophs are producers because ecosystems depend upon them for food. Heterotrophs are consumers because they eat plants or other animals.

11. Figure 6.1

12. Chemical Cycling between Photosynthesis and Cellular Respiration The ingredients for photosynthesis are carbon dioxide and water. –CO 2 is obtained from the air by a plant’s leaves. –H 2 O is obtained from the damp soil by a plant’s roots. © 2010 Pearson Education, Inc.

13. Chloroplasts in the cells of leaves: –Use light energy to rearrange the atoms of CO 2 and H 2 O, which produces –Sugars (such as glucose) –Other organic molecules –Oxygen © 2010 Pearson Education, Inc.

14. Plant and animal cells perform cellular respiration, a chemical process that: –Primarily occurs in mitochondria –Harvests energy stored in organic molecules –Uses oxygen –Generates ATP

15. © 2010 Pearson Education, Inc. The waste products of cellular respiration are: –CO 2 and H 2 O –Used in photosynthesis

16. © 2010 Pearson Education, Inc. Animals perform only cellular respiration. Plants perform: –Photosynthesis and –Cellular respiration

17. Sunlight energy enters ecosystem Photosynthesis Cellular respiration C 6 H 12 O 6 Glucose O 2 Oxygen CO 2 Carbon dioxide H 2 O Water drives cellular work Heat energy exits ecosystem ATP Figure 6.2

18. CELLULAR RESPIRATION: AEROBIC HARVEST OF FOOD ENERGY Cellular respiration is: –The main way that chemical energy is harvested from food and converted to ATP –An aerobic process—it requires oxygen © 2010 Pearson Education, Inc.

19. Cellular respiration and breathing are closely related. –Cellular respiration requires a cell to exchange gases with its surroundings. –Cells take in oxygen gas. –Cells release waste carbon dioxide gas. –Breathing exchanges these same gases between the blood and outside air. © 2010 Pearson Education, Inc.

20. Breathing Cellular respiration Muscle cells Lungs CO 2 O2O2 O2O2 Figure 6.3

21. Breathing Cellular respiration Muscle cells Lungs CO 2 O2O2 O2O2 Figure 6.3a

22. Figure 6.3b

23. © 2010 Pearson Education, Inc. The Overall Equation for Cellular Respiration A common fuel molecule for cellular respiration is glucose. The overall equation for what happens to glucose during cellular respiration:

24. C 6 H 12 O 6 CO 2 O2O2 H2OH2O GlucoseOxygenCarbon dioxide Water  6 6 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) Figure 6.UN02

25. © 2010 Pearson Education, Inc. The Role of Oxygen in Cellular Respiration Cellular respiration can produce up to 38 ATP molecules for each glucose molecule consumed. During cellular respiration, hydrogen and its bonding electrons change partners. –Hydrogen and its electrons go from sugar to oxygen, forming water. –This hydrogen transfer is why oxygen is so vital to cellular respiration.

26. © 2010 Pearson Education, Inc. Redox Reactions Chemical reactions that transfer electrons from one substance to another are called: –Oxidation-reduction reactions or –Redox reactions for short

27. © 2010 Pearson Education, Inc. The loss of electrons during a redox reaction is called oxidation. The acceptance of electrons during a redox reaction is called reduction.

28. © 2010 Pearson Education, Inc. During cellular respiration glucose is oxidized while oxygen is reduced.

29. Citric Acid Cycle Electron Transport Glycolysis ATP Figure 6.UN03

30. © 2010 Pearson Education, Inc. Why does electron transfer to oxygen release energy? –When electrons move from glucose to oxygen, it is as though the electrons were falling. –This “fall” of electrons releases energy during cellular respiration.

31. Release of heat energy 1 2 H2H2 O2O2 H2OH2O Figure 6.4

32. © 2010 Pearson Education, Inc. Cellular respiration is: –A controlled fall of electrons –A stepwise cascade much like going down a staircase

33. © 2010 Pearson Education, Inc. NADH and Electron Transport Chains The path that electrons take on their way down from glucose to oxygen involves many steps.

34. © 2010 Pearson Education, Inc. The first step is an electron acceptor called NAD +. –The transfer of electrons from organic fuel to NAD + reduces it to NADH. The rest of the path consists of an electron transport chain, which: –Involves a series of redox reactions –Ultimately leads to the production of large amounts of ATP

35. Electrons from food Stepwise release of energy used to make Hydrogen, electrons, and oxygen combine to produce water Electron transport chain NADH NAD  HH HH ATP H2OH2O O2O2 22 2 2 2 1 ee ee ee ee ee ee Figure 6.5

36. © 2010 Pearson Education, Inc. An Overview of Cellular Respiration Cellular respiration: –Is an example of a metabolic pathway, which is a series of chemical reactions in cells All of the reactions involved in cellular respiration can be grouped into three main stages: –Glycolysis –The citric acid cycle –Electron transport

37. Cytoplasm Animal cellPlant cell Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid ATP Figure 6.6

38. Cytoplasm Mitochondrion High-energy electrons carried by NADH High-energy electrons carried mainly by NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid ATP Figure 6.6a

39. © 2010 Pearson Education, Inc. The Three Stages of Cellular Respiration With the big-picture view of cellular respiration in mind, let’s examine the process in more detail.

40. © 2010 Pearson Education, Inc. Stage 1: Glycolysis A six-carbon glucose molecule is split in half to form two molecules of pyruvic acid. These two molecules then donate high energy electrons to NAD +, forming NADH.

41. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUTOUTPUT Figure 6.7-1

42. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUTOUTPUT Energy harvest phase NADH NAD  Figure 6.7-2

43. Energy investment phase Carbon atom Phosphate group High-energy electron Key Glucose 2 ATP 2 ADP INPUTOUTPUT Energy harvest phase NADH NAD  2 ATP 2 ADP 2 Pyruvic acid Figure 6.7-3

44. © 2010 Pearson Education, Inc. Glycolysis: –Uses two ATP molecules per glucose to split the six-carbon glucose –Makes four additional ATP directly when enzymes transfer phosphate groups from fuel molecules to ADP Thus, glycolysis produces a net of two molecules of ATP per glucose molecule.

45. ADP ATP P PP Enzyme Figure 6.8

46. © 2010 Pearson Education, Inc. Stage 2: The Citric Acid Cycle The citric acid cycle completes the breakdown of sugar.

47. © 2010 Pearson Education, Inc. In the citric acid cycle, pyruvic acid from glycolysis is first “prepped.”

48. (from glycolysis)(to citric acid cycle) Oxidation of the fuel generates NADH Pyruvic acid loses a carbon as CO 2 Acetic acid attaches to coenzyme A Pyruvic acid Acetic acid Acetyl CoA Coenzyme A CoA CO 2 NAD  NADH INPUTOUTPUT Figure 6.9

49. © 2010 Pearson Education, Inc. The citric acid cycle: –Extracts the energy of sugar by breaking the acetic acid molecules all the way down to CO 2 –Uses some of this energy to make ATP –Forms NADH and FADH 2 Blast Animation: Harvesting Energy: Krebs Cycle

50. 3 NAD  ADP  P 3 NADH FADH 2 FAD Acetic acid Citric acid Acceptor molecule Citric Acid Cycle ATP 2 CO 2 INPUT OUTPUT Figure 6.10

51. © 2010 Pearson Education, Inc. Stage 3: Electron Transport Electron transport releases the energy your cells need to make the most of their ATP.

52. © 2010 Pearson Education, Inc. The molecules of the electron transport chain are built into the inner membranes of mitochondria. –The chain functions as a chemical machine that uses energy released by the “fall” of electrons to pump hydrogen ions across the inner mitochondrial membrane. –These ions store potential energy.

53. © 2010 Pearson Education, Inc. When the hydrogen ions flow back through the membrane, they release energy. –The hydrogen ions flow through ATP synthase. –ATP synthase: –Takes the energy from this flow –Synthesizes ATP

54. Space between membranes Inner mitochondrial membrane Electron carrier Protein complex Electron flow MatrixElectron transport chain ATP synthase NADH NAD  FADH 2 FAD ATP ADP  H2OH2O O2O2 HH 1 2 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 HH  2 P Figure 6.11

55. 1 2 Space between membranes Inner mitochondrial membrane Electron carrier Protein complex Electron flow MatrixElectron transport chain ATP synthase NADH NAD  FADH 2 FAD ATP ADP H2OH2O O2O2 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 HH HH  2 P  Figure 6.11a

56. © 2010 Pearson Education, Inc. Cyanide is a deadly poison that: –Binds to one of the protein complexes in the electron transport chain –Prevents the passage of electrons to oxygen –Stops the production of ATP

57. © 2010 Pearson Education, Inc. The Versatility of Cellular Respiration In addition to glucose, cellular respiration can “burn”: –Diverse types of carbohydrates –Fats –Proteins

58. Food PolysaccharidesFatsProteins SugarsGlycerolFatty acidsAmino acids Glycolysis Acetyl CoA Citric Acid Cycle Electron Transport ATP Figure 6.12

59. © 2010 Pearson Education, Inc. Adding Up the ATP from Cellular Respiration Cellular respiration can generate up to 38 molecules of ATP per molecule of glucose.

60. Cytoplasm Mitochondrion NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid 2 ATP 2 ATP NADH FADH 2 Maximum per glucose: 2 Acetyl CoA About 34 ATP by direct synthesis by direct synthesis by ATP synthase 22 2 6 About 38 ATP Figure 6.13

61. © 2010 Pearson Education, Inc. FERMENTATION: ANAEROBIC HARVEST OF FOOD ENERGY Some of your cells can actually work for short periods without oxygen. Fermentation is the anaerobic (without oxygen) harvest of food energy.

62. © 2010 Pearson Education, Inc. Fermentation in Human Muscle Cells After functioning anaerobically for about 15 seconds: –Muscle cells will begin to generate ATP by the process of fermentation Fermentation relies on glycolysis to produce ATP.

63. © 2010 Pearson Education, Inc. Glycolysis: –Does not require oxygen –Produces two ATP molecules for each glucose broken down to pyruvic acid

64. © 2010 Pearson Education, Inc. Pyruvic acid, produced by glycolysis, is –Reduced by NADH, producing NAD +, which keeps glycolysis going. In human muscle cells, lactic acid is a by-product. Animation: Fermentation Overview

65. Glucose 2 ATP 2 NAD  2 NADH 2 NAD   2 H  2 ADP 2 Pyruvic acid 2 Lactic acid Glycolysis INPUTOUTPUT  2 P Figure 6.14

66. Glucose 2 ATP 2 NAD  2 NADH 2 NAD   2 2 ADP 2 Pyruvic acid 2 Lactic acid Glycolysis INPUT OUTPUT  2 P HH Figure 6.14a

67. Figure 6.14b

68. © 2010 Pearson Education, Inc. Observation: Muscles produce lactic acid under anaerobic conditions. Question: Does the buildup of lactic acid cause muscle fatigue? Hypothesis: The buildup of lactic acid would cause muscle activity to stop. Experiment: Tested frog muscles under conditions when lactic acid could and could not diffuse away. The Process of Science: Does Lactic Acid Buildup Cause Muscle Burn?

69. Battery Force measured Battery Force measured Frog muscle stimulated by electric current Solution prevents diffusion of lactic acid Solution allows diffusion of lactic acid; muscle can work for twice as long Figure 6.15

70. © 2010 Pearson Education, Inc. Results: When lactic acid could diffuse away, performance improved greatly. Conclusion: Lactic acid accumulation is the primary cause of failure in muscle tissue. However, recent evidence suggests that the role of lactic acid in muscle function remains unclear.

71. © 2010 Pearson Education, Inc. Fermentation in Microorganisms Fermentation alone is able to sustain many types of microorganisms. The lactic acid produced by microbes using fermentation is used to produce: –Cheese, sour cream, and yogurt dairy products –Soy sauce, pickles, olives –Sausage meat products

72. © 2010 Pearson Education, Inc. Yeast are a type of microscopic fungus that: –Use a different type of fermentation –Produce CO 2 and ethyl alcohol instead of lactic acid This type of fermentation, called alcoholic fermentation, is used to produce: –Beer –Wine –Breads

73. Glucose 2 ATP 2 NAD  2 NADH 2 NAD   2  2 P 2 Pyruvic acid 2 Ethyl alcohol Glycolysis INPUTOUTPUT 2 CO 2 released Bread with air bubbles produced by fermenting yeast Beer fermentation 2 ADP HH Figure 6.16

74. Glucose 2 ATP 2 NAD  2 NADH 2 NAD   2 2 ADP 2 Pyruvic acid 2 Ethyl alcohol Glycolysis INPUTOUTPUT 2 CO 2 released  2 P HH Figure 6.16a

75. Figure 6.16b

76. Evolution Connection: Life before and after Oxygen Glycolysis could be used by ancient bacteria to make ATP when little oxygen was available, and before organelles evolved. © 2010 Pearson Education, Inc.

77. Today, glycolysis: –Occurs in almost all organisms –Is a metabolic heirloom of the first stage in the breakdown of organic molecules © 2010 Pearson Education, Inc.

78. O 2 present in Earth’s atmosphere First eukaryotic organisms Origin of Earth Atmospheric oxygen reaches 10% of modern levels Atmospheric oxygen first appears Oldest prokaryotic fossils Billions of years ago 2.1 0 2.7 4.5 2.2 3.5 Figure 6.17

79. O 2 present in Earth’s atmosphere First eukaryotic organisms Origin of Earth Atmospheric oxygen reaches 10% of modern levels Atmospheric oxygen first appears Oldest prokaryotic fossils Billions of years ago 2.1 0 2.7 4.5 2.2 3.5 Figure 6.17a

80. Figure 6.17b

81. C 6 H 12 O 6 CO 2 ATP O2O2 H2OH2O Glucose Oxygen Carbon dioxide WaterEnergy  6 6  6 6 6  Figure 6.UN01

82. C 6 H 12 O 6 CO 2 O2O2 H2OH2O GlucoseOxygenCarbon dioxide Water  6 6 Reduction Oxidation Oxygen gains electrons (and hydrogens) Glucose loses electrons (and hydrogens) Figure 6.UN02

83. Citric Acid Cycle Electron Transport Glycolysis ATP Figure 6.UN03

84. Citric Acid Cycle Electron Transport Glycolysis ATP Figure 6.UN04

85. Citric Acid Cycle Electron Transport Glycolysis ATP Figure 6.UN05

86. C 6 H 12 O 6 CO 2 H2OH2O ATP O2O2 Heat Photosynthesis Sunlight Cellular respiration Figure 6.UN06

87. C 6 H 12 O 6 CO 2 ATP O2O2 H2OH2O  6 6  6 6 6  Approx. 38 Figure 6.UN07

88. C 6 H 12 O 6 CO 2 ATP O2O2 H2OH2O Oxidation Glucose loses electrons (and hydrogens) Reduction Oxygen gains electrons (and hydrogens) Electrons (and hydrogens) Figure 6.UN08

89. NADH Citric Acid Cycle Electron Transport Glycolysis Glucose 2 Pyruvic acid 2 ATP 2 ATP NADH FADH 2 2 Acetyl CoA About 34 ATP by direct synthesis by direct synthesis by ATP synthase 22 2 6 About 38 ATP 2 CO 2 O2O2 H2OH2O 4 Mitochondrion Figure 6.UN09