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 5 The Working Cell

2. Biology and Society: Natural Nanotechnology Cells control their chemical environment using –Energy –Enzymes –The plasma membrane Cell-based nanotechnology may be used to power microscopic robots. © 2010 Pearson Education, Inc.

3. Figure 5.00

4. © 2010 Pearson Education, Inc. SOME BASIC ENERGY CONCEPTS Energy makes the world go around. But what is energy?

5. © 2010 Pearson Education, Inc. Conservation of Energy Energy is defined as the capacity to perform work. Kinetic energy is the energy of motion. Potential energy is stored energy. Animation: Energy Concepts

6. Climbing the steps converts kinetic energy of muscle movement to potential energy. On the platform, the diver has more potential energy. Diving converts potential energy to kinetic energy. In the water, the diver has less potential energy. Figure 5.1

7. © 2010 Pearson Education, Inc. Machines and organisms can transform kinetic energy to potential energy and vice versa. In all such energy transformations, total energy is conserved. –Energy cannot be created or destroyed. –This is the principle of conservation of energy.

8. © 2010 Pearson Education, Inc. Entropy Every energy conversion releases some randomized energy in the form of heat. Heat is a –Type of kinetic energy –Product of all energy conversions

9. © 2010 Pearson Education, Inc. Scientists use the term entropy as a measure of disorder, or randomness. All energy conversions increase the entropy of the universe.

10. © 2010 Pearson Education, Inc. Chemical Energy Molecules store varying amounts of potential energy in the arrangement of their atoms. Organic compounds are relatively rich in such chemical energy.

11. © 2010 Pearson Education, Inc. Living cells and automobile engines use the same basic process to make chemical energy do work.

12. Fuel rich in chemical energy Energy conversion Waste products poor in chemical energy Gasoline  Oxygen Carbon dioxide  Water Energy conversion in a car Energy for cellular work Energy conversion in a cell Heat energy Heat energy Carbon dioxide  Water Food  Oxygen Combustion Cellular respiration Kinetic energy of movement ATP Figure 5.2

13. © 2010 Pearson Education, Inc. Cellular respiration is the energy-releasing chemical breakdown of fuel molecules that provides energy for cells to do work. Humans convert about 40% of the energy in food to useful work, such as the contraction of muscles.

14. © 2010 Pearson Education, Inc. Food Calories A calorie is the amount of energy that raises the temperature of one gram of water by 1 degree Celsius. Food Calories are kilocalories, equal to 1,000 calories.

15. (a) Food Calories (kilocalories) in various foods (b) Food Calories (kilocalories) we burn in various activities Cheeseburger Spaghetti with sauce (1 cup) Pizza with pepperoni (1 slice) Peanuts (1 ounce) Apple Bean burrito Fried chicken (drumstick) Garden salad (2 cups) Popcorn (plain, 1 cup) Broccoli (1 cup) Baked potato (plain, with skin) Food Calories Food 295 241 220 193 181 166 81 56 189 31 25 Activity Food Calories consumed per hour by a 150-pound person* 979 510 490 408 204 73 61 245 28 Running (7min/mi) Sitting (writing) Driving a car Playing the piano Dancing (slow) Walking (3 mph) Bicycling (10 mph) Swimming (2 mph) Dancing (fast) *Not including energy necessary for basic functions, such as breathing and heartbeat Figure 5.3

16. (a) Food Calories (kilocalories) in various foods Cheeseburger Spaghetti with sauce (1 cup) Pizza with pepperoni (1 slice) Peanuts (1 ounce) Apple Bean burrito Fried chicken (drumstick) Garden salad (2 cups) Popcorn (plain, 1 cup) Broccoli (1 cup) Baked potato (plain, with skin) Food CaloriesFood 295 241 220 193 181 166 81 56 189 31 25 Figure 5.3a

17. (b) Food Calories (kilocalories) we burn in various activities ActivityFood Calories consumed per hour by a 150-pound person* 979 510 490 408 204 73 61 245 28 Running (7min/mi) Sitting (writing) Driving a car Playing the piano Dancing (slow) Walking (3 mph) Bicycling (10 mph) Swimming (2 mph) Dancing (fast) *Not including energy necessary for basic functions, such as breathing and heartbeat Figure 5.3b

18. © 2010 Pearson Education, Inc. The energy of calories in food is burned off by many activities.

19. © 2010 Pearson Education, Inc. ATP AND CELLULAR WORK Chemical energy is –Released by the breakdown of organic molecules during cellular respiration –Used to generate molecules of ATP

20. © 2010 Pearson Education, Inc. ATP –Acts like an energy shuttle –Stores energy obtained from food –Releases it later as needed

21. © 2010 Pearson Education, Inc. The Structure of ATP ATP (adenosine triphosphate) –Consists of adenosine plus a tail of three phosphate groups –Is broken down to ADP and a phosphate group, releasing energy Blast Animation: Structure of ATP

22. TriphosphateDiphosphate Adenosine Energy ATPADP PPPPPP Phosphate (transferred to another molecule) Figure 5.4

23. © 2010 Pearson Education, Inc. Phosphate Transfer ATP energizes other molecules by transferring phosphate groups. This energy helps cells perform –Mechanical work –Transport work –Chemical work

24. ATP ADP P P P P P P P PXXY Y (a) Motor protein performing mechanical work (b) Transport protein performing transport work (c) Chemical reactants performing chemical work Solute Solute transported Protein moved Product madeReactants Transport protein Motor protein Figure 5.5

25. ATP ADPP P (a) Motor protein performing mechanical work Protein moved Motor protein Figure 5.5a

26. ATP ADPP P P (b) Transport protein performing transport work Solute Solute transported Transport protein Figure 5.5b

27. ATP ADPP P P X XY Y (c) Chemical reactants performing chemical work Product madeReactants Figure 5.5c

28. © 2010 Pearson Education, Inc. The ATP Cycle Cellular work spends ATP. ATP is recycled from ADP and a phosphate group through cellular respiration. A working muscle cell spends and recycles about 10 million ATP molecules per second. Blast Animation: ATP/ADP Cycle

29. Cellular respiration: chemical energy harvested from fuel molecules Energy for cellular work ATP ADP P Figure 5.6

30. © 2010 Pearson Education, Inc. ENZYMES Metabolism is the total of all chemical reactions in an organism. Most metabolic reactions require the assistance of enzymes, proteins that speed up chemical reactions.

31. © 2010 Pearson Education, Inc. Activation Energy Activation energy –Activates the reactants –Triggers a chemical reaction Enzymes lower the activation energy for chemical reactions. Blast Animation: How Enzymes Work: Activation Energy

32. (a) Without enzyme (b) With enzyme Reactant Products Activation energy barrier Activation energy barrier reduced by enzyme Enzyme Energy level Figure 5.7

33. (a) Without enzyme Reactant Products Activation energy barrier Energy level Figure 5.7a

34. (b) With enzyme Reactant Products Activation energy barrier reduced by enzyme Enzyme Energy level Figure 5.7b

35. The Process of Science: Can Enzymes Be Engineered? Observation: Genetic sequences suggest that many of our genes were formed through a type of molecular evolution. Question: Can laboratory methods form new enzymes through artificial selection? Hypothesis: An artificial process could modify the gene that codes for lactase into a new gene with a new function. © 2010 Pearson Education, Inc.

36. Experiment: Many copies of the lactase gene were randomly mutated and tested for new activities. Results: Directed evolution produced a new enzyme with a novel function. © 2010 Pearson Education, Inc.

37. Gene for lactase Mutated genes (mutations shown in orange) Mutated genes screened by testing new enzymes Gene duplicated and mutated at random Genes coding for enzymes that show new activity Genes coding for enzymes that do not show new activity Genes duplicated and mutated at random Mutated genes screened by testing new enzymes After seven rounds, some genes code for enzymes that can efficiently perform new activity. Ribbon model showing the polypeptide chains of the enzyme lactase Figure 5.8

38. Gene for lactase Mutated genes (mutations shown in orange) Mutated genes screened by testing new enzymes Gene duplicated and mutated at random Genes coding for enzymes that show new activity Genes coding for enzymes that do not show new activity Genes duplicated and mutated at random Mutated genes screened by testing new enzymes After seven rounds, some genes code for enzymes that can efficiently perform new activity. Figure 5.8a

39. Figure 5.8b Ribbon model showing the polypeptide chains of the enzyme lactase

40. © 2010 Pearson Education, Inc. Induced Fit Every enzyme is very selective, catalyzing a specific reaction.

41. © 2010 Pearson Education, Inc. Each enzyme recognizes a substrate, a specific reactant molecule. –The active site fits to the substrate, and the enzyme changes shape slightly. –This interaction is called induced fit.

42. © 2010 Pearson Education, Inc. Enzymes can function over and over again, a key characteristic of enzymes. Animation: How Enzymes Work

43. Figure 5.9-1 Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate.

44. Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate. Substrate (sucrose) Substrate binds to the enzyme. Figure 5.9-2

45. Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate. Substrate (sucrose) Substrate binds to the enzyme. The enzyme catalyzes the chemical reaction. H2OH2O Figure 5.9-3

46. Active site Enzyme (sucrase) Sucrase can accept a molecule of its substrate. Substrate (sucrose) Substrate binds to the enzyme. The enzyme catalyzes the chemical reaction. H2OH2O Fructose Glucose The products are released. Figure 5.9-4

47. © 2010 Pearson Education, Inc. Enzyme Inhibitors Enzyme inhibitors can prevent metabolic reactions by binding to the active site. Blast Animation: Enzyme Regulation: Competitive Inhibition

48. (a) Enzyme and substrate binding normally (b) Enzyme inhibition by a substrate imposter (c) Enzyme inhibition by a molecule that causes the active site to change shape Substrate Active site Inhibitor Enzyme Figure 5.10

49. (a) Enzyme and substrate binding normally Substrate Enzyme Active site Figure 5.10a

50. Figure 5.10b (b) Enzyme inhibition by a substrate imposter Substrate Active site Inhibitor Enzyme

51. (c) Enzyme inhibition by a molecule that causes the active site to change shape Substrate Active site Inhibitor Enzyme Figure 5.10c

52. © 2010 Pearson Education, Inc. Other enzyme inhibitors –Bind at a remote site –Change the enzyme’s shape –Prevent the enzyme from binding to its substrate

53. © 2010 Pearson Education, Inc. Some products of a reaction may inhibit the enzyme required for its production. –This is called feedback regulation. –It prevents the cell from wasting resources. Many antibiotics work by inhibiting enzymes of disease-causing bacteria.

54. © 2010 Pearson Education, Inc. MEMBRANE FUNCTION Working cells must control the flow of materials to and from the environment. Membrane proteins perform many functions. Transport proteins –Are located in membranes –Regulate the passage of materials into and out of the cell Animation: Membrane Selectivity

55. Cell signaling Attachment to the cytoskeleton and extracellular matrix Enzymatic activity Cytoskeleton Cytoplasm Transport Fibers of extracellular matrix Intercellular joining Cell-cell recognition Figure 5.11

56. © 2010 Pearson Education, Inc. Passive Transport: Diffusion across Membranes Molecules contain heat energy that causes them to vibrate and wander randomly. Diffusion is the tendency for molecules of any substance to spread out into the available space.

57. © 2010 Pearson Education, Inc. Animation: Diffusion Blast Animation: Diffusion Passive transport is the diffusion of a substance across a membrane without the input of energy. Diffusion is an example of passive transport. Substances diffuse down their concentration gradient, a region in which the substance’s density changes. Blast Animation: Passive Diffusion Across a Membrane

58. Molecules of dyeMembrane (a) Passive transport of one type of molecule (b) Passive transport of two types of molecules Net diffusion Equilibrium Net diffusion Equilibrium Net diffusion Equilibrium Figure 5.12

59. Molecules of dyeMembrane (a) Passive transport of one type of molecule Net diffusion Equilibrium Figure 5.12a

60. (b) Passive transport of two types of molecules Net diffusion Equilibrium Net diffusion Equilibrium Figure 5.12b

61. © 2010 Pearson Education, Inc. Some substances do not cross membranes spontaneously. –These substances can be transported via facilitated diffusion. –Specific transport proteins act as selective corridors. –No energy input is needed.

62. © 2010 Pearson Education, Inc. Osmosis and Water Balance The diffusion of water across a selectively permeable membrane is osmosis. Animation: Osmosis

63. Hypotonic solutionHypertonic solution Sugar molecule Selectively permeable membrane Osmosis Figure 5.13-1

64. Hypotonic solutionHypertonic solution Sugar molecule Selectively permeable membrane Osmosis Isotonic solutions Osmosis Figure 5.13-2

65. © 2010 Pearson Education, Inc. A hypertonic solution has a higher concentration of solute. A hypotonic solution has a lower concentration of solute. An isotonic solution has an equal concentration of solute.

66. © 2010 Pearson Education, Inc. Osmoregulation is the control of water balance within a cell or organism. Most animal cells require an isotonic environment. Water Balance in Animal Cells

67. © 2010 Pearson Education, Inc. Plant have rigid cell walls. Plant cells require a hypotonic environment, which keeps these walled cells turgid. Water Balance in Plant Cells Video: Plasmolysis

68. Animal cell Plant cell Normal Flaccid (wilts) Lysing Turgid Shriveled Plasma membrane H2OH2O H2OH2O H2OH2OH2OH2O H2OH2O H2OH2O H2OH2O H2OH2O (a) Isotonic solution (b) Hypotonic solution (c) Hypertonic solution Figure 5.14

69. Animal cell Plant cell Normal Flaccid (wilts) H2OH2O H2OH2O H2OH2O H2OH2O (a) Isotonic solution Figure 5.14a

70. Lysing Turgid H2OH2O H2OH2O (b) Hypotonic solution Figure 5.14b

71. Shriveled Plasma membrane H2OH2O H2OH2O (c) Hypertonic solution Figure 5.14c

72. © 2010 Pearson Education, Inc. As a plant cell loses water, –It shrivels. –Its plasma membrane may pull away from the cell wall in the process of plasmolysis, which usually kills the cell. Video: Turgid Elodea

73. Figure 5.15

74. Active Transport: The Pumping of Molecules Across Membranes Active transport requires energy to move molecules across a membrane. © 2010 Pearson Education, Inc. Animation: Active Transport Blast Animation: Active Transport: Sodium-Potassium Pump

75. Lower solute concentration Higher solute concentration ATP Solute Figure 5.16-1

76. Lower solute concentration Higher solute concentration ATP Solute Figure 5.16-2

77. Exocytosis and Endocytosis: Traffic of Large Molecules Exocytosis is the secretion of large molecules within vesicles. © 2010 Pearson Education, Inc. Animation: Exocytosis Animation: Exocytosis and Endocytosis Introduction Blast Animation: Endocytosis and Exocytosis

78. Outside of cell Cytoplasm Plasma membrane Figure 5.17

79. © 2010 Pearson Education, Inc. Endocytosis takes material into a cell within vesicles that bud inward from the plasma membrane. Animation: Receptor-Mediated Endocytosis Animation: Pinocytosis Animation: Phagocytosis

80. Figure 5.18

81. © 2010 Pearson Education, Inc. There are three types of endocytosis: –Phagocytosis (“cellular eating”); a cell engulfs a particle and packages it within a food vacuole –Pinocytosis (“cellular drinking”); a cell “gulps” droplets of fluid by forming tiny vesicles –Receptor-mediated endocytosis; a cell takes in very specific molecules

82. © 2010 Pearson Education, Inc. The Role of Membranes in Cell Signaling The plasma membrane helps convey signals between –Cells –Cells and their environment

83. © 2010 Pearson Education, Inc. Receptors on a cell surface trigger signal transduction pathways that –Relay the signal –Convert it to chemical forms that can function within the cell Animation: Signal Transduction Pathways Animation: Overview of Cell Signaling

84. Outside of cellCytoplasm ReceptionTransductionResponse Receptor protein Epinephrine (adrenaline) from adrenal glands Plasma membrane Proteins of signal transduction pathway Hydrolysis of glycogen releases glucose for energy Figure 5.19

85. Outside of cellCytoplasm Reception TransductionResponse Receptor protein Epinephrine (adrenaline) from adrenal glands Plasma membrane Proteins of signal transduction pathway Hydrolysis of glycogen releases glucose for energy Figure 5.19a

86. Evolution Connection: The Origin of Membranes Phospholipids –Are key ingredients of membranes –Were probably among the first organic compounds that formed before life emerged –Self-assemble into simple membranes © 2010 Pearson Education, Inc.

87. Figure 5.20

88. Energy for cellular work Adenosine diphosphate Energy from organic fuel Phosphate ATP cycle ATPADP PPPPPP Adenosine triphosphate Figure 5.UN01

89. Reactant Products Enzyme added Activation energy Figure 5.UN02

90. Passive Transport (requires no energy) Active Transport (requires energy) DiffusionFacilitated diffusionOsmosis Higher solute concentration Lower solute concentration Higher water concentration (lower solute concentration) Lower water concentration (higher solute concentration) Solute Higher solute concentration Lower solute concentration ATP Solute Water Solute MEMBRANE TRANSPORT Figure 5.UN03

91. ExocytosisEndocytosis Figure 5.UN04