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Chapter Eight- Photosynthesis

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Chapter Eight Lecture on photosynthesis for Lab Bio

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Chapter Eight- Photosynthesis

  1. 1. 8-1 Energy and Life Copyright Pearson Prentice Hall
  2. 2. Living things need energy to survive. This energy comes from food. The energy in most food comes from the sun. Copyright Pearson Prentice Hall
  3. 3. Plants are able to use light energy from the sun to produce food.
  4. 4. autotrophs –Organisms that make their own food, such as plants. heterotrophs must get energy from the foods they consume. Ex. Animals I can make my own food!! Copyright Pearson Prentice Hall I will eat you!!
  5. 5. Chemical Energy and ATP Energy comes in many forms including light, heat, and electricity. Energy can be stored in chemical compounds, too. Copyright Pearson Prentice Hall
  6. 6. Chemical Energy and ATP An important chemical compound that cells use to store and release energy is adenosine triphosphate, abbreviated ATP. Adenosine triphosphate or ATP is used by all types of cells as their basic energy source. ATP Movie
  7. 7. ATP consists of: •adenine •ribose (a 5-carbon sugar) •3 phosphate groups Adenine ATP Ribose 3 Phosphate groups
  8. 8. Chemical Energy and ATP The three phosphate groups are the key to ATP's ability to store and release energy.
  9. 9. Storing Energy ADP has two phosphate groups instead of three. A cell can store small amounts of energy by adding a phosphate group to ADP. ADP ATP Energy Energy Copyright Pearson Prentice Hall Partially charged battery Fully charged battery + Adenosine Diphosphate (ADP) + Phosphate Adenosine Triphosphate (ATP)
  10. 10. Chemical Energy and ATP Releasing Energy Energy stored in ATP is released by breaking off the third phosphate. Copyright Pearson Prentice Hall P ADP 2 Phosphate groups
  11. 11. Chemical Energy and ATP The energy from ATP is needed for many cellular activities, including active transport across cell membranes, protein synthesis and muscle contraction. ATP’s characteristics make it exceptionally useful as the basic energy source of all cells. Copyright Pearson Prentice Hall
  12. 12. Using Biochemical Energy Using Biochemical Energy Most cells have only a small amount of ATP, because it is not a good way to store large amounts of energy. Cells can regenerate ATP from ADP as needed by using the energy in foods like glucose. Copyright Pearson Prentice Hall
  13. 13. Copyright Pearson Prentice Hall 8-1 Organisms that make their own food are called a. autotrophs. b. heterotrophs. c. decomposers. d. consumers.
  14. 14. Copyright Pearson Prentice Hall 8-1 Most autotrophs obtain their energy from a. chemicals in the environment. b. sunlight. c. carbon dioxide in the air. d. other producers.
  15. 15. Copyright Pearson Prentice Hall 8-1 How is energy released from ATP? a. A phosphate is added. b. An adenine is added. c. A phosphate is removed. d. A ribose is removed.
  16. 16. Copyright Pearson Prentice Hall 8-1 How is it possible for most cells to function with only a small amount of ATP? a. Cells do not require ATP for energy. b. ATP can be quickly regenerated from ADP and P. c. Cells use very small amounts of energy. d. ATP stores large amounts of energy.
  17. 17. Copyright Pearson Prentice Hall 8-1 Compared to the energy stored in a molecule of glucose, ATP stores a. much more energy. b. much less energy. c. about the same amount of energy. d. more energy sometimes and less at others.
  18. 18. 8-2 Photosynthesis: An Copyright Pearson Prentice Hall Overview
  19. 19. Copyright Pearson Prentice Hall Photosy nthesis: An Overvie w The key cellular process identified with energy production is photosynthesis. Photosynthesis is the process in which green plants use the energy of sunlight to convert water and carbon dioxide into sugar and oxygen.
  20. 20. Investigating Photosynthesis Research into photosynthesis began centuries ago. Van Helmont’s Experiment a. In the 1600s, Jan van Helmont wanted to find out if plants grew by taking material out of the soil. b. He determined the mass of a pot of dry soil and a small seedling, planted the seedling in the pot, and watered it regularly. c. After five years, the seedling was a small tree and had gained 75 kg, but the soil’s mass was almost unchanged.
  21. 21. Copyright Pearson Prentice Hall igatin g Photo synth a.Van Helmont concluded that the gain in a plants’ mass comes from water because water was the only thing he had added. b. His experiment accounts for the “hydrate,” or water, portion of the carbohydrate produced by photosynthesis.
  22. 22. Copyright Pearson Prentice Hall igatin g Photo synth a. Although van Helmont did not realize it, carbon dioxide in the air also made a major contribution to the mass of his tree. b. In photosynthesis, the carbon in carbon dioxide is used to make sugars and other carbohydrates. c. Van Helmont had only part of the story, but he had made a major contribution to science.
  23. 23. Joseph Priestley discovered oxygen and that plants release it. More than 100 years after van Helmont’s experiment-- a. Priestley took a candle, placed a glass jar over it, and watched as the flame gradually died out. b. He reasoned that the flame needed something in the air to keep burning and when it was used up, the flame went out. That substance was oxygen. Copyright Pearson Prentice Hall
  24. 24. a. Priestley then placed a live sprig of mint under the jar and allowed a few days to pass. b. He found that the candle could be relighted and would remain lighted for a while. c. The mint plant had produced the substance required for burning. In other words, it had released oxygen. Copyright Pearson Prentice Hall
  25. 25. Jan Ingenhousz a.Later, Jan Ingenhousz showed that the effect observed by Priestley occurred only when the plant was exposed to light. b. The results of both Priestley’s and Ingenhousz’s experiments showed that light is necessary for plants to produce oxygen. Copyright Pearson Prentice Hall
  26. 26. Copyright Pearson Prentice Hall igatin g Photo synth The experiments performed by van Helmont, Priestley, and Ingenhousz led to work by other scientists who finally discovered that, in the presence of light, plants transform carbon dioxide and water into carbohydrates, and they also release oxygen.
  27. 27. The equation for photosynthesis is 6CO2 + 6H2O Light C6H12O6 + 6O2 carbon water sugars oxygen dioxide Photosynthesis uses the energy of sunlight to convert water and carbon dioxide into high-energy sugars and oxygen. Photosynthesis activity
  28. 28. Light energy Copyright Pearson Prentice Hall O2 CO2 + H20 ADP NADP+ Sugar Light- Dependent Reactions (thylakoids) H2O ATP NADPH Calvin Cycle (stroma)
  29. 29. Copyright Pearson Prentice Hall Light and Pigme nts In addition to water and carbon dioxide, photosynthesis requires light and chlorophyll.
  30. 30. Plants gather the sun's energy with light-absorbing molecules called pigments. The main light-absorbing pigment in plants is chlorophyll. There are two main types of chlorophyll: Copyright Pearson Prentice Hall chlorophyll a chlorophyll b
  31. 31. Chlorophyll absorbs light well in the blue-violet and red regions of the visible spectrum. Wavelength (nm) Copyright Pearson Prentice Hall 100 80 60 40 20 0 400 450 500 550 600 650 700 750 Wavelength (nm) Estimated Absorption (%)
  32. 32. Chlorophyll does not absorb light well in the green region of the spectrum. Green light is reflected by leaves, which is why plants look green. Wavelength (nm) Copyright Pearson Prentice Hall 100 80 60 40 20 0 400 450 500 550 600 650 700 750 Wavelength (nm) Estimated Absorption (%)
  33. 33. Light is a form of energy, so any compound that absorbs light also absorbs energy from that light. When chlorophyll absorbs light, much of the energy is transferred directly to electrons in the chlorophyll molecule, raising the energy levels of these electrons. These high-energy electrons are what make photosynthesis work. Copyright Pearson Prentice Hall
  34. 34. Copyright Pearson Prentice Hall 8-2 In van Helmont's experiment, most of the added mass of the tree came from a. soil and carbon dioxide. b. water and carbon dioxide. c. oxygen and carbon dioxide. d. soil and oxygen.
  35. 35. Copyright Pearson Prentice Hall 8-2 Plants use the sugars produced in photosynthesis to make a. oxygen. b. starches. c. carbon dioxide. d. protein.
  36. 36. Copyright Pearson Prentice Hall 8-2 The raw materials required for plants to carry out photosynthesis are a. carbon dioxide and oxygen. b. oxygen and sugars. c. carbon dioxide and water. d. oxygen and water.
  37. 37. Copyright Pearson Prentice Hall 8-2 The principal pigment in plants is a. chloroplast. b. chlorophyll. c. carotene. d. carbohydrate.
  38. 38. Copyright Pearson Prentice Hall 8-2 The colors of light that are absorbed by chlorophylls are a. green and yellow. b. green, blue, and violet. c. blue, violet, and red. d. red and yellow.
  39. 39. 8-3 The Reactions of Photosynthesis Copyright Pearson Prentice Hall
  40. 40. Inside a Chloroplast In plants, photosynthesis takes place inside chloroplasts. Plant Plant cells Copyright Pearson Prentice Hall Chloroplast Chloroplast movie
  41. 41. Chloroplasts contain thylakoids— saclike photosynthetic membranes. Copyright Pearson Prentice Hall Chloroplast Single thylakoid
  42. 42. Copyright Pearson Prentice Hall Inside a Chlor opTlahstylakoids are arranged in stacks known as grana. A singular stack is called a granum. Granum Chloroplast
  43. 43. Proteins in the thylakoid membrane organize chlorophyll and other pigments into clusters called photosystems, which are the light-collecting units of the chloroplast. Copyright Pearson Prentice Hall Chloroplast Photosystems
  44. 44. The long chain of photosynthesis reactions is divided into two parts The light-dependent reactions take place within the thylakoid membranes. The Calvin cycle takes place in the stroma, which is the region outside the thylakoid membranes. Copyright Pearson Prentice Hall
  45. 45. Light Chloroplast H2O O2 Copyright PHOTOSYNTHESIS Pearson Prentice Hall CO2 Sugars NADP+ ADP + P Light-dependent reactions Calvin cycle
  46. 46. Copyright Pearson Prentice Hall Electr on Carrie rs When electrons in chlorophyll absorb sunlight, the electrons gain a great deal of energy. Cells use electron carriers to transport these high-energy electrons from chlorophyll to other molecules.
  47. 47. Copyright Pearson Prentice Hall Electr on Carrie rs One carrier molecule is NADP+. Electron carriers, such as NADP+, transport electrons. NADP+ accepts and holds 2 high-energy electrons along with a hydrogen ion (H +). This converts the NADP+ into NADPH.
  48. 48. Copyright Pearson Prentice Hall Electr on Carrie rs The conversion of NADP+ into NADPH is one way some of the energy of sunlight can be trapped in chemical form. The NADPH carries high-energy electrons to chemical reactions elsewhere in the cell. These high-energy electrons are used to help build a variety of molecules the cell needs, including carbohydrates like glucose.
  49. 49. The light-dependent reactions require light. The light-dependent reactions produce oxygen gas and convert ADP and NADP+ into the energy carriers ATP and NADPH. Copyright Pearson Prentice Hall Light-dependent movie
  50. 50. Copyright Pearson Prentice Hall Depen dent Reacti ons Photosystems I and II carry out the light-dependent reactions and are in the thylakoid membrane.
  51. 51. Depen dent Reacti ons Photosynthesis begins when pigments in Copyright Pearson Prentice Hall Photosystem II photosystem II absorb light, increasing their energy level.
  52. 52. These high-energy electrons are passed on to the electron transport chain. Photosystem II Electron carriers High-energy electron
  53. 53. Enzymes on the thylakoid membrane break water molecules into: Copyright Pearson Prentice Hall Photosystem II 2H2O Electron carriers High-energy electron
  54. 54. hydrogen ions oxygen atoms energized electrons Copyright Pearson Prentice Hall Photosystem II 2H2O + O2 Electron carriers High-energy electron
  55. 55. The energized electrons from water replace the high-energy electrons that chlorophyll lost to the electron transport chain. Copyright Pearson Prentice Hall Photosystem II 2H2O + O2 High-energy electron
  56. 56. As plants remove electrons from water, oxygen is left behind and is released into the air. Copyright Pearson Prentice Hall Photosystem II 2H2O + O2 High-energy electron
  57. 57. The hydrogen ions left behind when water is broken apart are released inside the thylakoid membrane. Copyright Pearson Prentice Hall Photosystem II 2H2O + O2 High-energy electron
  58. 58. Energy from the electrons is used to transport H+ ions from the stroma into the inner thylakoid space. Copyright Pearson Prentice Hall Photosystem II 2H2O + O2
  59. 59. High-energy electrons move through the electron transport chain from photosystem II to photosystem I. Copyright Pearson Prentice Hall Photosystem II 2H2O + O2 Photosystem I
  60. 60. Pigments in photosystem I use energy from light to re-energize the electrons. Copyright Pearson Prentice Hall 2H2O + O2 Photosystem I
  61. 61. NADP+ then picks up these high-energy electrons, along with H+ ions, and becomes NADPH. Copyright Pearson Prentice Hall 2H2O + O2 2 NADP+ 2 2 NADPH
  62. 62. As electrons are passed from chlorophyll to NADP+, more H+ ions are pumped across the membrane. Copyright Pearson Prentice Hall 2H2O + O2 2 NADP+ 2 2 NADPH
  63. 63. Soon, the inside of the membrane fills up with positively charged hydrogen ions, which makes the outside of the membrane negatively charged. Copyright Pearson Prentice Hall 2H2O + O2 2 NADP+ 2 2 NADPH
  64. 64. The difference in charges across the membrane provides the energy to make ATP Copyright Pearson Prentice Hall 2H2O + O2 2 NADP+ 2 2 NADPH
  65. 65. H+ ions cannot cross the membrane directly. Copyright Pearson Prentice Hall 2H2O + O2 ATP synthase 2 NADP+ 2 2 NADPH
  66. 66. The cell membrane contains a protein called ATP synthase that allows H+ ions to pass through it Copyright Pearson Prentice Hall 2H2O + O2 ATP synthase 2 NADP+ 2 2 NADPH
  67. 67. As H+ ions pass through ATP synthase, the protein rotates. Copyright Pearson Prentice Hall 2H2O + O2 ATP synthase 2 NADP+ 2 2 NADPH
  68. 68. As it rotates, ATP synthase binds ADP and a phosphate group together to produce ATP. Copyright Pearson Prentice Hall 2H2O + O2 2 NADP+ 2 ATP synthase ADP 2 NADPH
  69. 69. Because of this system, light-dependent electron transport produces not only high-energy Copyright Pearson Prentice Hall 2H2O electrons but ATP as well. + O2 ATP synthase 2 NADP+ ADP 2 2 NADPH
  70. 70. The light-dependent reactions use water, ADP, and NADP+. The light-dependent reactions produce oxygen, ATP, and NADPH. These compounds provide the energy to build energy-containing sugars from low-energy compounds. Copyright Pearson Prentice Hall
  71. 71. The Calvin Cycle ATP and NADPH formed by the light-dependent reactions contain an abundance of chemical energy, but they are not stable enough to store that energy for more than a few minutes. During the Calvin cycle plants use the energy that ATP and NADPH contain to build high-energy compounds that can be stored for a Copyright Pearson Prentice Hall long time.
  72. 72. The Calvin cycle uses ATP and NADPH from the light-dependent reactions to produce high-energy sugars. Because the Calvin cycle does not require light, these reactions are also called the light-independent reactions. Copyright Pearson Prentice Hall Calvin Cycle Movie
  73. 73. Six carbon dioxide molecules enter the cycle from the atmosphere and combine with six 5-carbon molecules. Copyright Pearson Prentice Hall CO2 Enters the Cycle
  74. 74. The result is twelve 3-carbon molecules, which are then converted into higher-energy forms. Copyright Pearson Prentice Hall
  75. 75. The energy for this conversion comes from ATP and high-energy electrons from NADPH. Copyright Pearson Prentice Hall Energy Input 12 12 ADP 12 NADPH 12 NADP+
  76. 76. Two of twelve 3-carbon molecules are removed from the cycle. Copyright Pearson Prentice Hall Energy Input 12 12 ADP 12 NADPH 12 NADP+
  77. 77. Copyright Pearson Prentice Hall The Calvin Cycle The molecules are used to produce sugars, lipids, amino acids and other compounds. 12 12 ADP 6-Carbon sugar produced Sugars and other compounds 12 NADPH 12 NADP+
  78. 78. The 10 remaining 3-carbon molecules are converted back into six 5-carbon molecules, which are used to begin the next cycle. Copyright Pearson Prentice Hall 6 ADP 5-Carbon Molecules Regenerated 12 12 ADP Sugars and other compounds 6 12 NADPH 12 NADP+
  79. 79. The two sets of photosynthetic reactions work together. The light-dependent reactions trap sunlight energy in chemical form. The light-independent reactions use that chemical energy to produce stable, high-energy sugars from carbon dioxide and water. Copyright Pearson Prentice Hall
  80. 80. Many factors affect the rate of photosynthesis, including: • Water • Temperature • Intensity of light Copyright Pearson Prentice Hall Photosynthesis overview movie
  81. 81. Copyright Pearson Prentice Hall 8-3 In plants, photosynthesis takes place inside the a. thylakoids. b. chloroplasts. c. photosystems. d. chlorophyll.
  82. 82. Copyright Pearson Prentice Hall 8-3 Energy to make ATP in the chloroplast comes most directly from a. hydrogen ions flowing through an enzyme in the thylakoid membrane. b. transfer of a phosphate from ADP. c. electrons moving through the electron transport chain. d. electrons transferred directly from NADPH.
  83. 83. Copyright Pearson Prentice Hall 8-3 NADPH is produced in light-dependent reactions and carries energy in the form of a. ATP. b. high-energy electrons. c. low-energy electrons. d. ADP.
  84. 84. Copyright Pearson Prentice Hall 8-3 What is another name for the Calvin cycle? a. light-dependent reactions b. light-independent reactions c. electron transport chain d. photosynthesis
  85. 85. Copyright Pearson Prentice Hall 8-3 Which of the following factors does NOT directly affect photosynthesis? a. wind b. water supply c. temperature d. light intensity

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