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  1. 1. Photosynthesis Energy & Life copyright cmassengale
  2. 2. Overview of Photosynthesis copyright cmassengale
  3. 3. Autotrophs <ul><ul><li>Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. </li></ul></ul>copyright cmassengale
  4. 4. Autotrophs <ul><li>Autotrophs include organisms that make their own food </li></ul><ul><li>Autotrophs can use the sun’s energy directly </li></ul>Euglena copyright cmassengale
  5. 5. Heterotrophs <ul><li>Heterotrophs are organisms that can NOT make their own food </li></ul><ul><li>Heterotrophs can NOT directly use the sun’s energy </li></ul>copyright cmassengale
  6. 6. Energy <ul><li>Energy Takes Many Forms such as light, heat, electrical, chemical, mechanical </li></ul><ul><li>Energy can be changed from one form to another </li></ul><ul><li>Energy can be stored in chemical bonds & then released later </li></ul>Candles release energy as HEAT & LIGHT copyright cmassengale
  7. 7. ATP – Cellular Energy <ul><li>Adenosine Triphosphate </li></ul><ul><li>Contains two, high-energy phosphate bonds </li></ul><ul><li>Also contains the nitrogen base adenine & a ribose sugar </li></ul>copyright cmassengale
  8. 8. ADP <ul><ul><li>Adenosine Diphosphate </li></ul></ul><ul><ul><li>ATP releases energy , a free phosphate, & ADP when cells take energy from ATP </li></ul></ul>One phosphate bond has been removed copyright cmassengale
  9. 9. Sugar in ADP & ATP <ul><li>Called ribose </li></ul><ul><li>Pentose sugar </li></ul><ul><li>Also found on RNA </li></ul>copyright cmassengale
  10. 10. Importance of ATP <ul><li>Principal Compound Used To Store Energy In Living Organisms </li></ul>copyright cmassengale
  11. 11. Releasing Energy From ATP <ul><li>ATP is constantly being used and remade by cells </li></ul><ul><li>ATP provides all of the energy for cell activities </li></ul><ul><li>The high energy phosphate bonds can be BROKEN to release energy </li></ul><ul><li>The process of releasing ATP’s energy & reforming the molecule is called phosphorylation </li></ul>copyright cmassengale
  12. 12. Releasing Energy From ATP <ul><li>Adding A Phosphate Group To ADP stores Energy in ATP </li></ul><ul><li>Removing A Phosphate Group From ATP Releases Energy & forms ADP </li></ul>Loose Gain copyright cmassengale
  13. 13. Cells Using Biochemical Energy <ul><li>Cells Use ATP For: </li></ul><ul><li>Active transport </li></ul><ul><li>Movement </li></ul><ul><li>Photosynthesis </li></ul><ul><li>Protein Synthesis </li></ul><ul><li>Cellular respiration </li></ul><ul><li>All other cellular reactions </li></ul>copyright cmassengale
  14. 14. More on ATP <ul><li>Cells Have Enough ATP To Last For A Few Seconds </li></ul><ul><li>ATP must constantly be made </li></ul><ul><li>ATP Transfers Energy Very Well </li></ul><ul><li>ATP Is NOT Good At Energy Storage </li></ul>copyright cmassengale
  15. 15. Glucose <ul><li>Glucose is a monosaccharide </li></ul><ul><li>C 6 H 12 O 6 </li></ul><ul><li>One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP </li></ul>copyright cmassengale
  16. 16. History of Photosynthesis & Plant Pigments copyright cmassengale
  17. 17. Photosynthesis <ul><li>Involves the Use Of light Energy to convert Water (H 2 0) and Carbon Dioxide (CO 2 ) into Oxygen (O 2 ) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches </li></ul>copyright cmassengale
  18. 18. Investigating Photosynthesis <ul><ul><li>Many Scientists Have Contributed To Understanding Photosynthesis </li></ul></ul><ul><ul><li>Early Research Focused On The Overall Process </li></ul></ul><ul><ul><li>Later Researchers Investigated The Detailed Chemical Pathways </li></ul></ul>copyright cmassengale
  19. 19. Early Questions on Plants <ul><li>Several Centuries Ago, The Question Was: Does the increase in mass of a plant come from the air? The soil? The Water? </li></ul>copyright cmassengale
  20. 20. Van Helmont’s Experiment 1643 <ul><li>Planted a seed into A pre-measured amount of soil and watered for 5 years </li></ul><ul><li>Weighed Plant & Soil. Plant Was 75 kg, Soil The Same. </li></ul><ul><li>Concluded Mass Came From Water </li></ul>copyright cmassengale
  21. 21. Priestley’s Experiment 1771 <ul><li>Burned Candle In Bell Jar Until It Went Out. </li></ul><ul><li>Placed Sprig Of Mint In Bell Jar For A Few Days. </li></ul><ul><li>Candle Could Be Relit And Burn. </li></ul><ul><li>Concluded Plants Released Substance (O 2 ) Necessary For burning. </li></ul>copyright cmassengale
  22. 22. Ingenhousz’s Experiment 1779 Repeated Priestly experiment with & without sunlight copyright cmassengale
  23. 23. Results of Ingenhousz’s Experiment <ul><li>Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight . </li></ul><ul><li>Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen </li></ul>copyright cmassengale
  24. 24. Julius Robert Mayer 1845 <ul><li>Proposed That Plants can Convert Light Energy Into Chemical Energy </li></ul>copyright cmassengale
  25. 25. Samuel Ruben & Martin Kamen 1941 <ul><li>Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water </li></ul>KAMEN RUBIN copyright cmassengale
  26. 26. Melvin Calvin 1948 <ul><li>First to trace the path that carbon (CO 2 ) takes in forming Glucose </li></ul><ul><li>Does NOT require sunlight </li></ul><ul><li>Called the Calvin Cycle or Light Independent Reaction </li></ul><ul><li>Also known as the Dark Reaction </li></ul>copyright cmassengale
  27. 27. Rudolph Marcus 1992 <ul><li>Studied the Light Independent Reactions </li></ul><ul><li>First to describe the Electron transport Chain </li></ul>copyright cmassengale
  28. 28. The Photosynthesis Equation copyright cmassengale
  29. 29. Pigments <ul><ul><li>In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments </li></ul></ul><ul><ul><li>Chlorophyll is the primary light-absorbing pigment in autotrophs </li></ul></ul><ul><ul><li>Chlorophyll is found inside chloroplasts </li></ul></ul>copyright cmassengale
  30. 30. Light and Pigments <ul><li>Energy From The Sun Enters Earth’s Biosphere As Photons </li></ul><ul><li>Photon = Light Energy Unit </li></ul><ul><li>Light Contains A Mixture Of Wavelengths </li></ul><ul><li>Different Wavelengths Have Different Colors </li></ul>copyright cmassengale
  31. 31. Light & Pigments <ul><li>Different pigments absorb different wavelengths of light </li></ul><ul><li>Photons of light “excite” electrons in the plant’s pigments </li></ul><ul><li>Excited electrons carry the absorbed energy </li></ul><ul><li>Excited electrons move to HIGHER energy levels </li></ul>copyright cmassengale
  32. 32. Chlorophyll <ul><li>There are 2 main types of chlorophyll molecules: </li></ul><ul><li>Chlorophyll a </li></ul><ul><li>Chlorophyll b </li></ul><ul><li>A third type, chlorophyll c , is found in dinoflagellates </li></ul>Magnesium atom at the center of chlorophyll copyright cmassengale
  33. 33. Chlorophyll a and b copyright cmassengale
  34. 34. Chlorophyll a <ul><li>Found in all plants, algae, & cyanobacteria </li></ul><ul><li>Makes photosynthesis possible </li></ul><ul><li>Participates directly in the Light Reactions </li></ul><ul><li>Can accept energy from chlorophyll b </li></ul>copyright cmassengale
  35. 35. Chlorophyll b <ul><li>Chlorophyll b is an accessory pigment </li></ul><ul><li>Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a </li></ul><ul><li>Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN </li></ul>copyright cmassengale
  36. 36. The Biochemical Reactions copyright cmassengale
  37. 37. It Begins with Sunlight! copyright cmassengale
  38. 38. Photoautotrophs Absorb Light Energy copyright cmassengale
  39. 39. Inside A Chloroplast copyright cmassengale
  40. 40. Structure of the Chloroplast <ul><li>Double membrane organelle </li></ul><ul><li>Outer membrane smooth </li></ul><ul><li>Inner membrane forms stacks of connected sacs called thylakoids </li></ul><ul><li>Thylakoid stack is called the granun (grana-plural) </li></ul><ul><li>Gel-like material around grana called stroma </li></ul>copyright cmassengale
  41. 41. Function of the Stroma <ul><li>Light Independent reactions occur here </li></ul><ul><li>ATP used to make carbohydrates like glucose </li></ul><ul><li>Location of the Calvin Cycle </li></ul>copyright cmassengale
  42. 42. copyright cmassengale
  43. 43. Thylakoid membranes <ul><li>Light Dependent reactions occur here </li></ul><ul><li>Photosystems are made up of clusters of chlorophyll molecules </li></ul><ul><li>Photosystems are embedded in the thylakoid membranes </li></ul><ul><li>The two photosystems are: </li></ul><ul><li>Photosytem I </li></ul><ul><li>Photosystem II </li></ul>copyright cmassengale
  44. 44. Photosynthesis Overview copyright cmassengale
  45. 45. Energy Carriers <ul><li>Nicotinamide Adenine Dinucleotide Phosphate (NADP + ) </li></ul><ul><li>NADP + = Reduced Form </li></ul><ul><li>Picks Up 2 high-energy electrons and H + from the Light Reaction to form NADPH </li></ul><ul><li>NADPH carries energy to be passed on to another molecule </li></ul>copyright cmassengale
  46. 46. NADPH copyright cmassengale
  47. 47. <ul><li>Occurs across the thylakoid membranes </li></ul><ul><li>Uses light energy </li></ul><ul><li>Produce Oxygen from water </li></ul><ul><li>Convert ADP to ATP </li></ul><ul><li>Also convert NADP + into the energy carrier NADPH </li></ul>Light Dependent Reactions copyright cmassengale
  48. 48. Light Dependent Reaction copyright cmassengale
  49. 49. Light Dependent Reaction copyright cmassengale
  50. 50. Photosystem I <ul><ul><li>Discovered First </li></ul></ul><ul><ul><li>Active in the final stage of the Light Dependent Reaction </li></ul></ul><ul><ul><li>Made of 300 molecules of Chlorophyll </li></ul></ul><ul><ul><li>Almost completely chlorophyll a </li></ul></ul>copyright cmassengale
  51. 51. Photosystem II <ul><ul><li>Discovered Second </li></ul></ul><ul><ul><li>Active in the beginning stage Of the Light Dependent Reaction </li></ul></ul><ul><ul><li>Contains about equal amounts of chlorophyll a and chlorophyll b </li></ul></ul>copyright cmassengale
  52. 52. Photosynthesis Begins <ul><ul><li>Photosystem II absorbs light energy </li></ul></ul><ul><ul><li>Electrons are energized and passed to the Electron Transport Chain </li></ul></ul><ul><ul><li>Lost electrons are replaced from the splitting of water into 2H +, free electrons, and Oxygen </li></ul></ul><ul><ul><li>2H + pumped across thylakoid membrane </li></ul></ul>copyright cmassengale
  53. 53. Photosystem I <ul><li>High-energy electrons are moved to Photosystem I through the Electron Transport Chain </li></ul><ul><li>Energy is used to transport H + from stroma to inner thylakoid membrane </li></ul><ul><li>NADP+ converted to NADPH when it picks up 2 electrons & H+ </li></ul>copyright cmassengale
  54. 54. Phosphorylation <ul><li>Enzyme in thylakoid membrane called ATP Synthase </li></ul><ul><li>As H+ ions passed through thylakoid membrane, enzyme binds them to ADP </li></ul><ul><li>Forms ATP for cellular </li></ul>copyright cmassengale
  55. 55. copyright cmassengale
  56. 56. Light Reaction Summary <ul><li>Reactants: </li></ul><ul><li>H 2 O </li></ul><ul><li>Light Energy </li></ul><ul><li>Energy Products: </li></ul><ul><li>ATP </li></ul><ul><li>NADPH </li></ul>copyright cmassengale
  57. 57. Light Independent Reaction <ul><li>ATP & NADPH from light reactions used as energy </li></ul><ul><li>Atmospheric C0 2 is used to make sugars like glucose and fructose </li></ul><ul><li>Six-carbon Sugars made during the Calvin Cycle </li></ul><ul><li>Occurs in the stroma </li></ul>copyright cmassengale
  58. 58. The Calvin Cycle copyright cmassengale
  59. 59. The Calvin Cycle <ul><li>Two turns of the Calvin Cycle are required to make one molecule of glucose </li></ul><ul><li>3-CO 2 molecules enter the cycle to form several intermediate compounds (PGA) </li></ul><ul><li>A 3-carbon molecule called Ribulose Biphosphate (RuBP) is used to regenerate the Calvin cycle </li></ul>copyright cmassengale
  60. 60. copyright cmassengale
  61. 61. Factors Affecting the Rate of Photosynthesis <ul><li>Amount of available water </li></ul><ul><li>Temperature </li></ul><ul><li>Amount of available light energy </li></ul>copyright cmassengale
  62. 62. copyright cmassengale