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Photosynthesis

Photosynthesis. Energy & Life. Overview of Photosynthesis. Autotrophs. Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food. Autotrophs. Autotrophs include organisms that make their own food

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Photosynthesis

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  1. Photosynthesis Energy & Life

  2. Overview of Photosynthesis

  3. Autotrophs Plants and some other types of organisms that contain chlorophyll are able to use light energy from the sun to produce food.

  4. Autotrophs • Autotrophs include organismsthat make their own food • Autotrophs can use the sun’s energy directly Euglena

  5. Heterotrophs • Heterotrophs are organisms that can NOT make their own food • Heterotrophs can NOT directly use the sun’s energy

  6. Energy • Energy Takes Many Forms such as light, heat, electrical, chemical, mechanical • Energy can be changed from one form to another • Energy can be stored in chemical bonds & then released later Candles release energy as HEAT & LIGHT

  7. ATP – Cellular Energy • Adenosine Triphosphate • Contains two, high-energy phosphate bonds • Also contains the nitrogen base adenine & a ribose sugar

  8. ADP • Adenosine Diphosphate • ATP releases energy, a free phosphate, & ADP when cells take energy from ATP One phosphate bond has been removed

  9. Sugar in ADP & ATP • Called ribose • Pentose sugar • Also found on RNA

  10. Importance of ATP Principal Compound Used To Store Energy In Living Organisms

  11. Releasing Energy From ATP • ATP is constantly being used and remade by cells • ATP provides all of the energy for cell activities • The high energy phosphate bonds can be BROKEN to release energy • The process of releasing ATP’s energy & reforming the molecule is called phosphorylation

  12. Releasing Energy From ATP • Adding A Phosphate Group To ADP stores Energy in ATP • Removing A Phosphate Group From ATP Releases Energy & forms ADP Loose Gain

  13. Cells Using Biochemical Energy Cells Use ATP For: • Active transport • Movement • Photosynthesis • Protein Synthesis • Cellular respiration • All other cellular reactions

  14. More on ATP • Cells Have Enough ATP To Last For A Few Seconds • ATP must constantly be made • ATP Transfers Energy Very Well • ATP Is NOT Good At Energy Storage

  15. Glucose • Glucose is a monosaccharide • C6H12O6 • One Molecule of glucose Stores 90 Times More Chemical Energy Than One Molecule of ATP

  16. History of Photosynthesis & Plant Pigments

  17. Photosynthesis • Involves the Use Of light Energy to convert Water (H20) and Carbon Dioxide (CO2) into Oxygen (O2) and High Energy Carbohydrates (sugars, e.g. Glucose) & Starches

  18. The Photosynthesis Equation

  19. Investigating Photosynthesis • Many Scientists Have Contributed To Understanding Photosynthesis • Early Research Focused On The Overall Process • Later Researchers Investigated The Detailed Chemical Pathways

  20. Early Questions on Plants Several Centuries Ago, The Question Was:Does the increase in mass of a plant come from the air? The soil? The Water?

  21. Van Helmont’s Experiment 1643 • Planted a seed into A pre-measured amount of soil and watered for 5 years • Weighed Plant & Soil. Plant Was 75 kg, Soil The Same. • Concluded Mass Came From Water

  22. Priestley’s Experiment 1771 • Burned Candle In Bell Jar Until It Went Out. • Placed Sprig Of Mint In Bell Jar For A Few Days. • Candle Could Be Relit And Burn. • Concluded Plants Released Substance (O2) Necessary For burning.

  23. Ingenhousz’s Experiment 1779 Repeated Priestly experiment with & without sunlight

  24. Results of Ingenhousz’s Experiment • Showed That Priestley’s Results Only Occurred In The Presence Of Sunlight. • Light Was Necessary For Plants To Produce The “Burning Gas” or oxygen

  25. Julius Robert Mayer 1845 Proposed That Plants can Convert Light Energy Into Chemical Energy

  26. Samuel Ruben & Martin Kamen1941 Used Isotopes To Determine That The Oxygen Liberated In Photosynthesis Comes From Water RUBIN KAMEN

  27. Melvin Calvin 1948 • First to trace the path that carbon (CO2) takes in forming Glucose • Does NOT require sunlight • Called the Calvin Cycle or Light Independent Reaction • Also knownas the Dark Reaction

  28. Rudolph Marcus 1992 • Studied the Light Independent Reactions • First to describe the Electron transport Chain

  29. The Photosynthesis Equation

  30. Pigments • In addition to water, carbon dioxide, and light energy, photosynthesis requires Pigments • Chlorophyll is the primary light-absorbing pigment in autotrophs • Chlorophyll is found inside chloroplasts in the thylakoids

  31. Light and Pigments • Energy From The Sun Enters Earth’s Biosphere As Photons • Photon = Light Energy Unit • Light Contains A Mixture Of Wavelengths • Different Wavelengths Have Different Colors

  32. Light & Pigments • Different pigments absorb different wavelengths of light • Photons of light “excite” electrons in the plant’s pigments • Excited electrons carry the absorbed energy • Excited electrons move to HIGHER energy levels

  33. Pigments There are 4 main types of pigment molecules: Chlorophyll a Chlorophyll b Xanthophyll Carotenes

  34. Chlorophyll a and b

  35. Chlorophyll a • Found in all plants, algae, & cyanobacteria • Makes photosynthesis possible • Participates directly in the Light Reactions • Can accept energy from chlorophyll b

  36. Chlorophyll b • Chlorophyll b is an accessory pigment • Chlorophyll b acts indirectly in photosynthesis by transferring the light it absorbs to chlorophyll a • Like chlorophyll a, it absorbs red & blue light and REFLECTS GREEN

  37. The Biochemical Reactions

  38. It Begins with Sunlight!

  39. Flow of Energy

  40. Photoautotrophs Absorb Light Energy

  41. Objectives • Summarize how energy is captured from sunlight in the first stage of photosynthesis. • Analyze the function of electron transport chains in the second stage of photosynthesis. • Relate the Calvin cycle to carbon dioxide fixation in the third stage of photosynthesis. • Identify three environmental factors that affect the rate of photosynthesis.

  42. Pigment Chlorophyll Carotenoid Thylakoid Electron Transport Chain NADPH Carbon Dioxide Fixation Calvin Cycle Key Terms

  43. Chloroplast Mesophyll Cell Stoma Where does Photosynthesis occur? • Plants/Autotrophs – produce their own food (glucose) • Process called photosynthesis • Mainly occurs in the leaves: a. stoma - pores b. mesophyll cells-chloroplasts found in this area

  44. Structure of the Chloroplast • Double membrane organelle • Outer membrane smooth • Inner membrane forms stacks of connected sacs called thylakoids • Thylakoid stack is called the granun (grana-plural) • Gel-like material around grana called stroma

  45. Inside A Chloroplast

  46. The 2 Stages of Photosynthesis • Stage 1-Light Reaction • Energy is captured from sunlight by chlorophyll and other pigments present. • Light energy is converted to chemical energy as water is split, which is temporarily stored in ATP & the energy carrier molecule NADPH and O2 gas is given off • Stage 2 -Light Independent Reaction/Dark Reaction/Calvin Cycle • The chemical energy stored in ATP & NADPH powers the formation of organic compounds from the combination of RuBP and the CO2 to eventually makes Glucose.

  47. Stages of Photosynthesis RuBP Celluslose

  48. The Photosynthesis Equation Light 6CO2 + 6H20 C6H12O6 + 6O2 Carbon Dioxide Water Sugars Oxygen (High Energy)

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