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PHOTOSYNTHESIS

PHOTOSYNTHESIS. Photosynthesis: Life from Light and Air. CAPTURING THE ENERGY IN LIGHT. The process by which organisms obtain energy directly from sunlight is called photosynthesis. CO 2 + H 2 O → C 6 H 12 O 6 + O 2. ENERGY FOR LIFE PROCESSES.

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PHOTOSYNTHESIS

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  1. PHOTOSYNTHESIS

  2. Photosynthesis:LifefromLight andAir

  3. CAPTURING THE ENERGYIN LIGHT • The process by which organisms obtain energy directly from sunlight is called photosynthesis. • CO2 + H2O → C6H12O6 + O2

  4. ENERGY FOR LIFEPROCESSES • Autotrophs: most Plants, Algae, and some Bacteria. • Autotrophs store energy in various organic compounds, primarily carbohydrates.

  5. The Basic By McGraw Hill • Photosynthesis involves a complex series of chemical reactions: Biochemical Pathway • Products used in cellular respiration in both plants and animals.

  6. Redox Reactions: OIL RIGOxidation is LossReduction is Gain (of e-) or Oxidation is loss of hydrogen. Reduction is gain of hydrogen.

  7. How are they connected? +water+energyglucose+oxygen carbon dioxide glucose + oxygen  carbon + water+energy  C6H12O6 + 6O2 6CO2 + 6H2O + ATP dioxide light energy  6CO2 + 6H2O + + 6O2 C6H12O6 Heterotroph and…. oxidation = exergonic Autotroph reduction = endergonic

  8. glucose H2O CO2 N K P … What does it mean to be a plant ATP • Need to… • collect light energy • transform it into chemical energy • store light energy • in a stable form to be moved around the plant or stored • need to get building block atomsfrom the environment • C,H,O,N,P,K,S,Mg • produce all organic moleculesneeded for growth • carbohydrates, proteins, lipids, nucleic acids

  9. LIGHT ABSORPTION INCHLOROPLASTS • Light Reactions or Light Dependent Reactions • They begin with the absorption of light in chloroplasts. Review of the Light Reaction With All Details!

  10. CHLOROPLASTS

  11. LIGHT AND PIGMENTS

  12. chlorophylls accessory pigments carotenoids

  13. Photosynthesis gets energy by absorbing wavelengths of light. • Accessory pigments with different structures absorb light of different wavelengths: chlorophyll a & b, carotenoids, xanthophylls, antenna pigments

  14. What is Photosynthesis? • Light reactions • light-dependent reactions • convert solar energy to chemical energy • ATP & NADPH • Calvin cycle • light-independent reactions • sugar building reactions • uses chemical energy (ATP & NADPH) to reduce CO2 & synthesize C6H12O6 It’s not theDark Reactions!

  15. Virtual Cell Photo.

  16. LIGHT REACTIONS • ELECTRON TRANSPORT CHAIN: PHOTOSYSTEMS II AND I. • chlorophyll a P680 = absorbs 680nm wavelength red light chlorophyll b P700 = absorbs 700nm wavelength red light • REPLENISHING PHOTOSYSTEM II • CHEMIOSMOSIS Photosystem I Go to: D-Drive Youtube Streaming Video Photosystem I file b Virtual Cell:Photosynthesis

  17. ELECTRON TRANSPORT CHAIN The Basic Biochemical Pathway

  18. RESTORING PHOTOSYSTEM II

  19. CHEMIOSMOSIS

  20. NADP What is Photophosphorylation? cyclic photophosphorylation NONcyclic photophosphorylation ATP

  21. Why Cyclic Phosphorolation? • Calvin cycle uses more ATP than NADPH 18 ATP +12 NADPH 1 C6H12O6

  22. PUTTING IT ALL TOGETHER Overview Of the Light Reaction Review of the Light Reaction With All Details!

  23. Photosynthesis Animation • http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

  24. Experiment1 Experiment 2 light energy light energy light energy    6CO2 6CO2 6CO2 + + + 6H2O 6H2O 6H2O + + + + + + 6O2 6O2 6O2 C6H12O6 C6H12O6 C6H12O6 Experimental evidence • Where did the O2 come from? • radioactive tracer = O18 Proved O2 came from H2O not CO2 = plants split H2O!

  25. Photosynthesis summary Where did the energy come from? Where did the electrons come from? Where did the H2O come from? Where did the O2 come from? Where did the O2 go? Where did the H+ come from? Where did the ATP come from? What will the ATP be used for? Where did the NADPH come from? What will the NADPH be used for?

  26. So where does CO2 fit in? How do plants use it? Why do they need it?

  27. LIGHT INDEPENDENT REACTIONS Welcome to the Dark Side, Lord Calvin • KNOWN AS THE CALVIN CYCLE = C3 Photosynthesis. • CO2 IS FIXED INTO ORGANIC COMPOUNDS: CARBON FIXATION. • THREE MAJOR STEPS, WHICH OCCUR WITHIN THE STROMA. • Reduction Reaction= C gains H+ How do Plants Capture CO2? Calvin Cycle

  28. P.S. The Dark Cycle Does Not Happen in the Dark It is dependent on the products of the light reaction (ATP and NADPH) So when the lights go out…it has no energy to continue. NOVA Capturing C

  29. Think… • Why can’t we blow carbon emissions into forests and solve global warming?

  30. ALTERNATIVE PATHWAYSTO FIX CARBON • These alternative pathways are generally found in plants that evolved in hot, dry climates. • Stomata: passageways FOR CO2 and O2.

  31. C-4: Photosynthesis • Intense Sunlight and Hot (e.g. corn and crabgrass) • Stomata are Partly Closed During Day= CO2 falls and O2 rises • We don’t want photorespiration. • In the Mesophyll PEP carboxylase grabs CO2 not O2. • Sends CO2 to the Calvin cycle

  32. The C4 Pathway • FIXES CO2INTO A FOUR CARBON COMPOUND OXALOACETATE. HENSE THE NAME: C4 • Oxaloacetatein the mesophyll turns into Malate, an acid. • Malate is shipped through plasmodesmata into bundle sheath cells and release CO2 • Calvin Cycle Starts

  33. The CAM Plants Crassulacean Acid Metabolism • Adaptation to DryConditions • Stomata Closed during Day Open at Night • Mesophyll stores CO2 at night • Makes Sugar during Day • All 3 (C3, C-4, and CAM) use the Calvin Cycle

  34. The CAM Pathway • Plants that use the CAM pathway open their stomata at night and close them during the day—just the opposite of what other plants do.

  35. RATE OF PHOTOSYNTHESIS Review

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