Photosynthesis

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Photosynthesis

  1. 1. Photosynthesis By: Matt Goebel, Julia Douglas, Brandon Schroeder, and Courtney Rodgers
  2. 2. Structure of Chloroplasts <ul><li>Chloroplast envelope: double membrane </li></ul><ul><li>Internal membranes -> Tykaloids </li></ul><ul><li>Stroma: clear fluid around tykaloids </li></ul><ul><li>Grana: stacks of tykaloids </li></ul>
  3. 3. Photosynthesis <ul><li>Light energy into chemical energy </li></ul><ul><ul><li>Occurs in Chloroplasts (or prokaryotic equivalent) </li></ul></ul><ul><li>Light from sun has range of wavelengths </li></ul><ul><li>-Different colors </li></ul>
  4. 4. Photosynthesis <ul><li>Chlorophyll are the main photosynthetic pigment </li></ul><ul><ul><li>Light is trapped here </li></ul></ul><ul><ul><li>Embedded in the Chloroplast’s membrane </li></ul></ul><ul><li>Different colors, different absorption from chlorophyll </li></ul><ul><li>Remaining colors reflected back </li></ul><ul><ul><li>green leaves </li></ul></ul>
  5. 5. Absorption <ul><li>All chlorophyll absorb red & blue </li></ul><ul><li>Measured in Photons </li></ul><ul><ul><li>Pigment absorbs photon through electrons </li></ul></ul><ul><ul><li>Too much energy/ not enough energy and the energy can't be absorbed </li></ul></ul><ul><ul><li>Electron at high energy level is called an excited electron </li></ul></ul><ul><li>Accessory pigments absorb other wavelengths and then transfers them to chlorophyll </li></ul>
  6. 6. Action Spectrum <ul><li>Rate of absorption </li></ul>
  7. 7. Absorption Spectra <ul><li>% of absorbancy </li></ul>
  8. 8. Photosynthesis <ul><li>Light energy used to produce ATP and split water molecule </li></ul><ul><ul><li>Light captured by Chlorophyll </li></ul></ul><ul><ul><li>Light energy trapped into Chemical energy (electrons) </li></ul></ul><ul><ul><li>Chemical energy used to form ATP </li></ul></ul><ul><ul><li>Split water molecule used for: </li></ul></ul><ul><ul><ul><li>Organic molecules (Ex. Glucose) </li></ul></ul></ul><ul><ul><ul><li>Oxygen given off </li></ul></ul></ul>
  9. 9. Photosynthesis <ul><li>Hydrogen combined with carbon dioxide used to form organic compounds (Ex. Sugar) </li></ul><ul><ul><li>Bonds formed by energy from ATP </li></ul></ul><ul><ul><li>Different combinations of C, H, O and N </li></ul></ul><ul><ul><li>Plants are able to form all the organic compounds they need </li></ul></ul>
  10. 10. Photosynthesis <ul><li>Photosynthesis can be measured by: </li></ul><ul><ul><li>Depletion of substrate </li></ul></ul><ul><ul><ul><li>Because: rate of photosynthesis changes, the measure of water/carbon dioxide being used changes </li></ul></ul></ul><ul><ul><li>Increase in biomass </li></ul></ul><ul><ul><ul><li>Because: rate of photosynthesis changes, rate of organic molecules created change, biomass change </li></ul></ul></ul>
  11. 11. Photosynthesis <ul><li>Factors affecting photosynthesis: </li></ul><ul><ul><li>Temperature </li></ul></ul><ul><ul><li>Light Intensity </li></ul></ul><ul><ul><li>Carbon Dioxide Concentration </li></ul></ul><ul><li>Temperature affects photosynthesis </li></ul><ul><ul><li>Increases with kinetic energy of reactants </li></ul></ul><ul><ul><li>Maximum at “optimal” temperature </li></ul></ul><ul><ul><li>Decreases as enzymes begin to denature </li></ul></ul>
  12. 12. Photosynthesis <ul><li>Carbon Dioxide Concentration </li></ul><ul><ul><li>As the CO2 increases, so does the reaction </li></ul></ul><ul><ul><li>Maximum rate of photosynthesis is reached </li></ul></ul><ul><ul><li>Saturation point with CO2 is met and no longer affects plant’s rate of photosynthesis </li></ul></ul>
  13. 13. Photosynthesis <ul><li>Light Intensity </li></ul><ul><ul><li>At low levels, photosynthesis cant occur at high rate </li></ul></ul><ul><ul><li>Increase in light intensity, increase rate of photosynthesis </li></ul></ul><ul><ul><li>Light intensity keeps increasing until rate of photosynthesis can’t increase anymore </li></ul></ul><ul><ul><li>Too high intensity can damage cell </li></ul></ul>
  14. 14. Limiting Factors <ul><li>Only 1 factor actually limits photosynthesis </li></ul><ul><ul><li>Factor furthest from optimum </li></ul></ul><ul><li>Factors: </li></ul><ul><ul><li>Light intensity </li></ul></ul><ul><ul><li>Carbon Dioxide concentration </li></ul></ul><ul><ul><li>Temperature </li></ul></ul>
  15. 15. Light-dependent reactions <ul><li>Light-dependent reactions MUST have light </li></ul><ul><li>2 parts: </li></ul><ul><ul><li>Photosystem II </li></ul></ul><ul><ul><li>Photosystem I </li></ul></ul>
  16. 16. Photosystem II <ul><li>Electron acceptor: accepts excited electrons from chlorophyll </li></ul><ul><ul><li>Plastoquinne (hydrophobic) </li></ul></ul><ul><li>Accepts 2 electrons and becomes reduced plastoquinne </li></ul><ul><li>Causes photolysis of water </li></ul><ul><ul><li>Generates Oxygen </li></ul></ul><ul><li>Reduced plastoquinne has energy for photosynthesis </li></ul>
  17. 17. Photophoshorylation & Chemiosmosis <ul><li>Photophoshorylation </li></ul><ul><ul><li>ATP from light energy </li></ul></ul><ul><ul><li>Main = non-cyclic </li></ul></ul><ul><ul><li>Energy pumps proteins across tykaloid membrane </li></ul></ul><ul><li>Chemiosmosis </li></ul><ul><ul><li>Proteins travel back over gradient </li></ul></ul><ul><ul><li>ATP becomes ADP </li></ul></ul><ul><ul><li>Plastocyanin takes electrons </li></ul></ul>
  18. 18. Photosystem I <ul><li>Product is NADPH </li></ul><ul><li>Electrons are photoactivated </li></ul><ul><ul><li>Electrons are passed along chain of freedoxin (protein) </li></ul></ul><ul><li>Electron from photosystem I replaced by electrons from plastocyanin </li></ul><ul><ul><li>Used to reduce NADP </li></ul></ul><ul><li>Electrons move back up chain -> ATP </li></ul>
  19. 19. Light-Independent Reactions <ul><li>Don’t use light </li></ul><ul><li>Calvin cycle </li></ul><ul><ul><li>Occurs in stroma </li></ul></ul><ul><ul><li>Uses excited electrons </li></ul></ul><ul><ul><li>Carbon dioxide and water to organic compounds </li></ul></ul><ul><ul><li>Produces: glyceraldehyde-3-phosphate, 3 ADP, and 2 NADP + </li></ul></ul>
  20. 20. Light-Independent Reactions
  21. 21. <ul><li>Have a nice day!!! </li></ul>

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