Calvin Cycle
Calvin Cycle Overview <ul><li>Calvin cycle is a cyclical process which: </li></ul><ul><li>Fixes carbon (make C-C bonds) </...
Calvin Cycle <ul><li>occurs in the stroma of chloroplast </li></ul><ul><li>reactions are not as linear as Krebs  </li></ul>
Calvin Cycle: Carbon Fixation <ul><li>three CO 2  (1 carbon) are attached to three  1,5-ribulose bisphosphate  (5 carbon) ...
Rubisco <ul><li>r ib u lose  bis phosphate  c arboxylase /  o xygenase </li></ul><ul><li>large, slow reacting enzyme </li>...
Calvin Cycle:  Energy Utilization <ul><li>ATP phosphorylates each 3-carbon molecule </li></ul><ul><li>rxn type:  phosphory...
Calvin Cycle: Energy Utilization <ul><li>NADPH used to synthesize  G3P </li></ul><ul><li>rxn type:  redox </li></ul><ul><l...
Calvin Cycle:  Regenerate Molecules <ul><li>5 G3P and ATP to resynthesize 1,5-ribulose bisphosphate </li></ul><ul><li>1 G3...
Calvin Cycle Review <ul><li>6 turns of the Calvin cycle to fix 6 CO 2  molecules </li></ul><ul><li>18 ATP & 12 NADPH molec...
 
Factors Overview <ul><li>light intensity, [CO 2 ] and temperature </li></ul><ul><li>C3 plant limitations </li></ul><ul><li...
Photosynthesis Rate Photosynthesis Rate
Photosynthesis Rate Factors <ul><li>increased [CO 2 ] = increased photosynthesis </li></ul><ul><li>increased temperature =...
C3 Plant Limitations <ul><li>C3 plants undergo photosynthesis as described </li></ul><ul><li>stomata are open during the d...
 
C3 Plant Limitations <ul><li>In hot, arid conditions, plants close the stomata and increases [O 2 ] within the cells.  </l...
C4 Plant Adaptation <ul><li>adaptation to hot, arid environments </li></ul>e.g.  corn, sugarcane, grasses
C4 Plant Adaptation <ul><li>C4 plants have a special  mesophyll cell & bundle-sheath cell  structure. </li></ul><ul><li>Me...
CAM(crassulacean acid metabolism) Plant Adaptation <ul><li>adaptation to hot, arid environments </li></ul><ul><li>e.g.  ca...
CAM Plant Adaptation <ul><li>CO 2  collected & incorporated into organic molecules at night </li></ul><ul><li>CO 2  releas...
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10 calvin cycle-plant limitations-2010 stacy

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10 calvin cycle-plant limitations-2010 stacy

  1. 2. Calvin Cycle
  2. 3. Calvin Cycle Overview <ul><li>Calvin cycle is a cyclical process which: </li></ul><ul><li>Fixes carbon (make C-C bonds) </li></ul><ul><li>Utilizes energy molecules </li></ul><ul><li>Regenerates molecules for another cycle </li></ul>
  3. 4. Calvin Cycle <ul><li>occurs in the stroma of chloroplast </li></ul><ul><li>reactions are not as linear as Krebs </li></ul>
  4. 5. Calvin Cycle: Carbon Fixation <ul><li>three CO 2 (1 carbon) are attached to three 1,5-ribulose bisphosphate (5 carbon) </li></ul><ul><li>three 6-carbon molecule are split into six 3-carbon molecules </li></ul>rxn type: synthesis enzyme: synthase ( Rubisco ) energy: absorbed
  5. 6. Rubisco <ul><li>r ib u lose bis phosphate c arboxylase / o xygenase </li></ul><ul><li>large, slow reacting enzyme </li></ul><ul><ul><li>most enzymes process 1000 reactions / second </li></ul></ul><ul><ul><li>rubisco processes 3 reactions / second </li></ul></ul><ul><li>plants need large amounts of rubisco for Calvin cycle </li></ul><ul><ul><li>half the protein in a leaf </li></ul></ul><ul><ul><li>most abundant protein on Earth </li></ul></ul>
  6. 7. Calvin Cycle: Energy Utilization <ul><li>ATP phosphorylates each 3-carbon molecule </li></ul><ul><li>rxn type: phosphorylation </li></ul><ul><li>enzyme: kinase </li></ul><ul><li>energy: absorbed </li></ul>
  7. 8. Calvin Cycle: Energy Utilization <ul><li>NADPH used to synthesize G3P </li></ul><ul><li>rxn type: redox </li></ul><ul><li>enzyme: dehydrogenase </li></ul><ul><li>energy: absorbed </li></ul>
  8. 9. Calvin Cycle: Regenerate Molecules <ul><li>5 G3P and ATP to resynthesize 1,5-ribulose bisphosphate </li></ul><ul><li>1 G3P used in another pathway </li></ul><ul><li>rxn type: synthesis </li></ul><ul><li>enzyme: synthase </li></ul><ul><li>energy: absorbed </li></ul>
  9. 10. Calvin Cycle Review <ul><li>6 turns of the Calvin cycle to fix 6 CO 2 molecules </li></ul><ul><li>18 ATP & 12 NADPH molecules used </li></ul><ul><li>electrons from 10 H 2 O transferred through the light reactions </li></ul>
  10. 12. Factors Overview <ul><li>light intensity, [CO 2 ] and temperature </li></ul><ul><li>C3 plant limitations </li></ul><ul><li>C4 plants </li></ul><ul><li>CAM plants </li></ul>
  11. 13. Photosynthesis Rate Photosynthesis Rate
  12. 14. Photosynthesis Rate Factors <ul><li>increased [CO 2 ] = increased photosynthesis </li></ul><ul><li>increased temperature = increased photosynthesis </li></ul><ul><li>increased light intensity = increased photosynthesis </li></ul><ul><ul><li>only to a certain plateau since Calvin cycle cannot keep up with the light reactions </li></ul></ul>
  13. 15. C3 Plant Limitations <ul><li>C3 plants undergo photosynthesis as described </li></ul><ul><li>stomata are open during the day / closed at night </li></ul><ul><li>What happens to stomata in hot, arid conditions? </li></ul>
  14. 17. C3 Plant Limitations <ul><li>In hot, arid conditions, plants close the stomata and increases [O 2 ] within the cells. </li></ul><ul><li>At high [O 2 ], rubisco binds to O 2 rather than CO 2 in the process of photorespiration that causes the plant to skip the Calvin cycle. Glucose is not produced. </li></ul><ul><li>This is detrimental to agricultural crops. </li></ul><ul><ul><li>rice, wheat, soy </li></ul></ul>
  15. 18. C4 Plant Adaptation <ul><li>adaptation to hot, arid environments </li></ul>e.g. corn, sugarcane, grasses
  16. 19. C4 Plant Adaptation <ul><li>C4 plants have a special mesophyll cell & bundle-sheath cell structure. </li></ul><ul><li>Mesophyll cells create 4-carbon molecules using PEP carboxylase and release CO 2 into the bundle-sheath cells. </li></ul><ul><li>Bundle-sheath cells only perform the Calvin cycle. </li></ul><ul><li>In hot, arid conditions, C4 cells provide enough CO 2 to ensure rubisco does not bind to O 2 molecules. </li></ul>
  17. 20. CAM(crassulacean acid metabolism) Plant Adaptation <ul><li>adaptation to hot, arid environments </li></ul><ul><li>e.g. cactus, pineapples (water storing plants) </li></ul><ul><li>Stomata are closed in the day and open at night. </li></ul>
  18. 21. CAM Plant Adaptation <ul><li>CO 2 collected & incorporated into organic molecules at night </li></ul><ul><li>CO 2 released from the organic molecules during the day where ATP & NADPH is produced to allow the Calvin cycle to proceed </li></ul>

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