Calvin Cycle Aims to convert chem. Energy energy in glucose (ATP + NADPH). Discovered by Calvin & Benson through C14 to track process. C3: Oxygen problem arises because Rubisco attaches to oxygen slowing down photosynthesis by 50% and performing an operation called photorespiration. When stomata are closed it does not take in as much CO 2 , so Rubisco attaches to the O 2 available because of this. This process didn’t happen in early Earth b/c there was more CO 2 available and plants only perform Photorespiration as a protective role to neutralize the damaging costs of the light reaction. RUBP + O 2 2-C sugar CO 2 (wastes resources and energy to produce CO 2 and NOT sugar). 3-carbon sugar can go 3 ways: Primary adds ATP to catalyze regeneration of Rubisco, Secondary sucrose transported out of chloroplast during the day, and thirdly, at night, stomata are closed no CO 2 , no calvin cycle, stored as starch breaking down to sucrose Phloem and distributed throughout plant. C4: PEP carboxylase stores CO 2 as inorganic compounds inside PEP which has a higher affinity for CO 2 than O 2 . Calvin Cycle occurs in Bundle Sheath Cells. Occurs in 2 cells in response to higher temps Closed stomata CO 2 outcompetes O 2 for Rubisco. CAM: Collect CO 2 at night and store as organic acids inside the vacuoles to be used during the day so that the stomata can remain closed. This conserves water and prevents CO
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