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C4 photosynthesis
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C4 photosynthesis

C4 photosynthesis is a common metabolic pathway found in land plants living under arid conditions. CAM plants utilize a similar process. It is called "C4" because the product, oxaloacetate, contains four carbon atoms. It occurs in the mesophyll of the leaf. The chemical equation is:

PEP carboxylase + PEP + CO2 → oxaloacetate

The product is usually converted to malate, a simple organic compound that gives up its CO2 to the Calvin cycle after being shipped off to bundle sheath cells surronding a nearby vein. After losing the CO2, it becomes pyruvate, and can be phophorylatedd into PEP at the cost of a phosphorus group and one ATP. It can then be reused in the above equation.