Steps for the Calvin Cycle in Chloroplasts

The Calvin cycle uses ATP and NADPH from the light reactions to convert CO2 into glucose. This is an endergonic reaction.

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Rubisco (enzyme) combines 1 RuBP with 1 CO2. This forms a 6-carbon molecule!

This 6-carbon molecule is split into 2 3PG molecules (3 carbons each = 6 total) that reduce to 2 G3P molecules.

With each 3PG reduced to G3P, an ATP and NADPH are used, simultaneously producing an ADP and NADP+

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For every 6 CO2 that enter the Calvin cycle, 12 G3P are formed. 2 G3P are used to produce 1 glucose and the other 10 G3P are used to regenerate RuBP. RuBP is now ready to bind another CO2 and run the Calvin cycle again!

The regeneration of RuBP requires additional ATP not shown in my picture.

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CO2 = 1 carbon Glucose = 6 carbons

Therefore, we need 6 CO2 (= 6 Calvin cycles) to make one glucose molecule!