Here's what goes into the Calvin cycle:
Inputs:
* Carbon dioxide (CO2): The primary source of carbon atoms for building sugars.
* ATP: Energy currency of the cell, produced during the light-dependent reactions.
* NADPH: Electron carrier, also produced during the light-dependent reactions, carrying reducing power (high-energy electrons).
Key Steps:
1. Carbon Fixation: CO2 is incorporated into an existing 5-carbon molecule called RuBP (ribulose bisphosphate) by the enzyme RuBisCO. This forms an unstable 6-carbon molecule that quickly breaks down into two 3-carbon molecules called 3-PGA (3-phosphoglycerate).
2. Reduction: ATP and NADPH are used to convert 3-PGA into G3P (glyceraldehyde 3-phosphate). This step requires energy from ATP and reducing power from NADPH.
3. Regeneration: Some G3P molecules exit the cycle to be used for building sugars (glucose), while the rest are used to regenerate RuBP, the starting molecule. This process consumes ATP and involves a series of complex enzymatic reactions.
Outputs:
* Glucose (C6H12O6): A simple sugar, the primary product of photosynthesis.
* ADP (adenosine diphosphate): The energy currency of the cell after ATP has been used.
* NADP+ (nicotinamide adenine dinucleotide phosphate): The oxidized form of NADPH, ready to be reused in the light-dependent reactions.
In Summary:
The Calvin cycle takes in carbon dioxide, ATP, and NADPH, uses them to create glucose, and regenerates RuBP to continue the cycle. This process essentially converts light energy into chemical energy stored in the bonds of glucose.
