Identify the main inputs and outputs of the Calvin cycle and explain the roles of Rubisco, NADPH and ATP in this series of reactions.

The Calvin cycle, also known as the light-independent or dark reactions, is the second stage of photosynthesis that occurs in the stroma of the chloroplasts. It uses the energy stored in ATP and NADPH during the light-dependent reactions to convert carbon dioxide into glucose.

The main inputs of the Calvin cycle are carbon dioxide (CO2), ATP (adenosine triphosphate), and NADPH (nicotinamide adenine dinucleotide phosphate). The main outputs are glucose (a type of sugar), ADP (adenosine diphosphate), NADP+ and inorganic phosphate (Pi).

1. Role of Rubisco: Rubisco (Ribulose-1,5-bisphosphate carboxylase/oxygenase) is an enzyme that catalyzes the first major step of the Calvin cycle, the fixation of carbon dioxide. It combines CO2 with ribulose-1,5-bisphosphate (RuBP), a 5-carbon sugar, to form a 6-carbon compound that immediately splits into two 3-carbon compounds known as 3-phosphoglycerate (3-PGA).

2. Role of NADPH: NADPH provides the electrons and protons (hydrogen) needed to reduce 3-PGA into glyceraldehyde 3-phosphate (G3P), a 3-carbon sugar. This is the part of the cycle known as reduction. Some of the G3P molecules are used to make glucose, while others are recycled to regenerate RuBP.

3. Role of ATP: ATP provides the energy needed for the regeneration of RuBP from G3P, allowing the cycle to continue. This is the part of the cycle known as regeneration.

In summary, the Calvin cycle uses CO2, ATP, and NADPH to produce glucose, ADP, NADP+, and Pi. Rubisco, NADPH, and ATP play crucial roles in this process by catalyzing the fixation of CO2, providing electrons and protons for the reduction of 3-PGA, and supplying energy for the regeneration of RuBP, respectively.