Q. In the Calvin cycle for the fixation of 5 molecules of CO2, how many ATP and NADPH are required in the reduction step?
Solution:
The three steps of the Calvin cycle are:
1. Carboxylation – the most critical step of the Calvin cycle where the CO2 is utilized for the carboxylation of RuBP. This response is catalyzed by way of the enzyme RuBP carboxylase which results in the formation of molecules of 3-PGA.
2. Reduction – the step utilizes two molecules of ATP for phosphorylation and two of NADPH. The fixation of six molecules of CO2 and 6 turns of the cycle is required for the elimination of one molecule of glucose from the pathway. The reduction of one molecule of CO2 to carbohydrate requires a minimum of 8 quanta of light.
3. Regeneration – the CO2 acceptor molecule RuBP is critical if the cycle is to preserve uninterrupted. The regeneration steps require one ATP for phosphorylation to shape RuBP.
Since, fixing one molecule of CO2, 3 ATP and 2 NADPH are required in the reduction step. Hence, for the fixation of 5 molecules of CO2, 15 ATP, and 10 NADPH are required in the reduction step.
1. Carboxylation – the most critical step of the Calvin cycle where the CO2 is utilized for the carboxylation of RuBP. This response is catalyzed by way of the enzyme RuBP carboxylase which results in the formation of molecules of 3-PGA.
2. Reduction – the step utilizes two molecules of ATP for phosphorylation and two of NADPH. The fixation of six molecules of CO2 and 6 turns of the cycle is required for the elimination of one molecule of glucose from the pathway. The reduction of one molecule of CO2 to carbohydrate requires a minimum of 8 quanta of light.
3. Regeneration – the CO2 acceptor molecule RuBP is critical if the cycle is to preserve uninterrupted. The regeneration steps require one ATP for phosphorylation to shape RuBP.
Since, fixing one molecule of CO2, 3 ATP and 2 NADPH are required in the reduction step. Hence, for the fixation of 5 molecules of CO2, 15 ATP, and 10 NADPH are required in the reduction step.