During which phase of the Calvin cycle is ATP and NADPH used to convert 3-PGA into G3P?

The reduction phase of the Calvin cycle is where ATP and NADPH play crucial roles in converting 3-phosphoglycerate (3-PGA) into glyceraldehyde-3-phosphate (G3P). During this phase, energy and reducing power are supplied to the 3-PGA molecules. ATP is used to provide the necessary energy to activate the compounds, while NADPH donates high-energy electrons that help in the reduction of the 3-PGA. This process results in G3P, which is a three-carbon sugar and a key intermediate in the synthesis of glucose and other carbohydrates.

The reduction phase is vital because it transforms the initial products of carbon fixation into more energy-rich molecules. The G3P produced can either be utilized immediately in metabolic processes or, when combined with other G3P molecules, can be used to synthesize glucose and regenerate RuBP (ribulose bisphosphate) in subsequent steps of the cycle, facilitating the continuation of carbon assimilation in plants.