The Calvin cycle is the light-independent phase of photosynthesis that takes place in the stroma of chloroplasts and is responsible for the fixation of atmospheric carbon dioxide into carbohydrates. It uses the ATP and NADPH produced during the light reactions to drive a series of enzyme-mediated steps that ultimately lead to the synthesis of sugars. The cycle is broadly divided into three main phases: carboxylation, reduction, and regeneration of the carbon dioxide acceptor. The first step of the Calvin cycle is carboxylation. In this step, carbon dioxide combines with a five-carbon sugar called ribulose-1,5-bisphosphate (RuBP). This reaction is catalyzed by the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, commonly known as RuBisCO, which is the most abundant enzyme in the biosphere. The unstable six-carbon compound formed immediately breaks down into two molecules of a three-carbon compound, 3-phosphoglyceric acid (3-PGA). For every three molecules of CO₂ entering the cycle, three molecules