PHOTOSYNTHESIS REACTIONS Photosynthesis takes place in two stages. In the First stage, called the Light reactions, the light energy is used to convert ADP and Phosphates to ATP. In addition, in the predominant form of the light-dependent reactions, the electron carrier NADP + is reduced to NADPH. The coenzyme NADPH, like NADH, is an energy- rich carrier of electrons. In the Second stage, the light-independent (Dark) reactions, these electrons are used along with energy from ATP to reduce CO 2 to Carbohydrate sugar. LIGHT REACTION (or) LIGHT DEPENDENT REACTION (or) PHOTOPHOSPHORYLATION Photophosphorylation is one of the three ways ATP is formed, and it occurs only in photosynthetic cells. In this mechanism, Light energy is absorbed by Chlorophyll molecules in the photosynthetic cell, exciting some of the molecules electrons. The Chlorophyll is located in the membranous Thylakoids of Chloroplasts in Algae and Green plants. In Cyanobacteria, Thylakoids are found in the photosynthetic ...