Light-dependent reactions occur in the thylakoid membranes of the chloroplasts, specifically within the grana, which are stacks of thylakoids. These reactions involve pigment molecules like chlorophyll that absorb light energy to drive the production of ATP and NADPH. The thylakoid membrane houses the photosystems (PSI and PSII), electron transport chains, and ATP synthase necessary for these processes. During these reactions, water molecules are split to release oxygen, and the energy from light is converted into chemical energy stored in ATP and NADPH, which are then used in the light-independent reactions (Calvin cycle) occurring in the stroma of the chloroplast