Where do light-dependent reactions occur in the chloroplast?

Light-dependent reactions take place in the thylakoid membranes of the chloroplasts. These reactions involve the absorption of light energy, which is captured by chlorophyll and other pigments located within the thylakoid structures. When light is absorbed, it energizes electrons that initiate the process of photosynthesis, leading to the production of ATP and NADPH, which are used in the subsequent light-independent reactions.

The thylakoid membranes contain the necessary components, including the protein complexes that participate in the electron transport chain and the light-harvesting complexes. This is where water (H2O) is split to release oxygen as a byproduct, and the ATP synthase enzyme synthesizes ATP when protons flow back across the thylakoid membrane.

The stroma, while crucial for the Calvin cycle (light-independent reactions) where carbon fixation occurs, is not where the light-dependent reactions happen. The outer membrane and the chlorophyll itself do not conduct these reactions either. Thus, the thylakoid membranes serve as the crucial site for capturing light energy and producing the energy-rich compounds required for the overall process of photosynthesis.