The role of the thylakoid membranes in chloroplasts is crucial for the process of photosynthesis. Thylakoids contain chlorophyll, the pigment responsible for capturing light energy from the sun. This energy is used in the light-dependent reactions of photosynthesis to convert water and carbon dioxide into glucose and oxygen. Additionally, the thylakoid membranes create a proton gradient that is essential for producing ATP through chemiosmosis. This makes thylakoids vital for energy transformation in plants.