The chloroplast is the organelle that makes photosynthesis possible. Chloroplasts are found in plant cells and are responsible for the process of photosynthesis, which converts light energy into chemical energy. Chloroplasts contain chlorophyll, a green pigment that absorbs light energy from the sun. This light energy is used to split water molecules into hydrogen and oxygen atoms. The hydrogen atoms are then used to reduce carbon dioxide molecules into organic compounds, such as glucose. These organic compounds are used by the plant for growth and energy.