Chloroplasts are organelles found in plant cells and some other eukaryotic organisms. Their functions include conducting photosynthesis, and in some algae, lipid synthesis. They carry out all fatty acid synthesis in plants, and are involved in a plant's immune response. Photosynthesis is their main function, where chloroplasts capture the sun's light energy, and store it in the energy storage molecules ATP and NADPH while freeing oxygen from water. They then use the ATP and NADPH to make organic molecules from carbon dioxide in a process known as the Calvin cycle.