Plant cells and eukaryotic algae have chloroplasts, which are photosynthesis-conducting organelles. Chloroplasts capture light and combine it with water and carbon dioxide gas to keep the plant alive. Photosynthesis is the conversion of light energy from the sun into free energy stored in ATP and NADPH by chloroplasts. Chloroplasts are one of the body's many different organelles, and they're thought to have evolved from cyanobacterial endosymbiosis. In this way, they're comparable to mitochondria, although they're only found in plants and protists.