Chlorophyll gives most green plants their characteristic color and absorbs light for photosynthesis. It is found in chloroplasts, specialized structures inside plant cells and many algae.
Plants use chlorophyll mainly in two forms, chlorophyll a and chlorophyll b. Chlorophyll a is directly involved in the light-dependent reactions of photosynthesis, while chlorophyll b helps broaden the range of light that can be captured. Both absorb blue and red light more strongly than green light, which is reflected to our eyes.
During photosynthesis, absorbed light energy helps convert carbon dioxide and water into chemical energy stored in sugars. Oxygen is released as a by-product when water molecules are split.
Chlorophyll is not the only pigment in leaves. Carotenoids absorb additional wavelengths and become especially visible in autumn when chlorophyll breaks down. The word “chlorophyll” comes from Greek roots meaning “green” and “leaf,” but several photosynthetic organisms contain related chlorophyll molecules.