Any member of one of the most important classes of pigment molecules involved in photosynthesis .
Found in almost all photosynthetic organisms, it consists of a central magnesium atom surrounded by a nitrogen-containing structure called a porphyrin ring, to which is attached a long carbon-hydrogen side chain, known as a phytol chain. In structure it is remarkably similar to hemoglobin . Chlorophyll uses energy that it absorbs from light to convert carbon dioxide to carbohydrates. In higher plants it is found in chloroplasts .