noun Botany, Biochemistry.
- the green coloring matter of leaves and plants, essential to the production of carbohydrates by photosynthesis, and occurring in a bluish-black form, C55H72MgN4O5 (chlorophyll a), and a dark-green form, C55H70MgN4O6 (chlorophyll b).
- the green pigment of plants and photosynthetic algae and bacteria that traps the energy of sunlight for photosynthesis and exists in several forms, the most abundant being chlorophyll a (C 55 H 72 O 5 N 4 Mg): used as a colouring agent in medicines or food (E140)
green-colored stuff in plants, 1819, from French chlorophyle (1818), coined by French chemists Pierre-Joseph Pelletier (1788-1842) and Joseph Bienaimé Caventou (1795-1877) from Greek khloros “pale green” (see ) + phyllon “a leaf” (see ).
- Any of a group of related green pigments found in photosynthetic cells that converts light energy into ATP and other forms of energy needed for biochemical processes; it is found in green plants, brown and red algae, and certain aerobic and anaerobic bacteria.
- Any of several green pigments found in photosynthetic organisms, such as plants, algae, and cyanobacteria. At its molecular core, chlorophyll has a porphyrin structure but contains a magnesium atom at its center and a long carbon side chain. Chlorophyll absorbs red and blue wavelengths of light, but reflects green. When it absorbs light energy, a chlorophyll molecule enters a higher energy state in which it easily gives up an electron to the first available electron-accepting molecule nearby. This electron moves through a chain of acceptors and is ultimately used in the synthesis of ATP, which provides chemical energy for plant metabolism. Plants rely on two forms of chlorophyll, chlorophyll a (C66H72MgN4O5) and chlorophyll b (C66H70MgN4O6), which have slightly different light absorbing properties. All plants, algae, and cyanobacteria have chlorophyll a, since only this compound can pass an electron to acceptors in oxygen-producing photosynthetic reactions. Chlorophyll b absorbs light energy that is then transferred to chlorophyll a. Several protist groups such as brown algae and diatoms lack chlorophyll b but have another pigment, chlorophyll c, instead. Other closely related pigments are used by various bacteria in photosynthetic reactions that do not produce oxygen. See more at photosynthesis.
The complex chemical that gives a plant its green color and plays an important role in the conversion of sunlight into See .)for the plant. (