Chlorophyll is a pigment found in plants which absorb sunlight.
Chlorophyll (also chlorophyl) is any of several related green pigments found in cyanobacteria and the chloroplasts of algae and plants.[1] Its name is derived from the Greek words χλωρός, chloros ("green") and φύλλον, phyllon ("leaf").[2] Chlorophyll is essential in photosynthesis, allowing plants to absorb energy from light.
Chlorophylls absorb light most strongly in the blue portion of the electromagnetic spectrum as well as the red portion.[3] Conversely, it is a poor absorber of green and near-green portions of the spectrum, which it reflects, producing the green color of chlorophyll-containing tissues. Two types of chlorophyll exist in the photosystems of green plants: chlorophyll a and b
History
Chlorophyll was first isolated and named by Joseph Bienaimé Caventou and Pierre Joseph Pelletier in 1817.[5] The presence of magnesium in chlorophyll was discovered in 1906,[6] and was the first time that magnesium had been detected in living tissue.[7]
After initial work done by German chemist Richard Willstätter spanning from 1905 to 1915, the general structure of chlorophyll a was elucidated by Hans Fischer in 1940. By 1960, when most of the stereochemistry of chlorophyll a was known, Robert Burns Woodward published a total synthesis of the molecule.[7][8] In 1967, the last remaining stereochemical elucidation was completed by Ian Fleming,[9] and in 1990 Woodward and co-authors published an updated synthesis.[10] Chlorophyll f was announced to be present in cyanobacteria and other oxygenic microorganisms that form stromatolites in 2010;[11][12] a molecular formula of C55H70O6N4Mg and a structure of (2-formyl)-chlorophyll a were deduced based on NMR, optical and mass spectra.[
Photosynthesis
Chlorophyll is vital for photosynthesis, which allows plants to absorb energy from light.[14]
Chlorophyll molecules are arranged in and around photosystems that are embedded in the thylakoid membranes of chloroplasts.[15] In these complexes, chlorophyll serves three functions. The function of the vast majority of chlorophyll (up to several hundred molecules per photosystem) is to absorb light. Having done so, these same centers execute their second function: the transfer of that light energy by resonance energy transfer to a specific chlorophyll pair in the reaction center of the photosystems. This pair effects the final function of chlorophylls, charge separation, leading to biosynthesis. The two currently accepted photosystem units are photosystem II and photosystem I, which have their own distinct reaction centres, named P680 and P700, respectively. These centres are named after the wavelength (in nanometers) of their red-peak absorption maximum. The identity, function and spectral properties of the types of chlorophyll in each photosystem are distinct and determined by each other and the protein structure surrounding them. Once extracted from the protein into a solvent (such as acetone or methanol),[16][17][18] these chlorophyll pigments can be separated into chlorophyll a and chlorophyll