The main class of photosynthetic pigments. They absorb red and blue-violet light and thus reflect green light, so giving plants their characteristic green colour. Chlorophylls are involved in the light reactions of photosynthesis and are located in the chloroplast. The molecule consists of a planar porphyrin 'head' and a long phytol 'tail' (see diagram). A molecule of magnesium is present in the centre of the porphyrin ring. In vivo the chlorophyll molecule is bound to membrane proteins via the phytol chain. Its function in photosynthesis is to absorb light energy and initiate electron transport. There are four groups of chlorophylls: a, b, c, and d. Chlorophyll a is found in all autotrophic plants, chlorophyll b in the Chlorophyta, Charophyta, and land plants, and chlorophylls c and d only in certain algae. See also bacteriochlorophyll
The structure of chlorophyll a.