Chlorophyll a chemical energy but is not the only pigment that can be used for photosynthesis. All oxygenic photosynthetic organisms use chlorophyll "a", but differ in accessory pigments like chlorophylls "b". Chlorophyll "z" can also be found in very small quantities in the green sulfur bacteria, an anaerobic photoautotroph. These organisms use bacteriochlorophyll and some chlorophyll "a" but do not produce oxygen. Anoxygenic photosynthesis is the term applied to this process, unlike oxygenic photosynthesis where oxygen is produced during the light reactions of photosynthesis. The molecular structure of chlorophyll "a" consists of a chlorin ring, whose four nitrogen atoms surround a central
Chlorophyll c Chlorophyll c Chlorophyll "c" is a form of chlorophyll found in certain marine algae, including the photosynthetic Chromista (e.g. diatoms, brown algae) and dinoflagellates. It has a blue-greenish color and is an accessory pigment, particularly significant in its absorption of light in the 447-452 nm wavelength region, Like chlorophyll a and chlorophyll b, it helps the organism gather light and passes a quanta of excitation energy through the light harvesting antennae to the photosynthetic reaction centre. Chlorophyll "c" is unusual because it has a porphyrin ring structure and does not have an isoprenoid tail or a reduced ring D, features