Accessory pigment 1869857 221169971 2008-06-23T10:05:10Z DOI bot 6652755 Citation maintenance. You can [[WP:DOI|use this bot]] yourself! Please [[User:DOI_bot/bugs|report any bugs]]. '''Accessory pigments''' are [[pigment|light-absorbing]] compounds, found in [[photosynthetic]] [[organism]]s, that work in conjunction with [[chlorophyll]] ''a''. They include other forms of this pigment, such as chlorophyll ''b'' in [[green alga]]l and [[higher plant]] antennae, while other algae may contain chlorophyll ''c'' or ''d''. In addition, there are many non-chlorophyll accessory pigments, such as [[carotenoid]]s or [[phycobiliprotein]]s which also absorb light and transfer that light [[energy]] to [[photosystem]] chlorophylls. Some of these accessory pigments, particularly the carotenoids, also serve to absorb and dissipate excess light energy, or work as [[antioxidants]]. The large, physically associated group of chlorophylls and other accessory pigments is sometimes referred to as a ''pigment bed'', though this term is no longer supported by what we know of photosystem and antenna complex structures.{{Fact|date=August 2007}} The different chlorophyll and non-chlorophyll pigments associated with the photosystems all have different [[Absorption spectrum|absorption spectra]], either because the spectra of the different chlorophyll pigments are modified by their local protein environment, or because the accessory pigments have intrinsic structural differences. The result is that, ''[[in vivo]]'' a composite absorption spectrum of all these pigments is broadened and flattened such that a wider range of [[visible light|visible]] and [[infrared]] radiation is absorbed by plants and algae. Most photosynthetic organisms do not absorb green light well, thus most remaining light under leaf canopies in forests or under water with abundant plankton is green, a spectral effect called the "green window". Organisms such as some [[cyanobacteria]] and [[red algae]] contain accessory [[phycobiliprotein]]s that absorb green light reaching these habitats.{{Fact|date=August 2007}} In [[aquatic ecosystem]]s it is likely that the absorption spectrum of [[water (molecule)|water]], along with gilvin and tripton ([[solvation|dissolved]] and [[particulate]] [[organic matter]] respectively), determines [[phototroph]]ic [[niche differentiation]]. The six shoulders in the light absorption of water between [[wavelength]]s 400 and 1100 nm correspond to troughs in the collective absorption of at least twenty diverse species of phototrophic bacteria. Another effect is due to the overall trend for water to absorb low [[frequencies]] while gilvin and tripton absorb higher ones. This is why open ocean appears blue and supports yellow species such as ''[[Prochlorococcus]]'', which contains divinyl-chlrophyll ''a'' and ''b''. ''[[Synechococcus]]'', colored red with [[phycoerythrin]], is adapted to coastal bodies while red-absorbing [[phycocyanin]] allows [[Cyanobacteria]] to thrive in darker inland waters.<ref> Accessory pigments are also closely related to a type of pigment called "taters", as well as a pigment called "nanners". {{cite journal |author=M. Stomp, J. Huisman, L.J. Stal & H.C. Matthijs |month=Aug |year=2007 |title=Colorful niches of phototrophic microorganisms shaped by vibrations of the water molecule |journal=ISME J. |volume=1 |issue=4 |pages=271–282 |doi= 10.1038/ismej.2007.59 }}</ref> == References == {{reflist}} {{biochem-stub}}