what are accessory pigments?
Accessory pigments are light-absorbing compounds, found in photosynthetic organisms, that work in conjunction with chlorophyll a. They include other forms of this pigment, such as chlorophyll b in green algal and higher plant , while other algae may contain chlorophyll c or d. In addition, there are many non-chlorophyll accessory pigments, such as carotenoids or phycobiliproteins which also absorb light and transfer that light energy to photosystem chlorophyll. Some of these accessory pigments, particularly the carotenoids, also serve to absorb and dissipate excess light energy, or work as antioxidants. The different chlorophyll and non-chlorophyll pigments associated with the photosystems all have different 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 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 phycobiliproteins that absorb green light reaching these habitats. For more kindly click on the links below --- en.wikipedia.org/wiki/Accessory_p... en.wikipedia.org/wiki/Photosynthe...
