Figure 1. A variety of chlorophyll/carotenoid-binding LHCs and phycobilisomes are associated with reaction centres of photosystem I (RC1) and II (RC2): in cyanophytes (e.g. Synechococcus) phycobilisomes transfer energy initially to RC2, and LHCs are lacking; rhodophytes (e.g. Porphyridium) have Chl a/car LHCs associated only with RC1, and phycobilisomes only with RC2. In chlorophytes (e.g. Pisum) distinct Chl a/b/car LHCs are associated with each RC. In chromophytes (e.g. Cylindrotheca) distinct Chl a/c-car LHCs occur with RC1 and RC2. In cryptophytes (e.g. Cryptomonas) phycobiliproteins in the lumen transfer energy to Chl a, but not to Chl c. Both Chl types are associated with RC1 and RC2. Dinophytes (e.g. Gonyaulax) have a luminal peridinin–Chl a complex and an integral Chl a/c complex in thylakoids.

Figure 2. Molecular structures of chlorophylls and photosynthetically important carotenoids. Portions highlighted in red indicate the specific side-chains of the individual chlorophylls, and the differences between lutein, peridinin and fucoxanthin.

Figure 3. Photosynthetic pigments absorb in the visible range of the electromagnetic spectrum. (a) Spectra of chlorophylls a and b (in acetone), c₁ (in diethyl ether), and d (in acetone). (b) Spectra of phycobiliproteins B-PE (phycoerythrin), PC (phycocyanin) and APC (allophycocyanin) (in 0.1 mol L^–1 phosphate buffer). These water-soluble pigments are present in many rhodophytes and cyanobacteria. Lutein (in acetone) is a common carotenoid in green plants.