Pigments for PhotosynthesisPhotosynthesis in plants is dependent upon capturing light energy in the pigment chlorophyll, and in particular chlorophyll a. This chlorophyll resides mostly in the chloroplasts and gives leaves their green color. The range of light absorption in leaves is extended by some accessory pigments such as the carotenoids, but does not cover the entire visible range - that would make the leaves black! Some plants and plantlike organisms have developed other pigments to compensate for low light or poor use of light. Cyanobacteria and red algae have phycocyanin and allophycocyanin as accessory pigments to absorbe orange light. They also have a red pigment called phycoerythrin that absorbs green light and extends the range of photosynthesis. The red pigment lycopene is found in vegetables. Some red algae are in fact nearly black, so that increases their photosynthetic efficiency. Brown algae have the pigment fucoxanthin in addition to chlorophyll to widen their absorption range. These red and brown algae grow to depths around 270 meters where the light is less than 1% of surface light. But the most advanced plants are the land plants, which have the least advanced system for gathering light!
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Index Photosynthesis Concepts Reference Moore, et al. Ch 7 | ||
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Chlorophyll
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Accessory Pigments for PhotosynthesisChlorophylla-a is the primary pigment for photosynthesis in plants, but the range of light absorption is extended by chlorophyll-b, beta-carotene and other accessory pigments. The variations of chlorophyll-b and the bacterial version are indicated above. The range of light absorption is extended somewhat toward the middle of the visible spectrum by the content of carotenoids in leaves.
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Index Photosynthesis Concepts Reference Moore, et al. Ch 7 | ||
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CarotenoidsThe colors of the carotenoids are familiar as the fall colors of leaves. As the leaves lose their chlorophyll, the more persistent carotenoids give the pleasant reds, yellows and oranges of the autumn foliage. Beta-carotene is the most important of the carotenoids. Lycopene, the color of tomatoes, is also a carotenoid.
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Index Photosynthesis Concepts Reference Moore, et al. Ch 7 | ||
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Beta Carotene
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Lycopene
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Index Photosynthesis Concepts Reference Moore, et al. Ch 7 | |||
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