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But once a red photon has been absorbed, the pigment undergoes a rapid conformational change to form the P fr state. Here fr indicates that now not red but far-red (also called "near infra-red"; 705–740 nm) is differentially absorbed. This shift in absorbance is apparent to the human eye as a slightly more greenish color.
Phytochrome is the only known photoreceptor that absorbs light in the red/far red spectrum of light (600-750 nm) specifically and only for photosensory purposes. [1] Phytochromes are proteins with a light absorbing pigment attached called a chromophore. The chromophore is a linear tetrapyrrole called phytochromobilin. [7]
A reaction center comprises several (about 25-30) [6] protein subunits, which provide a scaffold for a series of cofactors. The cofactors can be pigments (like chlorophyll, pheophytin, carotenoids), quinones, or iron-sulfur clusters. [7] Each photosystem has two main subunits: an antenna complex (a light harvesting complex or LHC) and a ...
Phycoerythrin (PE) is a red protein-pigment complex from the light-harvesting phycobiliprotein family, present in cyanobacteria, [1] red algae [2] and cryptophytes, [3] accessory to the main chlorophyll pigments responsible for photosynthesis.The red pigment is due to the prosthetic group, phycoerythrobilin, which gives phycoerythrin its red color.
Chlorophyll is any of several related green pigments found in cyanobacteria and in the chloroplasts of algae and plants. [2] Its name is derived from the Greek words χλωρός (khloros, "pale green") and φύλλον (phyllon, "leaf"). [3]
This pair of chlorophyll molecules, often called the "special pair", absorbs photons at 870 nm or 960 nm, depending on the species and, thus, is called P870 (for Rhodobacter sphaeroides) or P960 (for Blastochloris viridis), with P standing for "pigment"). Once P absorbs a photon, it ejects an electron, which is transferred through another ...
The antenna-shaped light harvesting complex of cyanobacteria, glaucocystophyta, and red algae is known as the phycobilisome which is composed of linear tetrapyrrole pigments. Pigment-protein complexes referred to as R-phycoerythrin are rod-like in shape and make up the rods and core of the phycobilisome. [16]
The absorbance pattern responsible for the red color of anthocyanins may be complementary to that of green chlorophyll in photosynthetically active tissues such as young Quercus coccifera leaves. It may protect the leaves from attacks by herbivores that may be attracted by green color.