BIOL 1106 Chapter Notes - Chapter 40: Phytochrome, Phototropism, Photosynthetic Efficiency
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These both compensate for the plant"s inability to walk away from unfavorable environmental conditions. Phytochrome r absorbs red light and phytochrome fr absorbs far-red light (longer wavelength). Pr is inactive and turns into pfr when red photons are present. Degradation by ubiquitin tagging pfr for transport to the proteasome regulates the amount of pfr; Chromophore (part of phytochrome sensitive to light) and apoprotein (helps with expression of light-response genes). Phytochrome is found in cytoplasm but enters nucleus to facilitate transcription of light-response genes; pr is moved into nucleus after turning into pfr. Both phytochrome and chlorophyll are pigments that have multiple forms and absorb red light. Phytochrome uses light as a source of information while chlorophyll uses light as a source of energy. Many growth responses are linked to phytochrome action. Phytochrome is involved in plant growth responses such as seed germination, shoot elongation, and detection of crowding by plants.