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Absorbance spectra of free chlorophyll a (blue) and b (red) in a solvent. The action spectra of chlorophyll molecules are slightly modified in vivo depending on specific pigment-protein interactions. An action spectrum is a graph of the rate of biological effectiveness plotted against wavelength of light. [1]
Photosynthetically active radiation (PAR) spans the visible light portion of the electromagnetic spectrum from 400 to 700 nanometers. Photosynthetically active radiation (PAR) designates the spectral range (wave band) of solar radiation from 400 to 700 nanometers that photosynthetic organisms are able to use in the process of photosynthesis.
This mismatch between absorption spectra and photochemical action plots has by now been observed in a wide array of photoreactive systems. [41] [42] [43] A prominent example is the photoinduced [2+2] cycloaddition of the stilbene derivative, styrypyrene, which exhibited an 80 nm discrepancy between the action plot and absorption spectrum. [33]
Oat phytochrome absorption spectrum (Devlin, 1969). Phytochromes are a class of photoreceptor proteins found in plants, bacteria and fungi.They respond to light in the red and far-red regions of the visible spectrum and can be classed as either Type I, which are activated by far-red light, or Type II that are activated by red light. [2]
Photobiology is the scientific study of the beneficial and harmful interactions of light (technically, non-ionizing radiation) in living organisms. [1] The field includes the study of photophysics, photochemistry, photosynthesis, photomorphogenesis, visual processing, circadian rhythms, photomovement, bioluminescence, and ultraviolet radiation effects.
Phototropism in Solanum lycopersicum. In biology, phototropism is the growth of an organism in response to a light stimulus. Phototropism is most often observed in plants, but can also occur in other organisms such as fungi. The cells on the plant that are farthest from the light contain a hormone called auxin that reacts when phototropism ...
The natural ("wild-type") ChR2 absorbs blue light with an absorption and action spectrum maximum at 480 nm. [14] When the all-trans-retinal complex absorbs a photon, it induces a conformational change from all-trans to 13-cis-retinal. This change introduces a further one in the transmembrane protein, opening the pore to at least 6 Å.
The action spectrum for this quenching process suggested the involvement of carotenoids, [10] and the specific involvement of the OCP was later demonstrated by Kirilovsky and coworkers in 2006. [11] In 2008, OCP was shown to require photoactivation by strong blue-green light for its photoprotective quenching function. [ 12 ]