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Action spectrum

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 pig...

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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] It is related to absorption spectrum in many systems. Mathematically, it describes the inverse quantity of light required to evoke a constant response. It is very rare for an action spectrum to describe the level of biological activity, since biological responses are often nonlinear with intensity.

Action spectra are typically written as unit-less responses with peak response of one, and it is also important to distinguish if an action spectrum refers to quanta at each wavelength (mol or log-photons), or to spectral power (W).

It shows which wavelength of light is most effectively used in a specific chemical reaction. Some reactants are able to use specific wavelengths of light more effectively to complete their reactions. For example, chlorophyll is much more efficient at using the red and blue regions than the green region of the light spectrum to carry out photosynthesis. Therefore, the action spectrum graph would show spikes above the wavelengths representing the colours red and blue.

The first action spectrum was made by T. W. Engelmann, who split light into its components by the prism and then illuminated Cladophora placed in a suspension of aerobicbacteria. He found that bacteria accumulated in the region of blue and red light of the split spectrum. He thus discovered the effect of the different wavelengths of light on photosynthesis and plotted the first action spectrum of photosynthesis.[2]

Action spectra have a wide variety of uses in biological and chemical research, particularly in understanding the effect of ultraviolet (UV) light on biological molecules and systems. UV light wavelengths range between 295–400 nm and are known to induce skin and DNA damage.[3] As a result, action spectra have been used to measure the efficiency of different light wavelengths in disinfecting water, the rate and mechanism of photodegradation of folic acid in the blood, and the chirality of molecules to determine secondary structure. [4][5][6] Further examples include suppression of melatonin by wavelength[7] and a variety of hazard functions, related to tissue damage from visible and near-visible light.[8]

See also

References

  1. ↑Gorton HL (22 April 2010). "Biological Action Spectra". Photobiological Sciences Online. American Society for Photobiology. Retrieved 2020-01-18.
  2. ↑Kumar V. Question Bank in Biology for Class Xi (fourth ed.). Tata McGraw-Hill. p. 311. ISBN 978-0-07-026383-3.
  3. ↑Lawrence, Karl P.; Douki, Thierry; Sarkany, Robert P. E.; Acker, Stephanie; Herzog, Bernd; Young, Antony R. (2018-08-24). "The UV/Visible Radiation Boundary Region (385–405 nm) Damages Skin Cells and Induces "dark" Cyclobutane Pyrimidine Dimers in Human Skin in vivo". Scientific Reports. 8 (1): 12722. Bibcode:2018NatSR...812722L. doi:10.1038/s41598-018-30738-6. ISSN 2045-2322. PMC 6109054. PMID 30143684.
  4. ↑Sun, Wenjun; Jing, Zibo; Zhao, Zhinan; Yin, Ran; Santoro, Domenico; Mao, Ted; Lu, Zedong (2023-07-25). "Dose–Response Behavior of Pathogens and Surrogate Microorganisms across the Ultraviolet-C Spectrum: Inactivation Efficiencies, Action Spectra, and Mechanisms". Environmental Science & Technology. 57 (29): 10891–10900. Bibcode:2023EnST...5710891S. doi:10.1021/acs.est.3c00518. ISSN 0013-936X. PMID 37343195.
  5. ↑ Juzeniene, Asta; Thu Tam, Tran Thi; Iani, Vladimir; Moan, Johan (2013-09-05). "El espectro de acción para la fotodegradación del ácido fólico en soluciones acuosas" . Journal of Photochemistry and Photobiology B: Biology . 126 : 11–16 . Bibcode : 2013JPPB..126...11J . doi : 10.1016/j.jphotobiol.2013.05.011 . ISSN 1011-1344 . PMID 23892004 .  
  6. ↑ Barran, Perdita (26 de junio de 2020). "Espectros de acción de la estructura secundaria quiral" . Science . 368 (6498): 1426–1427 . Bibcode : 2020Sci...368.1426B . doi : 10.1126/science.abc1294 . ISSN 0036-8075 . PMID 32587006 .  
  7. ↑ Brainard GC, Hanifin JP, Greeson JM, Byrne B, Glickman G, Gerner E, Rollag MD (agosto de 2001). "Espectro de acción para la regulación de la melatonina en humanos: evidencia de un nuevo fotorreceptor circadiano" . The Journal of Neuroscience . 21 (16): 6405–12 . doi : 10.1523/JNEUROSCI.21-16-06405.2001 . PMC 6763155. PMID 11487664 .  
  8. ↑ Comisión Internacional de Protección contra las Radiaciones No Ionizantes. (julio de 2013). "Directrices de la ICNIRP sobre límites de exposición a la radiación visible e infrarroja incoherente" (PDF) . Health Physics . 105 (1): 74– 96. Bibcode : 2013HeaPh.105...74. . doi : 10.1097/HP.0b013e318289a611 . PMID 35606999 . 
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