Transduction (biophysics)
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2008-06-09T10:00:45Z
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In [[biophysics]], '''transduction''' is the conveyance of energy from one [[electron]] (a donor) to another (a receptor), at the same time that the class of energy changes.
Photonic energy, the [[kinetic energy]] of a [[photon]], may follow the following paths:
* be released again as a photon of less energy;
* be transferred to a recipient with no change in class;
* be dissipated as heat; or
* be transduced
In [[photosynthesis]], when the electrons of the "[[chlorophyll]] pair" receive the photon energy from the "collecting" associated [[pigments]], the photonic energy is "destined" to link one molecule of [[phosphate]] to one of [[Nicotinamide adenine dinucleotide|NAD]]. The resulting [[Nicotinamide adenine dinucleotide|NADP]] in turn will use the stored energy in the generation of [[adenosine triphosphate|ATP]], which is the end point of the light-induced photosynthetic process. This means that the photon's energy ends up its circuit by being ''transduced'' to an electron that takes part in the formation of a molecular link of energy-rich phosphate.
In the pathway of this end-point transduction, the energy is ''transferred'' along a number of molecules ([[cytochrome]]s), in a downward way so that energy is partially ''dissipated'' at each step. The liberated heat energy serves the [[homeostasis]] of the plant, and at the end of the chain the remaining energy is perhaps exactly the one that is needed to build NADP.
This process is committed; i.e. there is no return path. Homeostasis, theoretically, might save the day only at the beginning: before the luminic energy transferred to the "chlorophyl pair" is conveyed to the first element of the cytochrome chain, there is a gap in the process when the energy is carried as a series of ''excitons''. These are now called ''resonant-energy-transferring'' molecules of the chlorophyll class, which transfer what is considered electromagnetic energy, from one to its neighbor with no participation of electrons nor enzymes. At this stage, if the first pigment has received an excess of light, the "exciton" perhaps might ''dissipate'' the energy as heat.
[[Category:Biophysics]]