Chlorophyl
The chlorophyl (made up word in 1817 starting from the Greek roots grc χλωρός chlorós : green and grc φύλλον phýllon : break into leaf) is the principal pigment assimilator of the higher plants.
Isolated in 1817 by Joseph Bienaimé Caventou, this pigment, located in the Chloroplast S of the vegetable cells, intervenes in the Photosynthèse to intercept luminous energy, first stage in the conversion of this energy into chemical energy. Its absorption spectrum of the light radiation is responsible for the green color of the plants: the least absorptive wavelength is the green, it is thus this color which is perceived. There exist several differentiable chlorophyl shapes according to their chemical structure. Chlorophyl has exists at all the plants ( ≈ 2 g/kg of fresh sheets ) and chlorophyl B is at Cormophytes (higher plants) and Chlorophycées (green algas) with less contents ( ≈ 0.75 g/kg MF ). Two other alternatives exist at Phéophycées (brown algas) and unquestionable Cyanobactéries, respectively chlorophyls C and D .
Chlorophyl is also strongly reflective in the infra-red close relation (700 Nm), the air stereotypes false colors (IR + green + blue) make it possible to the specialists to recognize the gasolines by radiometric analysis.
Chemical structure and biosynthesis
Chlorophyl is a Chlorine (four cores pyrroles in circle), chelating a magnesium atom in the center, as well as an alcohol with long chain, phytol (except for chlorophyl C ). It has a structure quasi-identical to the Hème (present in the blood red globules). It is the presence, in its structure, of many doubles combined connections which allows an interaction with the light radiation and its absorption. The side chains of chlorine are variable and this involves a modification of the absorption spectrum between the various families of chlorophyls.
A magnesium deficit in the ground thus affects directly the biosynthesis of chlorophyls, the quantity of pigment manufactured will be weak and them (new) sheets will be green-pale, even yellows. A manifestation of the deficiency (more or less marked) out of minerals affecting the final content chlorophyl is called Chlorose.
Chlorophyl, slightly water soluble, is on the other hand much more in ethanol.
Absorption spectrum
The Visible spectrum is located roughly between 380 Nm at 780 Nm although a range of 400 Nm with 700 Nm is more common. The light perceived like “Green E” by the eye and the human Cerveau has a wavelength, according to the notions of the “green” color, roughly between 500 and 565 Nm.
One notices on the graph that the absorptance of chlorophyl is less for this beach of the electromagnetic Specter. Chlorophyl thus absorbs the major part of the visible spectrum except the green light.
Experimental description
One can show that chlorophyl is necessary for photosynthesis by using a sheet of a mixed plant (the white parts of the sheet are deprived of chlorophyl) where the starch beforehand will have been digested. After an exposure of a few hours to the light and the use of an iodized solution, a black coloring appears only on the zones which were green and contained chlorophyl.This second experiment makes it possible to observe chlorophyl in the sheets and to see what would have the air a sheet without its chlorophyl. To carry out this experiment, you will need: of a pan, grips, of glass, a tepid container of water, alcohol with friction (isopropanol or isopropanol) and of a quite green sheet (it is preferable to use leafy trees). Start by making boil water in the pan. You need little water, a few centimetres at the bottom of the pan are enough. Extinguish fire and put your sheet to soak a few seconds (30 to 60 second maximum). Withdraw to it water with grips. Delicately place your sheet in glass. Cover your alcohol sheet with friction. Let put back glass during one hour in a tepid water dish.
Simple: Chlorophyll
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