Kloropil: Béda antarrépisi
Konten dihapus Konten ditambahkan
Baris ka-4:
== Kloropil jeung potosintésis ==
Kloropil penting pisan dina [[potosintésis]], nyaéta pikeun nyerep [[énérgi]] [[cahya]]. Molekul kloropil ayana dina kompléks [[protéin]] pigmén nu katelah [[potosistim]], nu nangkod dina mémbran [[tilakoid]] [[kloroplas]]. Dina kompléks ieu, kloropil boga dua pancén: nyerep cahya jeung ngamalirkeun énérgina maké jalan [[alih énérgi résonans]] ka pasangan kloropil husus di [[puseur réaksi]] dina potosistim.
The function of the reaction center chlorophyll is to use the energy absorbed by and transferred to it from the other chlorophyll pigments in the photosystems to undergo a charge separation, a specific [[redox]] reaction in which the chlorophyll donates an [[electron]] into a series of molecular intermediates called an [[electron transport chain]]. The charged reaction center chlorophyll (P680<sup>+</sup>) is then reduced back to its ground state by accepting an electron. In Photosystem II, the electron which reduces P680<sup>+</sup> ultimately comes from the oxidation of water into O<sub>2</sub> and H<sup>+</sup> through several intermediates. This reaction is how photosynthetic organisms like plants produce O<sub>2</sub> gas, and is the source for practically all the O<sub>2</sub> in Earth's atmosphere. Photosystem I typically works in series with Photosystem II, thus the P700<sup>+</sup> of Photosystem I is usually reduced, via many intermediates in the thylakoid membrane, by electrons ultimately from Photosystem II. Electron transfer reactions in the thylakoid membranes are complex, however, and the source of electrons used to reduce P700<sup>+</sup> can vary. The electron flow produced by the reaction center chlorophyll pigments is used to shuttle H<sup>+</sup> ions across the thylakoid membrane, setting up a [[chemiosomosis|chemiosmotic]] potential mainly used to produce [[Adenosine triphosphate|ATP]] chemical energy, and those electrons ultimately reduce NADP<sup>+</sup> to [[NADPH]] a universal [[redox|reductant]] used to reduce CO<sub>2</sub> into sugars as well as for other biosynthetic reductions.
Baris ka-17:
Some plants have variegated leaves with white and green areas. Take such a plant and put it in the dark for a few days. Take a leaf and make a "mask" to cover it out of aluminium foil. Cut two holes (one round, one square)in the foil such that one hole exposes a green part of the leaf and the other a white part of the leaf. Place the leaf in the light for an hour or so. If the leaf is exposed to a solution of iodine the green part of the leaf exposed to the light will show up black and the white part will not stain black. Furthermore, the black patch will have the same shape as the hole that you had cut in the foil. The iodine-stained starch only piles up in areas of the leaf that were green, showing that only those areas are photosynthetic. This proves that photosynthesis doesn't occur in the areas where there was no chlorophyll.
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== Wangun kimia ==
Kloropil téh pigmén [[klorin]] nu wangunna sarta dijieunna sarupa jeung pigmén [[porfirin]] séjén kawas [[hémé]]. Di tengah cingcin porfirin aya [[ion]] [[magnésium]], sedengkeun ranté gigirna mah bisa béda-béda, tapi ilaharna mah ngandung ranté [[pitol]]. Aya sababaraha bentuk kloropil nu aya di alam:
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