photosynthesis Biochemistry. Netsiklichesky fotofosforilirovanie and oxygen allocation

you are: photosynthesis Biochemistry

When ustitsa sheet are opened, and hloroplasty absorb mixed light of different lengths of waves, simultaneously with photosystem I the photosystem II joins also. In a combination with each other they make system not cyclic fotofosforilirovanija. In these conditions activated elektrony, given P700, are transferred at first on FeS, and then on ferredoksin. In this point they deviate a cyclic way and are transferred - through various flavoproteidy - on NADP +, niatsinsoderzhashchee the connection, the restored which form (NADPH) is used in the subsequent reactions for restoration РЎРћ2 to level of carbohydrates. Now the chlorophyll of a power trap photosystems II, Р 680, also passes in the raised condition and gives elektron. Having passed through a number of carriers (plastohinon, cytochrome f, plastotsianin), this elektron eventually reaches Р 700 and fills here ' a hole ', arisen when this system, having passed in the raised condition as a result of light absorption, has lost elektron. Р 680, entering into photosystem II, in turn fills the hole formed in it, attaching elektron from an ion It - a product of ionisation of water. Apparently, two arisen such way ' a free radical ' (20N-) unite and form peroxide which eventually breaks up, as leads to oxygen allocation. For this reaction of allocation of oxygen are necessary in quality kofaktorov manganese and chlorine ions, and ingibitorom it synthetic herbicide diuron (dihlorfenildimetilmochevina) can serve. The plants processed diuronom, perish, possibly, as a result of accumulation of peroxide or any others vysokookislennyh connections. Besides, carrying over elektronov from water is thus blocked, not formed ATR and not restored NADP +. Diuron, hence, it is toxic only for green plants on light; for other organisms including for the person, it, apparently, is harmless.

At water ionisation are formed also ions N +. They remain in the water тилакоидов Õ½В'Г“В'»½áßÔВ'Гі environment consisting as we remember, not only from water molecules, but also from N + - and It - of ions. However accumulation N of +-ions on a membrane inside tilakoidov plays a part in formation ATR (see more low). On photosystems are transferred only given by a chlorophyll elektrony though protons (N +-ions) take place together with elektronami a way part on a chain of carriers. when two elektrona join in final, the account to NADP +, from the water environment surrounding tilakoidnye membranes, free protons are taken and by such way is formed NADPH. All this process presented on fig. 4.12, has received the name ' Z-schemes '.