Pseudocyclic photophosphorylation

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Megha bhargava 11:03, 10 March 2007 (UTC) Pseudocyclic Photophosphorylation

"pseudo" meaning false, this gives a slight idea of what pseudocuclic photophosphorylation is, but, some workers believe that cyclic photophosphorylation is simply an artifact of the preparations studied in the laboratory. They think that the deficit is made up instead by a process called pseudocyclic photophosphorylation in which some of the electrons passing to ferredoxin then reduce molecular oxygen back to H2O instead of reducing NADP+ to NADPH.

At first glance, this might seem a fruitless undoing of all the hard work of photosynthesis. But look again. Although the electrons cycle from water to ferredoxin and back again, part of their pathway is through the chemiosmosis-generating stem of cytochrome b6/f.

Here, then, is another way that simply by turning on a light, enough energy is imparted to electrons that they can bring about the synthesis of ATP.

Antenna Pigments

Chlorophylls a(C55H72O5N4Mg A magnesium chelate of dihydroporphyrin)and b (C55H70O6N4Mg An ester similar to chlorophyll a but with a CHO substituted for a CH3) differ slightly in the wavelengths of light that they absorb best (although both absorb red and blue much better than yellow and green). Carotenoids help fill in the gap by strongly absorbing green light. The entire complex ensures that most of the energy of light will be trapped and passed on to the reaction center chlorophylls.