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Non-Cyclic Phosphorylation of Photosynthesis

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Jan31-11, 12:37 PM
P: 52
1. The problem statement, all variables and given/known data
Dear All,

I would like to ask you a question as the concept doesn't seem to be best explained on my book.

It is stated that during non-cyclic phosphorylation two electrons (One per molecule of Chlorophyll in the reaction center.) leave PSI, travel an electron transport chain and final reach one final protein (ferredoxin) which is reduced. (For a total of two ferredoxin molecules reduced, one per electron.), these proteins are then used to reduce NADPH+ to NADPH+H+. It is also stated that should there be no NADPH+ available the electrons will cycle the electron transport chain again to produce ATP.

Is ATP produced also the first time electrons travel the electron transport chain after leaving PhotostemI?

Is ATP produced as in the first step, with Hydrogen Ions being pumped inside the thylakoid, hence producing a proton gradient, and ATP Synthase taking advantage of this potential to recharge ATP?

Also, if I understood correctly the Cholorophyll in PSII loses two electrons twice, for a total of four electrons loss, hence giving it the ability to the split a water molecule producing some additional protons as well as stabilizing itself. Does the same happen in PSI even though each Chlorophyll loses only one electron?

Are the protons pumped into the thylakoid as a result of ETC post PSII the same ones which have been produced by lysis of water or were they simply floating around in the chloroplast?

2. Relevant equations

3. The attempt at a solution
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