Water - Water The electron that was lost from the antenna...

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Water The electron that was lost from the antenna complex of photosystem I is replaced by splitting water (see diagram above). In the light reactions, electrons move one way from water to NADPH and the energy of sunlight is used to produce ATP . Calvin Cycle (Light-independent Reactions) The products of the light reactions (ATP and NADPH) are used to reduce CO 2 to carbohydrate in the Calvin cycle. The words "CO 2 fixation" refer to the attachment of CO 2 to an organic compound: each CO 2 binds to a 5-carbon ribulose biphosphate (RuBP ) molecule. Carbon dioxide fixation is catalyzed by RuBP carboxylase ( rubisco ). The diagram below shows that six carbon dioxide molecules are combined with six RuBP molecules to produce six molecules of a 6-carbon compound. Each of the carbon dioxide molecules contains one carbon atom and each RuBP molecule contains 5 for a total of 6 carbons. Rubisco makes up 20 - 50% of the protein in chloroplasts. It acts very slowly, catalyzing 3 molecules per second. This compares to 1000 per second for typical enzymatic reactions. Large
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quantities are needed to compensate for its slow speed. It may be the most abundant
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This note was uploaded on 11/10/2011 for the course BIOLOGY bi 101 taught by Professor - during the Fall '10 term at Montgomery.

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Water - Water The electron that was lost from the antenna...

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