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Photosynthesis

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Photosynthesis

Postby |sirius| » Wed Mar 29, 2006 2:37 am

Can CAM photosynthesis and C4 photosynthesis occur simultaneously in one plant in different cells?
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Postby |sirius| » Wed Mar 29, 2006 5:18 am

I have another question too. How much ATP is made from the light reactions of photosynthesis? I know that for 4 photons of light (2 at each photosystem), 1 NADPH + H+ is made, but I don't know how much ATP is made.

I'll be very grateful for any help I can get on either of my two questions. Thanks in advance.
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Postby MrMistery » Wed Mar 29, 2006 6:16 pm

For the first post: NO
For the second: The same. In non-cyclic electron flow from 4 electrons you have one NADPH molecule and one ATP molecule.
Take notice however, that because the Calvin cycle uses more ATP than NADPH, cyclic electron flow occurs..
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Postby Mjhavok » Sat Apr 01, 2006 7:53 pm

Here is a link that explains cyclic and non cyclic photosynthesis is a small animation

"http://highered.mcgraw-hill.com/sites/0072437316/student_view0/chapter10/animations.html"
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Postby Trev » Sat Apr 01, 2006 8:34 pm

|sirius| wrote:I have another question too. How much ATP is made from the light reactions of photosynthesis?


In the light reactions of photosynthesis ATP is NOT formed.

As you now, photosyntheisis consist from two stage: light reactions and dark reactions. The first phase is connected with division of charge, when chlorophyll converts to excite status by photon.
Second stage (dark reations) is connected to biochemical reactions, when ATP and NADP are formed.
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Postby MrMistery » Sun Apr 02, 2006 8:28 pm

Go read a textbook Trev and you will see how wrong you are. In the light reactions of photosynthesis ATP and NADPH(Not NADP, which by the way doesn't exist) by acyclic and cyclic electron flow.
During the dark reaction(which by the way is a bad name, since some enzymes need blue light as information source)also known as the Calvin-Bensen cycle or the carbon assimilation phase, ATP and NADPH are used to reduce CO2 to organic molecules, using the energy from the ATP and the NADPH created in the light phase. From 3 molecules of CO2 the Calvin cycle is able to make a molecule of glyceraldehide-phosphate, which then fuses with a brother of his to make a fructose-6-phosphate molecule.

You were saying? ;)
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Postby Mjhavok » Sun Apr 02, 2006 11:43 pm

Nicotinamide adenine dinucleotide phosphate(NADP) does exist, its an important CoEnzyme.
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Postby Trev » Mon Apr 03, 2006 10:09 am

MrMistery wrote:Go read a textbook Trev and you will see how wrong you are. In the light reactions of photosynthesis ATP and NADPH(Not NADP, which by the way doesn't exist) by acyclic and cyclic electron flow.
...
You were saying? ;)


uuupps)))))) I wasn`t right, yes =) I have not watched to the end the sentence. its stupid) terrible sorrrrry)
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Postby MrMistery » Mon Apr 03, 2006 5:09 pm

@Mjhavok
Nicotinamide adenine dinucleotide phosphate does exist. But it is NADP+
The "+" part is very important, because it tells you that NADP can accept 2 protons and only one electron. Unlike FAD, that has no "+" and can accept an equal number of electrons and protons(2).

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