Photosynthesis160-page13

Photosynthesis160-page13 - The Calvin cycle produces:...

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Photosynthesis - 13 The Calvin-Benson Cycle and Carbon Fixation The second set of reactions for photosynthesis is known as the Calvin cycle, or the light-independent reactions. They occur in the stroma region of the chloroplast and use the products formed during the light reactions of photosynthesis. All steps of the Calvin cycle are enzyme mediated. There are many parts to the Calvin cycle: Carbon Fixation Reduction Regeneration Surplus (Output) The requirements for the Calvin cycle are: Carbon dioxide (CO 2 ) NADPH from the light-dependent reactions (reducing power, source of electrons and the hydrogen source) ATP from the light-dependent reactions (energy source) Ribulose bisphosphate, regenerated in the cycle Appropriate enzymes for each step in the cycle. Of these, Ribulose bisphosphate carboxylase (Rubisco) is especially important. The Metabolic Intermediate in Process: G3P (Glyceraldehyde 3 Phosphate) (also called Phosphoglyceraldehyde – PGAL)
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Unformatted text preview: The Calvin cycle produces: Glucose (carbohydrate) as the typical end product Ribulose bisphosphate, regenerated in the cycle The details of the Calvin cycle were determined using radioisotopes of 14 C. The researchers (Calvin, Benson and others) won a Nobel prize for their discovery. To some extent, the Calvin cycle looks like a carbon cut-and-paste dance. Well, it is. It's easy to follow the maze if one counts carbons, even in more detail than presented in your text. It also helps to remember that without this happening, you'd starve! The typical Calvin cycle pathway is called 3-carbon photosynthesis (or C-3) because of the 3-Carbon intermediate that forms in CO 2 fixation. This is to distinguish it from an alternative photosynthetic pathway known as 4-carbon photosynthesis (or C-4), in which CO 2 is first trapped to form 4-carbon acids, a process to be discussed in a bit....
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This note was uploaded on 12/29/2011 for the course BIO 151 taught by Professor Edwards during the Spring '10 term at SUNY Stony Brook.

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