Cellular and Molecular Biology

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Chloroplast Food Production


Chloroplasts utilize water and light to produce molecular oxygen. They utilize carbon dioxide to produce sugars.

The process by which chloroplasts produce sugars is called the


This process is

and has three reaction steps: fixation, reduction and regeneration.

The first step utilizes inorganic carbon dioxide and involves the carboxylation of ribulose-1,5-bisphosphate to produce 3-phosphoglyceric acid. This reaction is catalyzed by the enzyme,


In the second step,

, the energy carriers produced during light-dependent photosynthesis, are used to reduce 3-phosphoglyceric acid to glyceraldehyde 3-phosphate.

This step involves two reactions:
Firstly, 3-phosphoglyceric acid is

by the enzyme phosphoglycerate kinase and ATP, producing ADP and 1,3-bisphosphoglycerate.

Secondly, 1,3-bisphosphoglycerate is reduced by the enzyme glyceraldehyde 3-phosphate dehydrogenase and NADPH yielding NADP+ and glyceraldehyde 3-phosphate. Some of these glyceraldehyde 3-phosphates are utilized to produce


The third step involves a series of reactions to regenerate