= Calvin cycle
{c}
{wiki}
= Calvin-Benson cycle
{c}
{synonym}
The <Calvin cycle> couples <carbon fixation> to use of <ATP> and <NADPH>. In a <chloroplast> it takes place in the <chloroplast stroma>. Its <chemical reactions> incorporate <carbon dioxide>, use <NADPH>-supplied <Electrons>, and regenerate the <molecules> that accept further <carbon dioxide>.
In the standard <Calvin cycle> bookkeeping, three <carbon dioxide> <molecules> require nine <ATP> and six <NADPH> for one net three-<carbon> <triose phosphate>. A six-<carbon> <sugar> equivalent therefore corresponds to six <carbon dioxide>, eighteen <ATP> and twelve <NADPH>; subsequent <sugar> synthesis is separate. These are pathway requirements, not a universal measured <photosynthesis> yield. See https://openstax.org/books/biology-2e/pages/8-3-using-light-energy-to-make-organic-molecules[OpenStax Biology 2e, 8.3: Calvin cycle bookkeeping].
Calling the <Calvin cycle> light-independent means its individual <chemical reactions> do not directly capture <light>; it does not mean the <Calvin cycle> runs only at night or independently of the supplies from <light-dependent reactions>.
Back to article page
