Calvin cycle
Britishnoun
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A series of chemical reactions that occurs as part of the dark reactions of photosynthesis, in which carbon is broken away from gaseous carbon dioxide and fixed as organic carbon in compounds that are ultimately used to make sugars and starch as food. The Calvin cycle starts with a five-carbon sugar molecule, to which the carbon of carbon dioxide is attached by a covalent bond. This unstable molecule breaks apart into two three-carbon molecules, which are reduced by the electron-carriers ATP and NADPH (which were created by the earlier light reactions) into three-carbon molecules that are available for the synthesis of sugar and starch. It takes three carbon dioxide molecules to produce enough carbon for the synthesis of one of these three-carbon molecules and to regenerate the five-carbon sugar so the cycle can begin again.
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See more at photosynthesis
Etymology
Origin of Calvin cycle
C20: named after Melvin Calvin , who elucidated it
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
Gagrani points to earlier research by Smith and colleagues on the Calvin cycle, the series of reactions in photosynthesis that converts carbon dioxide into glucose.
From Science Daily ● Jan. 6, 2026
The organic acid is stored until the next day and is then broken down releasing carbon dioxide that can be fixed by rubisco and enter the Calvin cycle to make sugars.
From Textbooks ● Jan. 1, 2015
The CO2 is then fixed by rubisco and made into sugars via the Calvin cycle, exactly as in C3 photosynthesis.
From Textbooks ● Jan. 1, 2015
Initial carbon fixation takes place in mesophyll cells and the Calvin cycle takes place in bundle-sheath cells.
From Textbooks ● Jan. 1, 2015
Instead of separating the light-dependent reactions and the use of CO2 in the Calvin cycle in space, CAM plants separate these processes in time.
From Textbooks ● Jan. 1, 2015
Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023
Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.
