Cell Biology


Cell Brochure
Diffusion Lab
Osmosis Lab
DNA Replication

Cell Biology Facts

Student Objectives
Cell Theory
Cell Structure
Cell Membranes
Cellular Transport
Cellular Respiration
Anaerobic Respiration
Aerobic Respiration
Calvin Cycle
DNA Replication

Cell Biology Sites

The Dark Reaction
Photosynthesis: Pathway of Carbon Fixation
The Calvin Cycle. The Conneticut River Home Page
The Calvin-Benson Cycle


Light and photosynthesis in aquatic ecosystems, by John T.O. Kirk. 1983. Cambridge Univ. Press.

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Cell Biology

Calvin Cycle

The following formula summarizes the Calvin cycle.

C5 + CO2 + ATP + NADPH ---> C6H12O6

where C5 is a fivecarbon molecule, such as pyruvate, when is recycled as glucose is synthesized. The Calvin cycle is the last step in photosynthesis. The purpose of the Calvin Cycle is to take the energy from photosystem I and fix carbon. Carbon fixation means building organic molecules by adding carbon onto a chain. In order to do this, you have to start with an organic molecule, a starter molecule. In this case, the starter molecule is a 5-chain carbon compound (C5). I'll skip the names of most of the organic molecules in this process. We'll cover it in AP Biology.

The first step in the Calvin cycle is for the 3C5 to bind with 3CO2, producing a six 3-carbon organic molecules (6C3). Next, 6ATP and 6NADPH energizes the binding of a C3 to make a 6-carbon molecule (C6), glucose. The remaining 5C3 continues moving through the Calvin cycle, being turned back into the starter C5 organic molecule.

The following chemical equation summarizes the Calvin cycle.