The dark reaction is known as carbon dioxide fixation, or the Calvin-Benson cycle . A common product is the sugar glucose . Additional anabolic steps can then convert the product to other organic classes such as protein or lipid. Ed. III, pp. Glucose contains six carbons.
Most life forms depend on catabolic pathways leading to the breakdown of glucose for energy release.
The beginning phase of the process is glycolysis or the Embden-Meyerhoff pathway . First, energy from ATP is required to energize the glucose. Another molecule of ATP is used in step 2. This places a strain on the bond between carbons 3 and 4. Step 3 leads to a break of this bond, thus the six-carbon glucose is split into two three carbon molecules.