- The Calvin
The Calvin Cycle involves the fixation and reduction of Carbon, Its as
easy as 1,2,3.
|1. Carbon is Fixed
CO2 + RuBP -> 2 PGA molecules (1 + 5 = 2
X 3) Animation
2. The phosphoglyceric acid is reduced (using NADPH) to phosphoglyceraldehyde.
3. The fixed, reduced Carbon is rearranged to make Glucose
and regenerate RuBP.
with the phosphorylated 5-carbon sugar ribulose bisphosphate
- This reaction is catalyzed
by the enzyme ribulose bisphosphate carboxylase oxygenase (RUBISCO
an enzyme which can fairly claim to be the most abundant protein on
- The resulting 6-carbon compound
down (real fast) into two molecules of
3-phosphoglyceric acid (PGA)
- The PGA molecules are further
phosphorylated (by ATP) and are reduced (by NADPH) to form
phosphoglyceraldehyde (G3P, also called PGAL)
- Phosphoglyceraldehyde serves
as the starting material for the synthesis of glucose and fructose,
or it can be used to
make more RuBP.
- Glucose and fructose make
the disaccharide sucrose, which travels in solution to other
parts of the plant (e.g., fruit, roots) or
is used in the synthesis of the polysaccharides starch
rich molecules were formed during the Light reactions of Photosynthesis.
This is the 5-Carbon
molecule to which Carbon (CO2) is fixed.
can be used to form Glucose or to regenerate RuBP.
This reaction is called "Carbon
This reaction requires
Energy in the form of ATP.
These 2 molecules are formed from the
breakdown of the product of Carbon Fixation.
During this reaction Carbon
Some variations on Photosynthesis