The Light Independent Reactions

The Light Independent Reactions
 Also known as the Calvin Cycle
 Occurs in chloroplast stroma
 Energy to supply reactions comes from ATP and NADPH
formed in the light reaction
There are three major stages to the Calvin cycle:
1. Stage 1 - Carbon fixation
CO2 from the atmosphere reacts with ribulose biphosphate
RuBP) two 3C phosphoglycerate molecules (PGA) are
- catalyzed by RUBISCO (most abundant protein in nature)
2. Stage 2 - Reduction
PGA molecules are phosphorylated using ATP and then
reduced by NADPH to produce PGAL.
3. Stage 3 - Reformation of RuBP
Some of the PGAL is converted to glucose
(2 PGAL makes 1 glucose)
- plants may use glucose as a building block to make other
sugars, starch, fats, amino acids, nucleotides and other
Majority of PGAL is used to regenerate RuBP.
- PGAL is converted to ribulose phosphate which is
phosphorylated to form RuBP.
Summarize, in a chart, the following facts about the LIGHT
INDEPENDENT REACTIONS (a.k.a. the Calvin Cycle):
 Location of the Light Independent Reactions
 Number of carbon dioxide molecules required to produce one
glucose molecule
 Number of NADPH used to from one glucose molecule
 Number of ATP used to form one glucose molecule
 Source of ATP and NADPH for this series of reactions