Objectives
Explain the light independent
reactions.
Outcomes
7: Explain how carbon dioxide is
absorbed by plants and incorporated
into organic molecules.
5: Describe the roles of reduced
NADP and ATP in the light
independent reactions.
3: Describe what the Calvin cycle is.
Key terms: Glycerate-3-phosphate, Ribulose, bisphosphate, Triose, phosphate
Light-independent stage
• Carbon dioxide is converted to carbohydrate
• Occurs in the stroma of the chloroplast
Task
Outcomes
Working in groups outline the
reactions involved in the light
independent stage of
photosynthesis.
7: Explain how carbon dioxide is
absorbed by plants and incorporated
into organic molecules.
5: Describe the roles of reduced
NADP and ATP in the light
independent reactions.
3: Describe what the Calvin cycle is.
Key terms: Glycerate-3-phosphate, Ribulose, bisphosphate, Triose, phosphate
Melvin Calvin
• Member of the Radiation
Laboratory at Berkeley,
University of California
• Studied using radioactively
labelled carbon dioxide
• 14CO2 fed to Chlorella algae
and its path tracked
Three phases
1. Carboxylation
Carbon dioxide fixation with ribulose bisphosphate
(RuBP)
2. Reduction
Reduction of glycerate 3-phosphate (GP) to
glyceraldehyde 3-phosphate (GALP)
3. Regeneration
Re-formation of the CO2
acceptor molecules
Phase 1: Carboxylation
Rubisco
CO2
GP
6C
molecule
RuBP
GP
RUBISCO
Phase 2: Reduction
2ATP
2ADP + 2Pi
GP
GALP
GP
GALP
2NADPH + H+
2NADP+
Phase 3: Regeneration
ATP
ADP + Pi
GALP
RuBP
GALP
Synthesis of Organic Substances
GALP
GALP
hexose
GALP
GP
glycerol
fatty
acids
lipids
GALP
amino
acids
CO2
Glucose
C6H12O6
6C
Ribulose
bisphosphate
(RuBP)
5C
6C Molecule yet to
be isolated
unstable
3C
2 x Glyceraldehyde
3 phospate
(2 GALP)
NADP
Reduced
NADP
3C
2 x Glycerate 3
phosphate (2GP)
ADP + P
ATP
Match structure and function
Double membrane
chloroplast envelope
As much light as possible can
be absorbed
Thylkakoids have large
surface area
Needed for the lightdependent reaction to take
place
ATP synthase molecules
in thylakoid membrane
Reactants kept close to
reaction sites
Stroma contains
enzymes, sugars and
organic acids
Produce ATP in the lightdependent reaction
Questions
What are the roles of GP, GALP,
RuBP, RUBISCO?
What are the uses of glucose?
Where are the products from the
light dependent stage used?
Outcomes
7: Explain how carbon dioxide is
absorbed by plants and incorporated
into organic molecules.
5: Describe the roles of reduced
NADP and ATP in the light
independent reactions.
3: Describe what the Calvin cycle is.
Key terms: Glycerate-3-phosphate, Ribulose, bisphosphate, Triose, phosphate
Task
Using a sheet of A3 paper outline
the reactions which take place
during photosynthesis, including
both the light dependent and light
independent reactions.
Outcomes
7: Explain how carbon dioxide is
absorbed by plants and incorporated
into organic molecules.
5: Describe the roles of reduced
NADP and ATP in the light
independent reactions.
3: Describe what the Calvin cycle is.
Key terms: Glycerate-3-phosphate, Ribulose, bisphosphate, Triose, phosphate