Discovery and Overview of Calvin Cycle
Historical context of Melvin Calvin's work using radioactive 14C and the general outline of the C3 pathway.
What is Discovery and Overview of Calvin Cycle?
A series of biochemical reactions in photosynthesis where the enzyme RuBisCO captures atmospheric carbon dioxide and uses it to help build an energy-rich sugar molecule (like glucose).
Key points
- Explain the historical discovery of the Calvin cycle.
- Identify the location of the Calvin cycle within the chloroplast.
- Describe the overall purpose of the Calvin cycle in photosynthesis.
- List the main stages of the Calvin cycle.
Common exam trap
Confusing the Calvin cycle with the light-dependent reactions.
Definitions
- Term
Calvin Cycle
- Meaning
A series of biochemical reactions in photosynthesis where the enzyme RuBisCO captures atmospheric carbon dioxide and uses it to help build an energy-rich sugar molecule (like glucose).
- Term
C3 Pathway
- Meaning
An alternative name for the Calvin cycle, referring to the fact that the first stable organic product of carbon fixation is a three-carbon compound called 3-phosphoglycerate.
- Term
RuBisCO
- Meaning
Ribulose-1,5-bisphosphate carboxylase/oxygenase, the enzyme that catalyzes the first step of carbon fixation in the Calvin cycle.
- Term
RuBP
- Meaning
Ribulose-1,5-bisphosphate, a five-carbon sugar that acts as the primary carbon dioxide acceptor in the Calvin cycle.
- Term
3-PGA
- Meaning
3-phosphoglycerate, a three-carbon molecule formed when CO₂ is fixed to RuBP in the Calvin cycle.
- Term
G3P
- Meaning
Glyceraldehyde-3-phosphate, a three-carbon sugar phosphate that is the direct product of the Calvin cycle, used to synthesize glucose and regenerate RuBP.
Learning objectives
Explain the historical discovery of the Calvin cycle.
Identify the location of the Calvin cycle within the chloroplast.
Describe the overall purpose of the Calvin cycle in photosynthesis.
List the main stages of the Calvin cycle.
Recognize the inputs (CO₂, ATP, NADPH) and outputs (glucose precursors) of the cycle.
Prerequisites
Photosynthesis: Basic understanding of the overall process.
Chloroplast structure and function.
Light-dependent reactions: Products (ATP, NADPH).
Enzymes: Role and specificity.
Common mistakes
Confusing the Calvin cycle with the light-dependent reactions.
Forgetting that it occurs in the stroma, not the thylakoids.
Misunderstanding the role of ATP and NADPH.
Not recognizing RuBP as the CO₂ acceptor.
Assuming it directly uses light energy.
Keywords
Calvin Cycle
C3 Pathway
Photosynthesis
Light-independent reactions
Carbon fixation
RuBisCO
RuBP
3-PGA
G3P
Stroma
Melvin Calvin
ATP
NADPH
Practice preview
Which of the following is NOT a stage of the Calvin cycle?…
medium
What radioactive isotope was primarily used by Melvin Calvin to study the pathway of carbon in photosynthesis?…
easy
The Calvin cycle is also known as the:…
easy