Calvin Cycle

Formula for Photosynthesis

6H₂O + 6CO₂ + Light Energy → C₆H₁₂O₆+ 6O₂

Light Reactions

reactions of photosynthesis that use energy from light to produce ATP and NADPH

Carbon Fixation

The initial incorporation of carbon from CO2 into an organic compound by an autotrophic organism, mainly via NADPH and ATP.

Synthesis

the process of producing a chemical compound (usually by the union of simpler chemical compounds)

State of CO₂

Fully Oxidized, very little chemical energy.

State of C₆H₁₂O₆

Highly Reduced, lots of chemical energy.

Synthesis and Endergonic Processes…

Input of energy into reaction.

The Reduction of CO₂ → C₆H₁₂O₆

Proceeds with many small uphill steps.
Uses energy in ATP and NADPH

Exergonic

chemical reaction that releases some form of energy, such as light or heat.

Endergonic

energy has to be put into the reaction (phosphorylating something)

Stroma

The fluid of the chloroplast surrounding the thylakoid membrane; involved in the synthesis of organic molecules from carbon dioxide and water.

Products of the Light reactions…

ATP, NADPH, O₂

RuBisCo

Ribulose bisphosphate carboxylase, the enzyme that catalyzes the first step of the Calvin cycle.

Stages of the Calvin Cycle

1. Carbon Fixation
2. Reduction
3. Regeneration of RuBP

RuBP

ribulose biphosphate; a five-carbon carbohydrate that combines with CO2 to form two molecules of PGA in the first step of the Calvin Cylce

G3P (PGAL)

a 3 carbon sugar; for each CO2 are formed in the Calvin cycle; 1 leaves to be used in the cell, 5 are use for regeneration of RuBP

2 of these react to make glucose…

G3P (PGAL)

Glyceraldehyde-3-Phosphate (G3P)

End Product of the Calvin Cycle and is an important intermediate, from which the main macro-molecules can be formed: amino acids, nucleic acids, lipids, and carbohydrates.

Rubisco

Enzyme responsible for CO2 fixation. It combines ribulose bisphosphate with CO2 to from an unstable 6 carbon molecule. This is the first step in the Calvin cycle. It is the most abundant enzyme in the world.

The Reactants of the Calvin Cycle:

6CO₂ from the air
18 ATP provide power (from light reactions)
12 NADPH provide power and H (from light reactions)

Formula for the Calvin Cycle:

CO₂ + ATP + NADPH → C₆H₁₂O₆ + ADP + NADP⁺

Formula for the Light Reactions:

H₂O + Light Energy → O₂ + ATP + NADPH

Summary of the Light Reactions:

Produces ATP
Produces NADPH
Releases O₂ as a waste product.

Summary of the Calvin Cycle:

Builds Sugars
Uses ATP & NADPH
Recycles ADP & NADP⁺
(Atoms are rearranged)