Dark reaction – Photosynthesis
- Also, known as the C3 cycle as the 1st stable compound produced is a 3C compound Phosphoglyceric acid (PGA).
- Occurs in the chloroplast of mesophyll cells.
- Initial acceptor of CO2 is a 5C compound Ribulose bisphosphate (RuBP).
- Carboxylation occurs with the help of Rubisco enzyme.
6RuBP + 6CO2 →12 3-PGA.
- Reduction: ATP & NADPH produced during light reaction are used to convert PGA to Glyceraldehyde-3-phosphate (G3P).
12 3-PGA + 12 ATP + 12NADPH → 12G3P + 12ADP + 12iP + 12NADP+.
- Formation of glucose: by using 2 molecules of G3P.
- Regeneration of 6RuBP: by using10 molecules of G3P & 6ATP
Photosynthesis is a process by which chlorophyll-containing cells synthesize carbohydrate from carbon dioxide & water with the help of solar energy & the byproduct is oxygen. It occurs in the Chloroplast. During the light reaction, light energy is converted into chemical energy in the form of ATP & NADPH. This ATP & NADPH is used in the dark reaction to fix CO2 in the stroma. Photophosphorylation occurs in the thylakoids (grana) & involves Photosystem I & II. A Photosystem is a group of closely associated pigments molecules that help in converting solar energy into chemical energy. Also referred as Light-harvesting complexes. It is of 2 types, Non- Cyclic & Cyclic.