Following the light reactions, the Calvin cycle is the second set of metabolic processes in photosynthesis.
The light reactions employ photons and water to produce NADPH, oxygen, and water.
The NADPH may then be utilized to fuel the Calvin cycle, which generates energy by using the energy stored in ATP and NADPH during light reactions.
The light reactions occur in the chloroplasts, whereas the Calvin cycle occurs in the stroma and is not light-dependent.
The Calvin cycle produces glyceraldehyde 3-phosphate (G3P), a three-carbon sugar, by using energy to bond reactant carbon dioxide.
G3P is subsequently utilized to synthesize sucrose, starch, and cellulose, which are ultimately employed for energy storage and metabolism.
RuBP enzyme:
RuBP, which stands for ribulose bisphosphate, is a 5-carbon molecule that is involved in the Calvin cycle, which is one of the photosynthesis's light-independent processes.
With the aid of an enzyme called RuBisCO, atmospheric carbon dioxide is coupled with RuBP to generate a 6 carbon molecule.
It can be detected in mesophyll cells.
The function of RuBP:
The major enzyme of the dark reaction, RUBP carboxylase, also catalyzes another reaction that interferes with the Calvin cycle's operation.
When the temperature and oxygen concentration rise, RUBP carboxylase has a higher affinity for oxygen than carbon dioxide.
As a result, in the presence of increased oxygen concentrations and high temperatures, RUBP works as an oxygenase, converting RUBP (ribulose 1,5 bisphosphate) to a 3-carbon product phosphoglyceric acid (PGA) and a 2-carbon compound phosphoglycolate.
Phosphatidylglycolate is rapidly transformed into glycolate or glycolic acid.