Question

What are the enzymes in the light-independent stage of photosynthesis for?

Answer 1

The light-dependent stage of photosynthesis involves the Calvin cycle which consists of 3 steps:
- Fixation of carbon dioxide by ribulose 1,5-bisphosphate to form 2 molecules of 3-phosphoglycerate.
This reaction is catalysed by ribulose 1,5-bisphosphate carboxylase/oxygenase also known as rubisco. This enzyme is found on the stromal surface of the thylakoid membranes of chloroplasts.
- The reduction of 3-phosphoglycerate to form hexose sugars: glucose 1-phosphate,glucose 6-phosphate, and fructose 6-phosphate.
This conversion is like that of the gluconeogenic pathway except that there is glyceraldehyde 3-phosphate dehydrogenase in chloroplast which is responsible for the generation of glyceraldehyde 3-phosphate and is specific for NADPH and not NADH.
- The regeneration of ribulose 1,5-bisphosphate so that more CO2 can be fixed.
Enzyme: Transketolase & Aldose