Explain why chloroplasts need to import inorganic phosphate (Pi) from the cytoplasm as an exchange of exporting glyceraldehyde-3-phosphate (GA3P). Use the following information:
(Ru1,5-BP is ribulose-1,5-bisphosphate. Similar to fructose-1,6-bisphosphate, Ru1,5-BP has TWO phosphate groups)
1. Net reaction of CBB cycle is: 3 Ru1,5-BP + 3 CO2 (carbon dioxide) => 3 Ru1,5-BP + GA3P
2. Each turn of CBB cycle (per 1 molecule of Ru1,5-BP) requires an input of 3 ATP and 2 NADPH. (sub question - which enzymes need these?)
3. CBB cycle needs to be coupled to ATP synthesis. Equation of ATP synthesis is: ADP + Pi => ATP + H2O
4. Do not worry about H2O and H+.