Question

In Glycolysis at the point after NAD+ being reduced and prior to ADP being phosphorylated, where do the 2 inorganic phosphates (Pi) come from?

Answer 1

It appears are you discussing the 6th step of glycolysis. I think the inorganic phosphates come from the breakdown of H2PO4

Answer 2

in step 6, the inorganic phosphate, \[HPO _{4}^{2-}\] comes from the cytosolic pool of Pi. The Pi concentration in the cytosol is relatively high... ; the reaction is a phoshorolysis.

Answer 3

"The source of the phosphates is the pool of inorganic phosphates ions that are always present in the cytosol." (Biology, Campbell and Reece, pg.167)