This question is related to something that happens when 3-phosphoglyceraldehyde is converted to 1,3-bisphosphoglycerate during glycolysis.
As I understand it, 3-phosphoglyceraldehyde is deprotonated by NAD+ and phosphorylated by a Pi group, which results in NADH + H. The extra H apparently comes from the Pi group (which I believe is called orthophosphate ).
Now, where does the Pi come from? is it just sitting in the cytosol?, does all Pi have a hydrogen? can someone clarify what an orthophosphate is, I never heard of that term.