I've been studying a fair bit of biosynthesis recently and notice that all kinds of things get phosphorylated before catabolic reactions occur. I can see that phosphorylating makes hydroxy groups better leaving groups, but I also see that various molecules get phosphorylated before different reactions occur in other positions of the molecule. An obvious one is how linear monosaccharides get phosphorylated on both ends, then suddenly they can just split in two. But its everywhere, shikimic acid gets phosphorylated at the 3-hydroxy group, then the 6-hydroxy group suddenly becomes much more reactive. What exactly does it do to the electron distribution to the molecule to alter reactivity so greatly? I've already heard of ATP being a high energy molecule and I hear the first stage of photosynthesis is all about generating high energy molecules but I don't know why this is. Also, what about molecules like DMAPP which have two phosphate groups attached?