Well, by adding the nucleotide, we add these negative charges. And anytime we add negative charges onto a system, we make that system more reactive. Its energy increases and that makes it more reactive. And so we basically activate the sugar by adding that nucleotide component. And now we have an activated glucose nucleotide. And now we can use the glycosal transferase to basically catalyze the formation of the glycocitic bond between this carbon of the incoming glucose and a carbon on that sugar molecule.