Orotate next reacts with PRPP to yield OMP. This reaction occurs with the loss of a high-energy bond and is exergonic. Moreover, the formation and subsequent hydrolysis of PP, further promote product formation. OMP, a pyrimidine nucleotide undergoes a decarboxylation-yielding uridine 5'- monophosphate (UMP). This decarboxylation reaction is accompanied by a decrease in free energy that drives this unidirectional reaction (PRINCIPLE 6 OF BIOENERGETICs).