Purine biosynthesis is the process by which cells create purine nucleotides, essential building blocks for DNA and RNA. This pathway involves a series of enzymatic reactions that convert simple molecules like amino acids, carbon dioxide, and formate into purine bases, primarily adenine and guanine. The biosynthesis occurs in two main pathways: the de novo pathway, which synthesizes purines from scratch, and the salvage pathway, which recycles purines from degraded nucleotides. Key enzymes, such as glutamine-PRPP amidotransferase, play crucial roles in regulating these pathways, ensuring a balanced supply of purines for cellular functions.