Pyrimidine biosynthesis is the process by which cells produce pyrimidine nucleotides, essential components of DNA and RNA. This pathway begins with the formation of carbamoyl phosphate from glutamine and bicarbonate, which then combines with aspartate to form dihydroorotate. The next steps involve the conversion of dihydroorotate to orotate, followed by the addition of a ribose sugar to form uridine monophosphate (UMP). UMP can then be phosphorylated to produce other pyrimidine nucleotides, such as cytidine triphosphate (CTP) and thymidine triphosphate (TTP), which are vital for nucleic acid synthesis and cellular function.