Nucleotide biosynthesis is the process by which cells create nucleotides, the building blocks of DNA and RNA. This process involves two main pathways: the de novo pathway, which synthesizes nucleotides from simple molecules, and the salvage pathway, which recycles existing nucleotides. Both pathways are essential for cell growth and division. Nucleotides consist of a nitrogenous base, a sugar, and phosphate groups. The nitrogenous bases include adenine, cytosine, guanine, and thymine for DNA, and uracil replaces thymine in RNA. Proper nucleotide biosynthesis is crucial for maintaining genetic information and supporting cellular functions.