Monomer of Nucleic Acids: Nucleotides
The biochemistry behind purine and pyrimidine biosynthesis is quite complex. Purines are comstructed literally atom by atom from several distinct carbon and nitrogen sources, in cluding CO2 (Figure5.27a). The first key purine, inosinic acid (Figure5.27b). is the precursor of the purine nucleotides adenine and guanine (Figure 3.9). Once these are synthesized (in their triphosphate forms) and have been attached to their correct pentose sugar, they are ready to be incorporated into DNA or RNA.