What is Three Parts of Nucleotide ? Nucleotides are biological molecules that form the building blocks of nucleic acids (DNA and RNA) and serve to carry packets of energy within the cell (ATP). In the form of the nucleoside triphosphates (ATP, GTP, CTP and UTP), nucleotides play central roles in metabolism. In addition, nucleotides participate in cell signaling (cGMP and cAMP), and are incorporated into important cofactors of enzymatic reactions (e.g. coenzyme A, FAD, FMN, NAD, and NADP+). A nucleotide is composed of a nucleobase (nitrogenous base), a five-carbon sugar (either ribose or 2-deoxyribose), and one or more phosphate groups. Three parts of nucleotide image That are three parts of nucleotide, Nucleotides can be synthesized by a variety of means both in vitro and in vivo. There a 4 different nucleotides ATP,GTP (purines) TTP,CTP (pyrimidines) which differ in the chemical structure of the base. They are generally referred by a single letter A, G, T,C. UTP