Based on the information provided, molecule X is likely a nucleotide. Nucleotides are the building blocks of nucleic acids, such as DNA and RNA. They consist of a sugar molecule (either deoxyribose in DNA or ribose in RNA) and a phosphate group, along with a nitrogenous base. The sugar and phosphate group form the backbone of the nucleic acid molecule, while the nitrogenous base determines its specific genetic code.