What are the three parts of a nucleotide?

• A. 5 carbon sugar; phosphate group; nitrogenous base
• B. 3 carbon sugar; phosphate group; amino acid
• C. 5 carbon sugar; lipid tail; nitrogenous base
• D. Phosphate group; water; ribose

Answer: (A)

Nucleotides are built from three parts: a five‑carbon sugar, a phosphate group, and a nitrogenous base. The sugar is a pentose (deoxyribose in DNA or ribose in RNA). The phosphate group links sugars together to form the sugar–phosphate backbone of nucleic acids, while the nitrogenous base provides the genetic information through its sequence. Among the options, the one that lists a five‑carbon sugar, a phosphate group, and a nitrogenous base matches exactly what a nucleotide is. The other choices include components from other biomolecules (such as amino acids or lipid tails) or incorrect descriptions of the sugar (like a three‑carbon sugar) or other non-part components (like water), which do not belong to nucleotides.