What is a nucleotide?

What is a nucleotide?

• A. A base + sugar + 3 phosphates
• B. A base + sugar
• C. A sugar + 2 phosphates
• D. A base + sugar + 1 phosphate

Answer: (D)

Nucleotides are the building blocks of nucleic acids, made up of a nitrogenous base, a five-carbon sugar, and a single phosphate group. The combination of base + sugar + one phosphate is the correct representation of a nucleotide monomer that forms DNA and RNA backbones. The other options describe either missing a component (no phosphate or no base) or adding extra phosphates. A base + sugar + two or three phosphates would be a nucleotide with extra phosphates (like a nucleotide triphosphate), which are used during energy transfer and DNA synthesis, not the standard monomer that composes the polymer. In DNA the sugar is deoxyribose, while in RNA it’s ribose, but the essential structure remains base + sugar + one phosphate.

Nucleotides are the building blocks of nucleic acids, made up of a nitrogenous base, a five-carbon sugar, and a single phosphate group. The combination of base + sugar + one phosphate is the correct representation of a nucleotide monomer that forms DNA and RNA backbones. The other options describe either missing a component (no phosphate or no base) or adding extra phosphates. A base + sugar + two or three phosphates would be a nucleotide with extra phosphates (like a nucleotide triphosphate), which are used during energy transfer and DNA synthesis, not the standard monomer that composes the polymer. In DNA the sugar is deoxyribose, while in RNA it’s ribose, but the essential structure remains base + sugar + one phosphate.