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What is the building block of DNA consisting of a five-carbon sugar covalently bonded to a nitrogenous base and a phosphate group?

Nucleoside

Sugar

Phosphate

Nucleotide

This is describing a nucleotide. Each nucleotide in DNA has three parts: a five-carbon sugar (deoxyribose in DNA), a nitrogenous base, and a phosphate group. The sugar bonded to the base is the nucleoside, but once the phosphate is attached, it becomes a full nucleotide. The sugar alone or the phosphate alone are only parts of the structure, not the complete building block. Nucleotides link through phosphodiester bonds to form the DNA backbone, with the bases extending inward to pair with the complementary strand.