A nucleotide was an organic molecule present in DNA.

Vorta have a couple of specific nucleotide sequences that have only found in their DNA. (SCE novel: Malefictorum)

When Julian Bashir studied a Jem'Hadar boy, a nucleotide analysis revealed that the boy's DNA had been altered. Bashir also used a nucleotide sequence on the Dominion's Quickening virus on a search for a cure. (DS9 episodes: "The Abandoned", "The Quickening")