Nucleotide

A subunit of DNA or RNA. To form a DNA or RNA molecule, thousands of nucleotides are joined in a long chain. Each nucleotide is divided into three parts (with apologies to Caesar): {{}}A nitrogenous base (A, G, T, or C in DNA; A, G, U, or C in RNA), A phosphate molecule, and A sugar molecule (deoxyribose in DNA and ribose in RNA). A DNA oligonucleotide is a short piece of DNA composed of relatively few (oligo-) nucleotide bases.

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Originally a combination of a (nucleic acid) purine or pyrimidine, one sugar (usually ribose or deoxyribose), and a phosphoric group; by extension, any compound containing a heterocyclic compound bound to a phosphorylated sugar by an N-glycosyl link ( e.g., adenosine monophosphate, NAD⁺). For individual nucleotides see specific names. SYN: mononucleotide.

- cyclic n. a nucleoside monophosphate in which the phosphoryl group is linked twice to the sugar moiety; e.g., adenosine 3′,5′-cyclic monophosphate (cAMP).

- flavin n. flavin.

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nu·cle·o·tide 'n(y)ü-klē-ə-.tīd n any of several compounds that consist of a ribose or deoxyribose sugar joined to a purine or pyrimidine base and to a phosphate group and that are the basic structural units of RNA and DNA compare NUCLEOSIDE

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n.

a compound consisting of a nitrogen-containing base (a purine or pyrimidine) linked to a sugar and a phosphate group. Nucleic acids (DNA and RNA) are long chains of linked nucleotides (polynucleotide chains), which in DNA contain the purine bases adenine and guanine and the pyrimidines thymine and cytosine; in RNA, thymine is replaced by uracil.

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nu·cleo·tide (nooґkle-o-tīd) a phosphate ester of a nucleoside, particularly the 5′-phosphate of a pyrimidine or purine in N-glycosidic linkage with ribose or deoxyribose, as occurs in nucleic acid.