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nucleotide

noun

The basic building block of nucleic acids, such as DNA and RNA. It is an organic compound made up of nitrogenous base, a sugar, and a phosphate group.

DNA molecule consists of nucleotides in which the sugar component is deoxyribose whereas the RNA molecule has nucleotides in which the sugar is a ribose. The most common nucleotides are divided into purines and pyrimidines based on the structure of the nitrogenous base. In DNA, the purine bases include adenine and guanine while the pyrimidine bases are thymine and cytosine. RNA includes adenine, guanine, cytosine, and uracil in stead of thymine (thymine is produced by adding a methyl to uracil).

Aside from serving as precursors of nucleic acids, nucleotides also serve as important cofactors in cellular signaling and metabolism. These cofactors include CoA, flavin adenine dinucleotide (FAD), flavin mononucleotide, adenosine triphosphate (ATP) and nicotinamide adenine dinucleotide phosphate (NADP).