cytosine

All Sources -
Updated Media sources (1) About encyclopedia.com content Print Topic Share Topic
views updated

cytosine (sī´tōsēn´), organic base of the pyrimidine family. It was isolated from the nucleic acid of calf thymus tissue in 1894. A suggested structure for cytosine, published in 1903, was confirmed in the same year when that base was synthesized in the laboratory. Combined with the sugar ribose in glycosidic linkage, cytosine forms a derivative called cytidine (a nucleoside), which in turn can be phosphorylated with from one to three phosphoric acid groups, yielding the three nucleotides CMP (cytidine monophosphate), CDP (cytidine diphosphate), and CTP (cytidine triphosphate). Analogous nucleosides and nucleotides are formed from cytosine and deoxyribose. The nucleoside derivatives of cytosine perform important functions in cellular metabolism. CTP acts as a coenzyme in both carbohydrate and lipid metabolism; it can readily donate one of its phosphate groups to adenosine diphosphate (ADP) to form adenosine triphosphate (ATP), an extremely important intermediate in the transfer of chemical energy in living systems. CTP is the source of the cytidine found in ribonucleic acid (RNA) and deoxycytidine triphosphate (dCTP) is the source of the deoxycytidine in deoxyribonucleic acid (DNA). Thus cytosine is intimately involved in the preservation and transfer of genetic information.

views updated

cytosine A pyrimidine derivative. It is one of the principal component bases of nucleotides and the nucleic acids DNA and RNA.

views updated

cytosine One of the pyrimidine bases of nucleic acids.

views updated

cytosine A pyrimidine base that occurs in both DNA and RNA.

views updated

cytosine A pyrimidine base found in nucleic acids. See also adenine, guanine, and thymine.

views updated

cytosine A pyrimidine base that occurs in both DNA and RNA.

views updated

cytosine (sy-toh-seen) n. one of the nitrogen-containing bases (see pyrimidine) that occurs in the nucleic acids DNA and RNA.