出典:Wikipedia
出典:『Wikipedia』 (2011/04/10 23:15 UTC 版)
A ribonucleotide or ribotide is a nucleotide in which a purine or pyrimidine base is linked to a ribose molecule. The base may be adenine (A), guanine (G), cytosine (C), or uracil (U). Note that thymine (T), which is found in deoxyribonucleotides, is not found as a ribonucleotide in living beings. Ribonucleotides have one, two, or three phosphate groups attached to the ribose sugar.