bases nucleosides nucleotides

Bases (nucleobases) are heterocyclic purine and pyrimidine analogues found in DNA and RNA.

Nucleosides comprise the RNA bases bound to a ribose sugar molecule -- examples are cytidine, uridine, adenosine, guanosine, thymidine and inosine. Deoxyribonucleosides comprise bases bound to a molecule of the sugar deoxyribose.

Nucleotides are nucleosides attached to a phosphate (phosphorylated by specific kinases), and deoxynucleotides are phosphorylated deoxyribonucleosides.

• adenine • AMP • ATP • cAMP • cytosine • C to T • C to U • guanine • thymidine • T U mismatch • uracil

purine pyrimidine

Adenine and guanine are purines and cytosine, uracil, and thymine are pyrimidines.



Left - purine (smaller molecule with bigger name) and (right) pyrimidine (larger molecule with smaller name)

grey - carbon / white - hydrogen / blue - nitrogen