Nucleoside vs Nucleotide A nucleotide (right) consists of a nucleoside (left) and 1-3 phosphate groups (the depiction below contains one phosphate): <img src=http://ihub.concedere.net/nucleoside.GIF><img src=http://ihub.concedere.net/nucleotide.gif> The base in a nucleoside consists of a purine (left) or a pyrimidine (right): <img src=http://ihub.concedere.net/purines.gif><img src=http://ihub.concedere.net/pyrimidines.gif> Source: <A HREF="http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nucleotides.html" target="_blank">http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/N/Nucleotides.html</A>