Nucleosides
The combination of a base and a sugar is called a nucleoside. Two examples are shown below.
| guanine + ribose = |
cytosine + deoxyribose = |
 |
|
Nucleotides
Nucleotides are comprised of three portions, a base, a sugar, and a phosphate. Addition of a phosphate group at the 5' (or 3') position of the sugar turns the nucleoside into a nucelotide. A familiar example, adenosine monophosphate or AMP, is shown below
adenine + ribose + phosphate = adenosine 5'-monophosphate (AMP)
