The three parts of a nucleotide are:
- A nitrogenous base
- A pentose (five-carbon) sugar
- A phosphate group
The nitrogenous base contains genetic information and can be one of adenine, cytosine, guanine, thymine (in DNA), or uracil (in RNA). The pentose sugar is deoxyribose in DNA and ribose in RNA. The phosphate group links nucleotides together forming the backbone of DNA or RNA.