The three parts of a nucleotide are:

• Nitrogenous base
• Five-carbon sugar (pentose)
• Phosphate group

Explanation:

• The nitrogenous base provides the information-coding component and determines the identity of the nucleotide (adenine, thymine, cytosine, guanine, and in RNA, uracil). The base attaches to the sugar.
• The pentose sugar (deoxyribose in DNA, ribose in RNA) forms the backbone of the nucleotide and determines the molecule’s structural properties.
• The phosphate group links the sugar molecules together through phosphodiester bonds, creating the sugar–phosphate backbone that holds nucleotides in sequence.