The backbone components of polynucleotides are phosphates, pentose sugars and bases. The basic building block of nucleic acids is nucleotides. Nucleotide molecules are composed of three molecules linked together: bases, pentose sugars, and phosphates.

The backbone components of polynucleotides are

The basic building blocks of nucleic acids are nucleotides. Nucleotide molecules are composed of three molecules linked together: bases, pentose sugars, and phosphates. A molecule composed of several or a dozen nucleotides connected by phosphodiester bonds is called an oligonucleotide, and a polymer composed of more nucleotides connected is a polynucleotide.

In a polynucleotide chain, since the pentose sugars and phosphates that make up the nucleotide unit are the same, the difference between the nucleotides is actually only the bases they carry. Therefore, the pentose sugar and phosphate in the nucleic acid molecule together form its skeleton structure, but do not participate in the storage and expression of information.