Polynucleotides

Polynucleotides are polymers made of nucleotide monomers linked by phosphodiester bonds, forming a sugar-phosphate backbone with a nitrogenous base on each sugar. Chains run in a defined 5' to 3' direction and vary in length.

Each nucleotide comprises a five-carbon sugar (deoxyribose or ribose), a phosphate group, and a nitrogenous base (A, G, C, T in DNA; A, G, C, U in RNA).

DNA and RNA are the principal polynucleotides. DNA is typically double-stranded and encodes genetic information through base pairing (A with T, G with C). RNA is usually single-stranded and participates in transcription, translation, and regulation, often forming complex structures via intramolecular base pairing (A–U, G–C).

Biologically, polynucleotides are synthesized by polymerases in the 5' to 3' direction, using a template. DNA replication copies the genome; transcription produces RNA; translation uses RNA sequences to guide protein synthesis.

In biotechnology, synthetic polynucleotides (oligonucleotides) serve as primers, probes, antisense agents, or therapeutic tools. They are customizable in sequence and chemistry to suit various research and clinical applications.