Basepairings

Basepairings refers to the specific hydrogen-bonded interactions between nucleotide bases that underpin the structure and function of nucleic acids. In DNA, the canonical Watson–Crick pairs are adenine with thymine (A–T) and guanine with cytosine (G–C). A–T pairs are stabilized by two hydrogen bonds, while G–C pairs are stabilized by three, making GC-rich regions more thermally stable. In RNA, thymine is replaced by uracil, so adenine pairs with uracil (A–U), and G–C pairing remains common. RNA can also form noncanonical pairings, such as G–U wobble pairs, which contribute to codon recognition and RNA structural diversity.

DNA generally exists as two antiparallel, complementary strands, so the sequence on one strand determines its partner. This complementary base pairing is essential for replication, transcription, and repair, guiding polymerases to add nucleotides that match the template. It also underlies hybridization-based techniques and primer design used in PCR, sequencing, and various diagnostic assays.

Base pairing also governs RNA structure and function. Intramolecular base pairing shapes rRNA, tRNA, and mRNA conformations, while intermolecular base pairing between tRNA anticodons and mRNA codons drives accurate translation. Noncanonical pairings and structural motifs expand the functional repertoire of RNA molecules.

Overall, basepairings provide the molecular basis for genetic information storage, its faithful transmission, and the dynamic folding and interactions of nucleic acids in biology.