Base pair

Definition

The fundamental unit of double-stranded nucleic acids, consisting of two complementary nucleobases (adenine–thymine or cytosine–guanine in DNA; adenine–uracil or cytosine–guanine in RNA) linked by hydrogen bonds. Base pairs constitute the structural and informational foundation of DNA and RNA, enabling genetic storage, replication, transcription, and molecular recognition. In arthropod biology, base-pair variation underlies molecular phylogenetics, population structure analysis, and studies of adaptation at the genomic level.

Etymology

From 'base' (chemical base/nucleobase) + 'pair' (two complementary units), reflecting the paired hydrogen-bonded structure.

Example

Comparing mitochondrial COI gene sequences across 658 base pairs is a standard DNA barcoding approach for identifying cryptic species of parasitoid wasps.

Synonyms

• bp (abbreviation)
• nucleotide pair

Related Terms

• Nucleotide
• DNA barcoding
• Genome
• mitochondrial DNA
• molecular phylogenetics
• single nucleotide polymorphism
• Watson-Crick pairing

Usage Notes

Abbreviated 'bp' in scientific literature; 'kbp' or 'kb' for kilobase pairs, 'Mbp' for megabase pairs. In arthropod genomics, base-pair counts vary enormously: the tiny parasitoid wasp Megaphragma mymaripenne has one of the smallest insect genomes at ~15.5 million base pairs, while the mountain grasshopper Podisma pedestris exceeds 16 billion base pairs. Distinct from 'base' alone, which refers to a single nucleobase.