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NCI Dictionary of Cancer Terms


base pair  listen  (bays payr)

  Molecules called nucleotides, on opposite strands of the DNA double helix, that form chemical bonds with one another. These chemical bonds act like rungs in a ladder and help hold the two strands of DNA together. There are four nucleotides, or bases, in DNA: adenine (A), cytosine (C), guanine (G), and thymine (T). These bases form specific pairs (A with T, and G with C).

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DNA base pair; drawing shows double-stranded DNA with bonds between two pairs of  nitrogen-containing bases [adenine (A) and thymine (T), and cytosine (C) and guanine (G)].