base pairing rule definition biology
Base Pairing. The rules of base pairing (or nucleotide pairing) are: A with T: the purine adenine (A) always pairs with the pyrimidine thymine (T) C with G: the pyrimidine cytosine (C) always pairs with the purine guanine (G) ... [users.rcn.com/jkimball.ma.ultranet/BiologyPages/B/...]