| conjugate acid-base pair | In prototonic solvents (e.g., H2O, NH3, acetic acid), two molecular species differing only in the presence or absence of a hydrogen ion (e.g., carbonic acid/bicarbonate ion or ammonium ion/ammonia); the basis of buffer action. (05 Mar 2000) |
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| nucleotide pair | <molecular biology> Two nitrogenous bases (adenine and thymine or guanine and cytosine) held together by weak bonds. Two strands of DNA are held together in the shape of a double helix by the bonds between base pairs. (09 Oct 1997) |