base

One of the components of nucleosides, nucleotides and nucleic acids . Four different bases are found in naturally occurring DNA - the purines A (adenine ) and G (guanine ); and the pyrimidines C (cytosine ) and T (thymine, the common name for 5-methyluracil). In RNA, T is replaced by U (uracil). See: base pair.

One of the molecules that form DNA and RNA molecules. See also: nucleotide, base pair, base sequence

A substance that has a pH value between 7 and 14.

In the numeration system commonly used in scientific notation, the real number that is raised to a power denoted by the exponent and then multiplied by the coefficient to determine the value of the number represented without the use of exponents. Note: An example of a base is the number 6.25 in the expression 2.70 × 6.25^1.5 42.19. The 2.70 is the coefficient and the 1.5 is the exponent. In the decimal numeration system, the base is 10 and in the binary numeration system, the base is 2. The value e 2.718 is the natural base. 2. A reference value. 3. A number that is multiplied by itself as many times as indicated by an exponent.