A DNA sequence is composed of four nitrogenous bases, that code for the a specific order of amino acids in a protein. Each strand of the DNA double helix is composed of long sequences of the four bases, Adenine (A), Guanine (G), Cystosine (C) and Thymine (T). The Watson-Crick base pairing rule governs that the bases match up in a specific order; C-G and A-T.
DNA sequencing is the operation of determining the precise order of nucleotides (DNA bases) in a given DNA double helix strand.
- Alberts et al. Molecular Biology of the Cell (2008) 5th edition, Garland Science