DNA sequence



A DNA sequence or genetic sequence is a succession of letters representing the of a real or hypothetical   or strand, with the capacity to carry.

The possible letters are A, C, G, and T, representing the four subunits of a DNA strand -, , ,  bases covalently linked to phospho-backbone. In the typical case, the sequences are printed abutting one another without gaps, as in the sequence AAAGTCTGAC, going from 5' to 3' from left to right. A succession of any number of nucleotides greater than four is liable to be called a sequence. With regard to its biological function, which may depend on context, a sequence may be sense or anti-sense, and either or. DNA sequences can also contain "."

Sequences can be derived from the biological raw material through a process called.

In some special cases, letters besides A, T, C, and G are present in a sequence. These letters represent ambiguity. Of all the molecules sampled, there is more than one kind of nucleotide at that position. The rules of the International Union of Pure and Applied Chemistry are as follows:

A = adenine C = cytosine G = guanine T = thymine R = G A (purine) Y = T C (pyrimidine) K = G T (keto) M = A C (amino) S = G C (strong bonds) W = A T (weak bonds) B = G T C (all but A)       D = G A T (all but C)        H = A C T (all but G)        V = G C A (all but T)        N = A G C T (any)