Electropherogram printout from automated sequencer showing part of a DNA sequence

A DNA sequence or genetic sequence is a succession of letters representing the primary structure of a real or hypothetical DNA molecule or strand, with the capacity to carry information. In Biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms (including Deoxyribonucleic acid ( DNA) is a Nucleic acid that contains the genetic instructions used in the development and functioning of all known In Chemistry, a molecule is defined as a sufficiently stable electrically neutral group of at least two Atoms in a definite arrangement held together by Information as a concept has a diversity of meanings from everyday usage to technical settings

The possible letters are A, C, G, and T, representing the four nucleotide subunits of a DNA strand - adenine, cytosine, guanine, thymine bases covalently linked to phospho-backbone. Nucleotides are Organic compounds that consist of three joined structures a nitrogenous base a Sugar, and a Phosphate group Adenine is a Purine with a variety of roles in Biochemistry including Cellular respiration, in the form of both the energy-rich Adenosine Cytosine is one of the five main bases found in DNA and RNA. It is a Pyrimidine derivative with a Heterocyclic Aromatic ring Guanine is one of the five main Nucleobases found in the Nucleic acids DNA and RNA, the others being Adenine, Cytosine, Thymine is one of the four bases in the Nucleic acid of DNA that make up the letters ATGC 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 coding or noncoding. The genetic code is the set of rules by which information encoded in genetic material ( DNA or RNA sequences is translated into Proteins In Genetics, non-coding DNA describes DNA which does not contain instructions for making Proteins (or other cell products such as Noncoding DNA sequences can also contain "junk DNA. In Molecular biology, junk DNA is a provisional label for the portions of the DNA sequence of a Chromosome or a Genome for which no "

Sequences can be derived from the biological raw material through a process called DNA sequencing. The term DNA sequencing encompasses biochemical methods for determining the order of the Nucleotide bases Adenine, Guanine, Cytosine

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 (IUPAC) 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)     

See also

• DNA
• DNA sequencing
• DNA motif
• Single nucleotide polymorphism (SNP)

External links

• A bibliograph on features, patterns, correlations in DNA and protein texts