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DNA sequence
 
 
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A DNA sequence or genetic sequence is a succession of letters representing the primary structure
Primary structure

In biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms ....
 of a real or hypothetical DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 or strand, with the capacity to carry information
Information

Information as a Conveyed concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control system, data, form, instruction, knowledge, Meaning , stimulation, pattern, perception, and knowledge representation....
 as described by the central dogma of molecular biology
Central dogma of molecular biology

The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970:In other words, 'once information gets into protein, it can't flow back to nucleic acid.'...
.

The possible letters are A, C, G, and T, representing the four nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
 bases
Nucleobase

Nucleobases are the parts of DNA and RNA that may be involved in pairing . The main ones are cytosine, guanine, adenine , thymine and uracil , abbreviated as C, G, A, T, and U, respectively....
 of a DNA strand — adenine
Adenine

Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactor s nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and Protein biosynthesis, as a chemical component of DNA and RNA....
, cytosine
Cytosine

Cytosine is one of the five main bases found in DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached ....
, guanine
Guanine

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine....
, thymine
Thymine

Thymine is one of the four bases in the nucleic acid of DNA that make up the letters GCAT. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine....
 — covalently linked to a phosphodiester
Phosphodiester bond

A phosphodiester bond is a group of strong covalent bond between the Phosphorus in a phosphate group and two other molecules over two ester bonds....
 backbone.






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Dna Sequence
A DNA sequence or genetic sequence is a succession of letters representing the primary structure
Primary structure

In biochemistry, the primary structure of a biological molecule is the exact specification of its atomic composition and the chemical bonds connecting those atoms ....
 of a real or hypothetical DNA
DNA

Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
 molecule
Molecule

In chemistry, a molecule is defined as a sufficiently stable, electric charge neutral group of at least two atoms in a definite arrangement held together by very strong chemical bonds....
 or strand, with the capacity to carry information
Information

Information as a Conveyed concept has a diversity of meanings, from everyday usage to technical settings. Generally speaking, the concept of information is closely related to notions of constraint, communication, control system, data, form, instruction, knowledge, Meaning , stimulation, pattern, perception, and knowledge representation....
 as described by the central dogma of molecular biology
Central dogma of molecular biology

The central dogma of molecular biology was first enunciated by Francis Crick in 1958 and re-stated in a Nature paper published in 1970:In other words, 'once information gets into protein, it can't flow back to nucleic acid.'...
.

The possible letters are A, C, G, and T, representing the four nucleotide
Nucleotide

Nucleotides are molecules that comprise the structural units of RNA and DNA. Additionally, nucleotides play central roles in metabolism. In that capacity, they serve as sources of chemical energy , participate in cell signaling , and are incorporated into important cofactors of enzymatic reactions ....
 bases
Nucleobase

Nucleobases are the parts of DNA and RNA that may be involved in pairing . The main ones are cytosine, guanine, adenine , thymine and uracil , abbreviated as C, G, A, T, and U, respectively....
 of a DNA strand — adenine
Adenine

Adenine is a nucleobase with a variety of roles in biochemistry including cellular respiration, in the form of both the energy-rich adenosine triphosphate and the cofactor s nicotinamide adenine dinucleotide and flavin adenine dinucleotide , and Protein biosynthesis, as a chemical component of DNA and RNA....
, cytosine
Cytosine

Cytosine is one of the five main bases found in DNA and RNA. It is a pyrimidine derivative, with a heterocyclic aromatic ring and two substituents attached ....
, guanine
Guanine

Guanine is one of the five main nucleobases found in the nucleic acids DNA and RNA, the others being adenine, cytosine, thymine, and uracil. In DNA, guanine is paired with cytosine....
, thymine
Thymine

Thymine is one of the four bases in the nucleic acid of DNA that make up the letters GCAT. The others are adenine, guanine, and cytosine. Thymine always pairs with adenine....
 — covalently linked to a phosphodiester
Phosphodiester bond

A phosphodiester bond is a group of strong covalent bond between the Phosphorus in a phosphate group and two other molecules over two ester bonds....
 backbone. In the typical case, the sequences are printed abutting one another without gaps, as in the sequence AAAGTCTGAC, read left to right in the 5' to 3'
Directionality (molecular biology)

Directionality, in molecular biology, refers to the end-to-end chemical orientation of a single strand of nucleic acid. The chemical convention of naming carbon atoms in the nucleotide Furanose numerically gives rise to a 5' end and a 3' end ....
 direction. Short sequences of nucleotides are referred to as oligonucleotides
Oligonucleotide

An oligonucleotide is a short nucleic acid polymer, typically with twenty or fewer nucleotide. Although they can be formed by bond cleavage of longer segments, they are now more commonly synthesized by polymerizing individual nucleotide precursors....
 and are used in a range of laboratory applications in molecular biology
Molecular biology

Molecular biology is the study of biology at a molecule level. The field overlaps with other areas of biology and chemistry, particularly genetics and biochemistry....
. With regard to biological function, a DNA sequence may be considered sense or antisense
Sense (molecular biology)

Sense, when applied in a molecular biology context, is a general concept used to compare the polarity of nucleic acid molecules, such as DNA or RNA, to other nucleic acid molecules....
, and either coding
Coding strand

When referring to Transcription , the coding strand is the DNA strand which has the same Nucleobase sequence as the RNA transcript produced ....
 or noncoding
Noncoding DNA

In genetics, non-coding DNA describes DNA which does not contain genetic code for making proteins . In eukaryotes, a large percentage of many organisms' total genome sizes is comprised of noncoding DNA ....
. DNA sequences can also contain "junk DNA
Junk DNA

In evolutionary biology and molecular biology, junk DNA is a provisional label for the portions of the DNA sequence of a chromosome or a genome for which no Function has been identified....
."

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

The term DNA sequencing refers to methods for determining the order of the nucleotide bases, adenine, guanine, cytosine, and thymine, in a molecule of DNA....
.

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

    Deoxyribonucleic acid is a nucleic acid that contains the genetics instructions used in the development and functioning of all known living organisms and some viruses....
  • DNA sequencing
    DNA sequencing

    The term DNA sequencing refers to methods for determining the order of the nucleotide bases, adenine, guanine, cytosine, and thymine, in a molecule of DNA....
  • DNA motif
  • Single nucleotide polymorphism (SNP)
    Single nucleotide polymorphism

    A single-nucleotide polymorphism is a DNA sequence variation occurring when a single nucleotide — adenine, thymine, cytosine, or guanine — in the genome differs between members of a species ....
  • Sequence analysis
    Sequence analysis

    The term "sequence analysis" in biology implies subjecting a DNA sequence or peptide sequence to sequence alignment, sequence databases, Repeated Sequences searches, or other bioinformatics methods on a computer....


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