Editing Nucleic acid sequence (section)

== Sequence determination ==
[[Image:DNA sequence.svg|right|thumb|268px|[[Electropherogram]] printout from automated sequencer for determining part of a DNA sequence]]

{{Main|DNA sequencing}}

DNA sequencing is the process of determining the [[nucleotide]] sequence of a given [[DNA]] fragment. The sequence of the DNA of a living thing encodes the necessary information for that living thing to survive and reproduce. Therefore, determining the sequence is useful in fundamental research into why and how organisms live, as well as in applied subjects. Because of the importance of DNA to living things, knowledge of a DNA sequence may be useful in practically any biological [[research]]. For example, in [[medicine]] it can be used to identify, [[diagnosis|diagnose]] and potentially develop [[therapy|treatments]] for [[genetic disease]]s. Similarly, research into [[pathogens]] may lead to treatments for contagious diseases. [[Biotechnology]] is a burgeoning discipline, with the potential for many useful products and services.

RNA is not sequenced directly. Instead, it is copied to a DNA by [[reverse transcriptase]], and this DNA is then sequenced.

Current sequencing methods rely on the discriminatory ability of DNA polymerases, and therefore can only distinguish four bases. An inosine (created from adenosine during [[RNA editing]]) is read as a G, and 5-methyl-cytosine (created from cytosine by [[DNA methylation]]) is read as a C. With current technology, it is difficult to sequence small amounts of DNA, as the signal is too weak to measure. This is overcome by [[polymerase chain reaction]] (PCR) amplification.

=== Digital representation ===
[[File:AMY1gene.png|thumb|370px|Genetic sequence in digital format.]]
Once a nucleic acid sequence has been obtained from an organism, it is stored ''[[in silico]]'' in digital format. Digital genetic sequences may be stored in [[sequence database]]s, be analyzed (see ''Sequence analysis'' below), be digitally altered and be used as templates for creating new actual DNA using [[artificial gene synthesis]].