Editing DNA sequencing (section)

==== Single molecule real time (SMRT) sequencing ====
{{Main|Single-molecule real-time sequencing}}
SMRT sequencing is based on the sequencing by synthesis approach. The DNA is synthesized in zero-mode wave-guides (ZMWs)&nbsp;– small well-like containers with the capturing tools located at the bottom of the well. The sequencing is performed with use of unmodified polymerase (attached to the ZMW bottom) and fluorescently labelled nucleotides flowing freely in the solution. The wells are constructed in a way that only the fluorescence occurring by the bottom of the well is detected. The fluorescent label is detached from the nucleotide upon its incorporation into the DNA strand, leaving an unmodified DNA strand. According to [[Pacific Biosciences]] (PacBio), the SMRT technology developer, this methodology allows detection of nucleotide modifications (such as cytosine methylation). This happens through the observation of polymerase kinetics. This approach allows reads of 20,000 nucleotides or more, with average read lengths of 5 kilobases.<ref name="flxlexblog.wordpress.com"/><ref>{{cite web|url=http://www.genomeweb.com/sequencing/pacbio-sales-start-pick-company-delivers-product-enhancements|title=PacBio Sales Start to Pick Up as Company Delivers on Product Enhancements|date=12 February 2013}}</ref> In 2015, Pacific Biosciences announced the launch of a new sequencing instrument called the Sequel System, with 1 million ZMWs compared to 150,000 ZMWs in the PacBio RS II instrument.<ref>{{cite web|url=http://www.bio-itworld.com/2015/9/30/pacbio-announces-sequel-sequencing-system.aspx|title=Bio-IT World|website=bio-itworld.com|access-date=16 November 2015|archive-date=29 July 2020|archive-url=https://web.archive.org/web/20200729220749/http://www.bio-itworld.com/2015/9/30/pacbio-announces-sequel-sequencing-system.aspx|url-status=dead}}</ref><ref>{{cite web|url=https://www.genomeweb.com/business-news/pacbio-launches-higher-throughput-lower-cost-single-molecule-sequencing-system|title=PacBio Launches Higher-Throughput, Lower-Cost Single-Molecule Sequencing System|date=October 2015}}</ref> SMRT sequencing is referred to as "[[Third-generation sequencing|third-generation]]" or "long-read" sequencing.