Editing DNA sequencing (section)

== Sample preparation ==
The success of any DNA sequencing protocol relies upon the DNA or RNA sample extraction and preparation from the biological material of interest.
* A successful DNA extraction will yield a DNA sample with long, non-degraded strands. 
* A successful RNA extraction will yield a RNA sample that should be converted to complementary DNA (cDNA) using reverse transcriptase—a DNA polymerase that synthesizes a complementary DNA based on existing strands of RNA in a PCR-like manner.<ref>{{cite journal | vauthors = Harbers M | year = 2008 | title = The Current Status of cDNA Cloning | journal = Genomics | volume = 91 | issue = 3| pages = 232–42 | doi = 10.1016/j.ygeno.2007.11.004 | pmid = 18222633 | doi-access = free }}</ref> Complementary DNA can then be processed the same way as genomic DNA.

After DNA or RNA extraction, samples may require further preparation depending on the sequencing method.  For Sanger sequencing, either cloning procedures or PCR are required prior to sequencing. In the case of next-generation sequencing methods, library preparation is required before processing.<ref>{{cite journal |vauthors=Alberti A, Belser C, Engelen S, Bertrand L, Orvain C, Brinas L, Cruaud C, etal | year = 2014 | title = Comparison of Library Preparation Methods Reveals Their Impact on Interpretation of Metatranscriptomic Data | journal = BMC Genomics | volume = 15 | issue = 1 | pages = 912–12 | doi = 10.1186/1471-2164-15-912 | pmid=25331572 | pmc=4213505 | doi-access = free }}</ref> Assessing the quality and quantity of nucleic acids both after extraction and after library preparation identifies degraded, fragmented, and low-purity samples and yields high-quality sequencing data.<ref>{{cite web| url= https://www.illumina.com/content/dam/illumina-marketing/documents/products/appnotes/library-qc-fragment-analyzer-application-note-770-2017-002.pdf|title=Scalable Nucleic Acid Quality Assessments for Illumina Next-Generation Sequencing Library Prep|access-date=2017-12-27}}</ref>