Editing Complementary DNA (section)

=== RNA purification ===
RNA is transcribed from genomic DNA in host cells and is [[RNA extraction|extracted]] by first [[Lysis|lysing]] cells then purifying RNA utilizing widely used methods such as phenol-chloroform, silica column, and bead-based RNA extraction methods.<ref>{{Cite journal |last=Tavares |first=Lucélia |last2=Alves |first2=Paula M. |author-link2=Paula Alves |last3=Ferreira |first3=Ricardo B. |last4=Santos |first4=Claudia N. |date=6 January 2011 |title=Comparison of different methods for DNA-free RNA isolation from SK-N-MC neuroblastoma |journal=BMC Research Notes |volume=4 |issue=1 |pages=3 |doi=10.1186/1756-0500-4-3 |issn=1756-0500 |pmc=3050700 |pmid=21211020 |doi-access=free}}</ref> Extraction methods vary depending on the source material. For example, extracting RNA from plant tissue requires additional reagents, such as polyvinylpyrrolidone (PVP), to remove phenolic compounds, carbohydrates, and other compounds that will otherwise render RNA unusable.<ref>{{Cite journal |last=R |first=Kansal |last2=K |first2=Kuhar |last3=I |first3=Verma |last4=Rn |first4=Gupta |last5=Vk |first5=Gupta |last6=Kr |first6=Koundal |date=December 2008 |title=Improved and Convenient Method of RNA Isolation From Polyphenols and Polysaccharide Rich Plant Tissues |journal=Indian Journal of Experimental Biology |language=en |volume=46 |issue=12 |pages=842–5 |pmid=19245182}}</ref> To remove DNA and proteins, enzymes such as DNase and Proteinase K are used for degradation.<ref>{{Cite journal |last=I |first=Vomelová |last2=Z |first2=Vanícková |last3=A |first3=Sedo |date=2009 |title=Methods of RNA Purification. All Ways (Should) Lead to Rome |journal=Folia Biologica |language=en |volume=55 |issue=6 |pages=243–51 |pmid=20163774}}</ref> Importantly, RNA integrity is maintained by inactivating RNases with chaotropic agents such as guanidinium isothiocyanate, sodium dodecyl sulphate (SDS), phenol or chloroform. Total RNA is then separated from other cellular components and precipitated with alcohol. Various commercial kits exist for simple and rapid RNA extractions for specific applications.<ref>{{Cite journal |last=Sellin Jeffries |first=Marlo K. |last2=Kiss |first2=Andor J. |last3=Smith |first3=Austin W. |last4=Oris |first4=James T. |date=14 November 2014 |title=A comparison of commercially-available automated and manual extraction kits for the isolation of total RNA from small tissue samples |journal=BMC Biotechnology |volume=14 |issue=1 |pages=94 |doi=10.1186/s12896-014-0094-8 |issn=1472-6750 |pmc=4239376 |pmid=25394494 |doi-access=free}}</ref> Additional bead-based methods can be used to isolate specific sub-types of RNA (e.g. [[Messenger RNA|mRNA]] and [[microRNA]]) based on size or unique RNA regions.<ref>{{Cite web |title=mRNA Isolation with Dynabeads in 15 minutes - US |url=https://www.thermofisher.com/us/en/home/life-science/dna-rna-purification-analysis/napamisc/mrna-isolation-dynabeads.html |access-date=20 May 2020 |website=www.thermofisher.com |language=en}}</ref><ref>{{Cite journal |last=Gaarz |first=Andrea |last2=Debey-Pascher |first2=Svenja |last3=Classen |first3=Sabine |last4=Eggle |first4=Daniela |last5=Gathof |first5=Birgit |last6=Chen |first6=Jing |last7=Fan |first7=Jian-Bing |last8=Voss |first8=Thorsten |last9=Schultze |first9=Joachim L. |last10=Staratschek-Jox |first10=Andrea |date=May 2010 |title=Bead Array–Based microRNA Expression Profiling of Peripheral Blood and the Impact of Different RNA Isolation Approaches |journal=The Journal of Molecular Diagnostics |volume=12 |issue=3 |pages=335–344 |doi=10.2353/jmoldx.2010.090116 |issn=1525-1578 |pmc=2860470 |pmid=20228267}}</ref>