Editing DNA extraction (section)

{{Short description|Process of isolating DNA from cells}}
{{For|the various methods|Nucleic acid methods}}
{{More citations needed|date=May 2014}}

The first isolation of [[deoxyribonucleic acid]] (DNA) was done in 1869 by [[Friedrich Miescher]].<ref name=":0">{{Cite web |title=Fluorescence In Situ Hybridization (FISH) |url=https://www.genome.gov/genetics-glossary/Fluorescence-In-Situ-Hybridization |access-date=2022-10-23 |website=Genome.gov |language=en}}</ref>  '''DNA extraction''' is the process of isolating DNA from the cells of an organism isolated from a sample, typically a biological sample such as blood, saliva, or tissue. It involves breaking open the cells, removing proteins and other contaminants, and purifying the DNA so that it is free of other cellular components. The purified DNA can then be used for downstream applications such as [[Polymerase chain reaction|PCR]],<ref>{{Cite journal |last=Gupta |first=Nalini |date=2019 |title=DNA extraction and polymerase chain reaction |url=http://www.jcytol.org/text.asp?2019/36/2/116/251448 |journal=Journal of Cytology |language=en |volume=36 |issue=2 |pages=116–117 |doi=10.4103/JOC.JOC_110_18 |issn=0970-9371 |pmc=6425773 |pmid=30992648 |doi-access=free }}</ref> [[DNA sequencing|sequencing]], or [[Cloning vector|cloning]]. Currently, it is a routine procedure in [[molecular biology]] or [[forensics|forensic]] analyses.

This process can be done in several ways, depending on the type of the sample and the downstream application,<ref>{{Cite book |title=DNA Extraction - an overview {{!}} ScienceDirect Topics |url=https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dna-extraction |access-date=2023-01-27 |isbn=978-0-12-821710-8 |last1=Srivastava |first1=Akhileshwar Kumar |last2=Kannaujiya |first2=Vinod Kumar |last3=Singh |first3=Rajesh Kumar |last4=Singh |first4=Divya |date=5 October 2020 |publisher=Elsevier Science }}</ref> the most common methods are: mechanical, chemical and enzymatic lysis, precipitation, purification, and concentration. The specific method used to extract the DNA, such as phenol-chloroform extraction, alcohol precipitation, or silica-based purification.<ref>{{Cite journal |last1=Dehasque |first1=Marianne |last2=Pečnerová |first2=Patrícia |last3=Kempe Lagerholm |first3=Vendela |last4=Ersmark |first4=Erik |last5=Danilov |first5=Gleb K. |last6=Mortensen |first6=Peter |last7=Vartanyan |first7=Sergey |last8=Dalén |first8=Love |date=2022-04-13 |title=Development and Optimization of a Silica Column-Based Extraction Protocol for Ancient DNA |journal=Genes |language=en |volume=13 |issue=4 |pages=687 |doi=10.3390/genes13040687 |issn=2073-4425 |pmc=9032354 |pmid=35456493|doi-access=free }}</ref>

For the chemical method, many different kits are used for extraction, and selecting the correct one will save time on kit optimization and extraction procedures. [[Polymerase chain reaction|PCR]] sensitivity detection is considered to show the variation between the commercial kits.<ref>{{cite journal | vauthors = Yoshikawa H, Dogruman-Al F, Dogruman-Ai F, Turk S, Kustimur S, Balaban N, Sultan N | title = Evaluation of DNA extraction kits for molecular diagnosis of human Blastocystis subtypes from fecal samples | journal = Parasitology Research | volume = 109 | issue = 4 | pages = 1045–50 | date = October 2011 | pmid = 21499752 | doi = 10.1007/s00436-011-2342-3 | s2cid = 37191780 }}</ref>

There are many different methods for extracting DNA, but some common steps include:

# Lysis: This step involves breaking open the cells to release the DNA. For example, in the case of bacterial cells, a solution of detergent and salt (such as [[SDS-PAGE|SDS]]) can be used to disrupt the cell membrane and release the DNA. For plant and animal cells, mechanical or enzymatic methods are often used.
# Precipitation: Once the DNA is released, proteins and other contaminants must be removed. This is typically done by adding a precipitating agent, such as alcohol (such as ethanol or isopropanol), or a salt (such as [[ammonium acetate]]). The DNA will form a pellet at the bottom of the solution, while the contaminants will remain in the liquid.
# Purification: After the DNA is precipitated, it is usually further purified by using column-based methods. For example, silica-based spin columns can be used to bind the DNA, while contaminants are washed away. Alternatively, a [[centrifugation]] step can be used to purify the DNA by spinning it down to the bottom of a tube.
# Concentration: Finally, the amount of DNA present is usually increased by removing any remaining liquid. This is typically done by using a vacuum centrifugation or a [[Freeze-drying|lyophilization]] (freeze-drying) step.

Some variations on these steps may be used depending on the specific DNA extraction protocol. Additionally, some kits are commercially available that include reagents and protocols specifically tailored to a specific type of sample.<ref>{{Cite journal |last1=Fahle |first1=Gary A. |last2=Fischer |first2=Steven H. |date=October 2000 |title=Comparison of Six Commercial DNA Extraction Kits for Recovery of Cytomegalovirus DNA from Spiked Human Specimens |journal=Journal of Clinical Microbiology |language=en |volume=38 |issue=10 |pages=3860–3863 |doi=10.1128/JCM.38.10.3860-3863.2000 |pmid=11015421 |pmc=87494 |issn=0095-1137}}</ref>