Name: steps in dna extraction
Uploaded: 2026-08-26T08:20:38.799Z
Duration: 1 min 58 s
Channel: JoVE

L&#x27;extraction d&#x27;ADN est l&#x27;enl&#xE8;vementet la purification de l&#x27;ADN des cellules. 
D&#x27;abord, les cellules sont lys&#xE9;es, ouvertes,g&#xE9;n&#xE9;ralement par une combinaison de perturbations physiqueset de traitements chimiques comme avec un d&#xE9;tergentce qui dissout la cellule et les membranes nucl&#xE9;aires. 
Le contenu peut alors flotter librementdans la solution environnante. 
Ensuite, l&#x27;ADN doit &#xEA;tre s&#xE9;par&#xE9;des autres mol&#xE9;cules pr&#xE9;sentes. 
Des solvants organiques, comme le ph&#xE9;nol et le chloroforme,sont couramment utilis&#xE9;s pour s&#xE9;parerles acides nucl&#xE9;iques des prot&#xE9;inesen raison de leur solubilit&#xE9; diff&#xE9;rente. 
En outre, les enzymes prot&#xE9;inase et RNasepeuvent &#xEA;tre utilis&#xE9;es pour d&#xE9;grader les prot&#xE9;ines et l&#x27;ARN,laissant l&#x27;ADN intact. 
Le sel est g&#xE9;n&#xE9;ralement ajout&#xE9; &#xE0; l&#x27;&#xE9;chantillonce qui stabilise les groupes phosphate charg&#xE9;s n&#xE9;gativementdans la structure de l&#x27;ADN,et apr&#xE8;s l&#x27;ajout d&#x27;alcool glac&#xE9;,pr&#xE9;cipite l&#x27;ADN hors de la solution. 
Le pr&#xE9;cipit&#xE9; blanc est recueillien le faisant tourner dans une centrifugeuseo&#xF9; il se d&#xE9;pose au fond du tube. 
Apr&#xE8;s lavage et re-suspensiondans une solution tampon,l&#x27;ADN extrait peut enfin &#xEA;tre utilis&#xE9; en rechercheou en biotechnologie.

isolement de l'adn

DNA Isolation

L&#x2019;ADN des cellules est n&#xE9;cessaire pour de nombreuses applications de biotechnologie et de recherche, telles que le clonage mol&#xE9;culaire. Pour enlever et purifier l&#x2019;ADN des cellules, les chercheurs utilisent diverses m&#xE9;thodes d&#x2019;extraction de l&#x2019;ADN. Bien que les sp&#xE9;cificit&#xE9;s des diff&#xE9;rents protocoles puissent varier, certains concepts g&#xE9;n&#xE9;raux sont &#xE0; la base du proc&#xE9;d&#xE9; d&#x2019;extraction de l&#x2019;ADN.
 
 <h4>Le proc&#xE9;d&#xE9;</h4> 
 
 Tout d&#x2019;abord, les cellules doivent &#xEA;tre lys&#xE9;es &#x2014; ouvertes &#x2014; pour lib&#xE9;rer l&#x2019;ADN dans la solution. Les cellules peuvent &#xEA;tre physiquement lys&#xE9;es &#xE0; l&#x2019;aide d&#x2019;&#xE9;quipements tels qu&#x2019;un homog&#xE9;n&#xE9;isateur, un sonicateur ou un broyeur &#xE0; billes, qui broient ou sinon appliquent de la force pour briser les cellules ouvertes. Souvent, des substances telles que du d&#xE9;tergent sont ajout&#xE9;es pendant la lyse pour perturber chimiquement les membranes cellulaires &#xE0; base de lipides, ce qui aide &#xE0; lib&#xE9;rer l&#x2019;ADN du noyau et de la cellule. La rotation dans une centrifugeuse s&#xE9;dimente les d&#xE9;bris cellulaires vers le fond et le lysat, contenant le mat&#xE9;riel cellulaire, est recueilli pour un traitement ult&#xE9;rieur.
 
 L&#x2019;ADN doit alors &#xEA;tre s&#xE9;par&#xE9; des autres mol&#xE9;cules cellulaires, telles que l&#x2019;ARN et les prot&#xE9;ines. Par cons&#xE9;quent, des enzymes telles que la RNase et la prot&#xE9;inase K sont souvent ajout&#xE9;es pendant ou apr&#xE8;s la lyse pour d&#xE9;grader l&#x2019;ARN et les prot&#xE9;ines, respectivement. En outre, des solvants organiques tels que le ph&#xE9;nol et le chloroforme sont couramment utilis&#xE9;s pour s&#xE9;parer l&#x2019;ADN des prot&#xE9;ines. Normalement, l&#x2019;&#xE9;chantillon est vortex&#xE9; avec du ph&#xE9;nol-chloroforme, puis centrifug&#xE9; pour s&#xE9;parer les phases aqueuse et organique dans le tube. La phase aqueuse au-dessus contenant l&#x2019;ADN peut alors &#xEA;tre pipett&#xE9;e, laissant derri&#xE8;re elle la prot&#xE9;ine dans la phase organique.
 
 Des sels sont souvent ajout&#xE9;s lors de l&#x2019;extraction de l&#x2019;ADN pour stabiliser l&#x2019;ADN et aider &#xE0; le pr&#xE9;cipiter hors de solution. Une m&#xE9;thode standard de pr&#xE9;cipitation d&#x2019;ADN consiste &#xE0; ajouter de l&#x2019;alcool glac&#xE9;, comme l&#x2019;&#xE9;thanol ou l&#x2019;isopropanol, &#xE0; l&#x2019;&#xE9;chantillon. Cela fait que l&#x2019;ADN forme un pr&#xE9;cipit&#xE9; trouble blanc &#xE0; l&#x2019;int&#xE9;rieur du liquide dans le tube.
 
 On fait ensuite tourner l&#x2019;&#xE9;chantillon dans une centrifugeuse, ce qui a pour effet de rassembler le pr&#xE9;cipit&#xE9; de l&#x2019;ADN au fond du tube comme un culot. Le culot est lav&#xE9; en enlevant le liquide, en le lavant dans l&#x2019;alcool et en le faisant tourner &#xE0; nouveau. Apr&#xE8;s le lavage final, le culot est remis en suspension dans un tampon, cr&#xE9;ant une solution aqueuse d&#x2019;ADN purifi&#xE9; qui est pr&#xEA;te &#xE0; &#xEA;tre &#xE9;tudi&#xE9;e ou utilis&#xE9;e en biotechnologie.

Isolement de l'ADN

DNA from cells is required for many biotechnology and research applications, such as molecular cloning. To remove and purify DNA from cells, researchers ...

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steps in dna extraction

DNA extraction is the process of removing and purifying DNA from cells. It is used in many biotechnology and research applications, including molecular cloning. The main goal is to free DNA from the cell and prepare it for later study or use.

The first step is cell lysis, which means breaking cells open. Researchers may use a homogenizer, sonicator, or bead beater to physically lyse the cells. They also often add detergent to chemically disrupt the lipid-based cell membranes. This helps release DNA from the nucleus and the rest of the cell.

After lysis, the sample is spun in a centrifuge. This causes cell debris to settle at the bottom, while the liquid lysate is kept for the next steps. The DNA then has to be separated from other cellular molecules, such as RNA and proteins. Enzymes like RNase and Proteinase K are often added to break down RNA and proteins, and phenol-chloroform can be used to separate DNA from protein.

During the phenol-chloroform step, the sample is vortexed and centrifuged again. The tube separates into an aqueous phase and an organic phase. The DNA stays in the aqueous phase at the top, and this layer can be pipetted off. Salts are often added to help stabilize the DNA and support precipitation.

To collect the DNA, ice-cold alcohol such as ethanol or isopropanol is added. The DNA then forms a white, cloudy precipitate in the tube. Another centrifuge spin pulls this DNA into a pellet at the bottom. The pellet is washed with alcohol, spun again, and then re-suspended in buffer to make a purified DNA solution ready for biotechnology work.

Steps in DNA Extraction

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dna isolation

DNA extraction is the process of removing and purifying DNA from cells. It is used in many biotechnology and research applications, including molecular cloning. The main goal is to free DNA from the cell and prepare it for later study or use. The first step is cell lysis, which means breaking cells open. Researchers may use a homogenizer, sonicator, or bead beater to physically lyse the cells. They also often add detergent to chemically disrupt the lipid-based cell membranes. This helps...

recombinant dna technology

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Knockout Mice and Gene Replacement

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reproductive cloning

Cloning Animals with SCNT

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genomics

Genomics and DNA Sequencing

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key terms and concepts

Learn the main steps in DNA extraction, including cell lysis, centrifugation, protein removal, and DNA precipitation for purified samples.

Steps in DNA Extraction | JoVE K12

JoVE Core series brings biology to life through over 300 concise and easy-to-understand animated video lessons that explain key concepts in biology, plus more than 150 scientist-in-action videos that show actual research experiments conducted in today’s laboratories.

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La collection JoVE Core Biologie donne vie à la biologie à travers plus de 300 leçons vidéos animées concises et faciles à comprendre qui expliquent les concept clés de la biologie, mais aussi plus de 150 vidéos de scientifiques à l'action effectuant des expériences de recherche dans des laboratoires modernes.

Steps in DNA Extraction

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