DNA Isolation

DNA extraction is the process of removing and purifying DNA from cells.

First, cells are lysed or broken open, usually through a combination of physical disruption and treatment with chemicals such as detergents that dissolve the cell and nuclear membranes.

The cellular contents are then released into the solution.

Next, the DNA is separated from the other molecules present in the sample.

Protease enzymes are added to degrade proteins, followed by RNase treatment to degrade RNA while leaving the DNA intact.

Following this, phenol and chloroform are added to separate DNA from proteins and other cellular components. The sample is centrifuged to separate the aqueous and organic phases. Because DNA is water-soluble, it remains in the aqueous layer, while proteins and cellular debris remain in the organic phase.

The aqueous layer containing the DNA is then collected, and salt is added. The positively charged ions from the salt neutralize the negatively charged phosphate groups in the DNA backbone.

Then, ice-cold ethanol is added. Because DNA is much less soluble in ethanol than in water, the neutralized DNA molecules clump together and precipitate out of the solution.

The DNA precipitate is centrifuged, causing it to settle at the bottom of the tube and form a pellet.

After washing and resuspending the DNA pellet in a buffer solution, the extracted DNA can be used in research or biotechnology applications.