DNA分离

DNA extraction is the removal and purification of DNA from cells. First cells are lysed, broken open. Usually through a combination of physical disruption and treatment with chemicals such as detergent which dissolves the cell and nuclear membranes. The content can then float freely into the surrounding solution.

Next DNA must be separated from the other molecules present. Organic solvents such as phenol and chloroform are commonly used to separate nucleic acids from proteins based on their differing solubility.Additionally, proteinase and RNase enzymes can be used to degrade proteins and RNA leaving the DNA intact.

Salt is usually added to the sample which stabilizes the negatively charged phosphate groups in the backbone of the DNA. And after the addition of ice cold alcohol, precipitates the DNA out of the solution. 

The white precipitate is collected by spinning it in a centrifuge where it settles to the bottom of the tube. After washing and re-suspending it in a buffer solution, the extracted DNA can finally be used in research or biotechnology applications.