It is important to have high quality DNA that is free of contaminants like proteins, debris and RNA prior to performing a PCR as well as cloning or DNA sequencing. The process of purifying DNA is known as DNA isolation. It is one of the most critical steps in molecular biology. In this article you will be taught the fundamentals of DNA purification as well as how to improve your DNA extraction processes for better results.
The first step in the DNA purification process is to prepare a solution that comprises a mixture of water and an alkaline buffer. This buffer makes DNA soluble, so it is easily separated from other components of the sample. Once the DNA has been placed in a water and alkaline solution, it is treated by chaotropic salts or detergents to remove cell membranes and nuclei to release DNA (cell lysis). RNase can be added to the sample in order to remove any contaminating DNA.
DNA is separated from other cellular components such as proteins and lipids, using organic solvents such as phenol and chloroform. After the DNA is separated from lipids or proteins it can be precipitated with alcohol or rubbing alcohol.
Spectrophotometry and electrophoresis may be used to determine the quality of DNA. A high-quality DNA sample should have an absorbance ratio of between the 260-nm range and 280-nm range.
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