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The Basics of DNA Purification

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Before making any PCR reaction or cloning test or DNA sequencing, it is essential to have high-quality DNA which is free of contaminants such as debris, protein and RNA. Purifying DNA is also referred to as DNA Isolation, and is an essential step in molecular biology. In this article you will discover the fundamentals of DNA purification, and how to optimize your DNA extraction strategies to get better results.

The first step in the DNA purification procedure is to make a solution consisting of an amalgamation of alkaline buffer and water. This buffer makes the DNA soluble and so that it can be easily separated from the other components of the sample. After the DNA is placed in a water and alkaline solution, it is treated by chaotropic salts or detergents to destroy cell membranes and nuclei, and release the DNA (cell lysis). RNase can be added to the sample to eliminate any contaminating DNA.

The DNA is separated by organic solvents such as chloroform or phenol from the other components of the cell including fats and proteins. After the DNA is removed from the proteins and lipids, it is able to be precipitated using ethanol or isopropyl alcohol (rubbing alcohol).

The quality of the DNA sample can be confirmed using spectrophotometry, or gel electrophoresis. A good quality DNA sample should have an absorbance value between 220 nm to 280 nm. 1.8. A low ratio could signal an issue with the protein binding steps or the transfer of salt from the bind or wash buffers.

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