Before doing any PCR reaction or cloning experiment, or even DNA sequencing, it is essential to have high-quality DNA which is free of contaminants, such as protein, debris and RNA. Purifying DNA is also referred as DNA Isolation, and is an essential step in molecular biology. In this article you will learn the fundamentals of DNA purification as well as how to improve your DNA extraction processes to get better results.
The first step of the process of purifying DNA is to prepare a solution that contains a mixture of water and an alkaline buffer. This buffer makes DNA soluble, so it is able to be separated from the other components of the sample. Once the DNA has been placed in an alkaline and water solution it is then treated with detergents and salts that break down cells’ membranes and nuclei. This releases the DNA. RNase can also be added to eliminate any contamination RNA from the sample.
DNA is separated from other cellular components like proteins and lipids with the help of organic solvents like chloroform and phenol. Once the DNA has been removed from the proteins and lipids, it is able to be extracted using ethanol, or isopropyl alcohol (rubbing alcohol).
The purity of the DNA can then be assessed by spectrophotometry or gel electrophoresis. A high-quality DNA sample will have an absorbance ranging from 260 nm to at least 280 nm.
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