The Basics of DNA Purification

Before making the PCR reaction or cloning test or DNA sequencing, it’s essential to have high-quality DNA which is free of contaminants such as debris, protein and RNA. The process of purifying DNA is referred to as DNA isolation and is one of the most crucial steps in molecular biology. In this article, you’ll discover the fundamentals of DNA purification, and how to optimize your DNA extraction methods to get more efficient results.

The first step of the DNA purification process is to make a solution consisting of the mixture of alkaline buffer and water. This buffer makes DNA soluble, so it is easy to separate from other components in the sample. After 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 lets the DNA out. RNase may also be added to eliminate any contaminating RNA from the sample.

DNA is then separated from other cellular components such as proteins and lipids, using organic solvents such as phenol and chloroform. Once the DNA is removed from the proteins or lipids it is then precipitated using alcohol or rubbing alcohol.

The quality of the DNA can be determined by spectrophotometry or gel electrophoresis. A good quality sample of DNA should have an absorbance ratio of between 250 nm and 280nm. 1.8. A low ratio could signal problems with the protein binding steps, or a salt carryover from wash or buffers that bind.

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