The Basics of DNA Purification

Before performing an PCR reaction or cloning experiment, or even DNA sequencing, it is crucial to have a high-quality DNA source that is free of contaminations such as particles, proteins and RNA. The process of purifying DNA is referred to as DNA isolation and is one of the most important steps in molecular biology. In this article, you will discover the fundamentals of DNA purification as well as how to improve your DNA extraction processes for more efficient results.

The initial step of the DNA purification process is to make a solution that consists of the mixture of water and alkaline buffer. This buffer makes DNA soluble and it is easily separated from other components in the sample. After the DNA is placed DNA purification steps in a water and alkaline solution, it is then treated by chaotropic salts or detergents to destroy cell membranes and nuclei and release DNA (cell lysis). RNase can be added into the sample to remove any DNA that is contaminating.

The DNA is separated by organic solvents such chloroform or phenol from the other components of the cell like fats and proteins. Once the DNA is removed from lipids or proteins and lipids, it can be precipitated by ethanol or rubbing alcohol.

The purity of the DNA may be verified using spectrophotometry or gel electrophoresis. A good quality DNA sample must have a ratio of absorbance between 260 and 282 nm. 1.8. A low ratio could signal a problem with the protein binding processes or the carryover of salt from wash or bind buffers.