Step 1- Isolate DNA out of the cell
Step 2 - Centrifuge down the fragments at low rpm
Step 4 - Concentrate DNA using 2 volumes of ethanol
Step 5 - Confirm DNA purity - A260/A280 > 1.8 indicates pure DNA.
DNA is extracted from cells by lysis. The different types of lysis include:
- Biological methods such as using lytic enzymes.
- Physical methods such as using freeze-thaw and osmotic pressure to burst the cells.
- Mechanical methods such as grinding or shearing.
Grinding methods include using a pestle and mortar, primarily used for plant cells, using a bead mill for tough samples or vortexing.
Shearing methods include using a homogeniser, a rotor-stator or syringe needle.
DNA may be purified by adding phenol-chloroform mixture or via a commercial kit which is a lot easier and quicker. Commercial methods are preferred due to accuracy and ease of reproducing experiments. The DNA retrieved via these kits is also usually purer than when Phenol-Chloroform is used. The kits are also not hazardous, unlike the Phenol-Chloroform version.