DNA Extraction Simplified
For sure, you’ve heard about DNA or sometimes called as the Blueprint of Life or Genetic Code. From bacteria, plants, animals and us Humans, all living organisms have DNA in their cells. DNA is long molecules that are made up of nucleotides chain while the order of nucleotides have made organisms to come from the same species but with a different appearance. The genes are section in the long DNA molecules.
To be able to study the DNA, you first need to extract it out of the cell. In the eukaryotic cells similar to plant and human cells, the DNA is an organized chromosomes in organelle referred to as nucleus. The bacterial cells have none of this and so, their DNA is organized either in circular plasmids or rings which are found in cytoplasm. DNA extraction is freeing the DNA from the cells and separate it from the cellular fluid and proteins too. This way, what’s left is only the DNA in its purest form.
The truth is, there are three basic procedures when doing DNA extraction and these include Lysis, Precipitation and Purification. These steps will be discussed further in the next paragraphs.
Step number 1. Lysis – to release the DNA inside, this procedure breaks open the cell and the nucleus. Scientists basically use two ways of doing this which is via mechanical disruption and Lysis. In mechanical disruption, it is breaking open the cells which are done with tissue homogenizer, with a pestle or mortar or by cutting tissues in smaller pieces. This procedure is crucial especially when plant cells are used since they have tougher cell walls.
On the other hand, lysis use detergents and enzymes similar to Proteinase K to free up DNA and also, to dissolve cellular proteins present in it.
Step number 2. Precipitation – the DNA is freed from the nucleus upon the completion of lysis step but it is often mixed up with mashed up cells. The DNA will be separated from cellular debris through precipitation. First, sodium is used to neutralize negative charges present on DNA molecules making them less water soluble and more stable. The DNA isn’t soluble in alcohol like isopropanol or ethanol and for that, it’s used to trigger precipitation.
Step number 3. Purification – after the DNA is separated from aqueous phase, it will now be rinsed using alcohol. This step will then remove the remaining cellular debris and unwanted materials. At this stage of the procedure, the DNA is then re-dissolved in water.