Lab, Medical

DNA & RNA Extraction – How & Why It’s Done

DNA and RNA extraction is one of the most basic things in molecular biology. And it is done for many reasons. Extraction allows for microbiologists and researchers to study the genetic causes of diseases, detecting bacteria, viruses, and gene sequencing


DNA and RNA extraction is similar in many aspects, but one of the main differences is that pH levels of DNA post-extraction are around ph8 while pH levels of RNA are around 4.7 post-extraction. But DNA then goes through the denature process while RNA goes through alkaline hydrolysis which moves both to opposite sides of the pH scale. During the extraction process, there are tools that one uses to transfer and isolate those liquids, such as filter tips. 10ul filter tips are just one of the volumes, with bigger volumes available as needed. 


DNA and RNA extraction is essential to the isolation and purification of nucleic acid from cells. DNA and RNA have long been an essential part of molecular biology, genomics, biotechnology and more. And as the world of biotech and molecular biology gets more and more complex, the roles of DNA and RNA get more involved too. First of all, let’s take a look at what DNA and RNA extraction is.


DNA Extraction 

To isolate and purify samples of DNA inside a mixture is called DNA extraction. There are many things that DNA can be extracted from such as saliva samples, blood samples, frozen tissue samples, paraffin tissues and more. Moreover, the process of DNA extraction can be divided into three steps. 

  • Cell Lysis

It is when the membrane barriers of the cell and its nucleus break open exposing the raw DNA sample ready to be extracted properly. 

  • DNA Isolation

This is the main extraction process where the DNA is derived and the membrane lipids are removed from the sample. 

  • Precipitation

This final step is where the DNA sample is purified by removing any excess proteins and the removal of RNA and RNase from the sample, leaving behind a pure DNA sample ready to be analyzed.


RNA Extraction

Similar to DNA, the RNA extraction process also refers to the extraction and purifying of an RNA sample from a cell. The Guanidinium Thiocyanate-Phenol-Chloroform Extraction is the name of the official RNA extraction process. The main purpose of this process is to denature the proteins and disrupt the hydrogen bonding process of any water sample. A chemical called the tri-reagent is used in the extraction process. But there is a certain protocol that an RNA extraction process follows:

  1. The sample is washed with PBS, then aspirated and homogenized with the tri-reagent.
  2. The chloroform is added after which the samples are put through centrifugation; three layers form, the first is aqueous, the middle contains the sample, the last is the organic layer.
  3. The aqueous layer is removed and isopropanol is added, leading to the crystallization of the middle layer containing the RNA sample. This can later be dissolved and put through analysis.


This extraction process can also be used to extract the DNA from proteins. 


Similarities Between the Processes

  1. They are both procedures of isolating and purifying nucleic acids from biological samples.
  2. Both procedures involve cell lysis, purification, and removal of excessive proteins.
  3. Both procedures require the environmental conditions to be cold.
  4. Centrifugation is necessary to separate the components in both mixtures.
  5. The activity of nuclease enzymes needs to be stopped during the procedures.
  6. Phenol-chloroform is a chemical required in both extractions.
  7. Nucleic acids in cells in both procedures can be protected by Guanidinium Thiocyanate.
  8. The precipitation process of RNA can be done with isopropanol just like DNA
  9. In both extraction procedures, one can use Sodium Acetate to increase the precipitation levels. 



The procedure of DNA extraction is done when the pH level is 8. Because after that, the protein in it denatures to the alkaline side. While RNA is done at a higher pH before it has a chance to go through the alkaline hydrolysis process and move towards the acidic side of the pH scale.


To make this process more efficient and simplified, we at MBP Inc offer Automated Nucleic Acid Extraction System machines to you at great prices that will help you in a lab environment at getting the samples you want quickly. We also offer other instruments, chemical reagents and lab equipment such as filter tips for Rainin LTS and such to better aid you in your research and speed up the process.



[1]  J. Nath, “Difference Between DNA and RNA Extraction,” 1 June 2018. [Online]. Available: [Accessed 6 December 2021].


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