DNA and RNA Extraction - Important Differences

DNA extraction and RNA extraction are both procedures that involve isolating and purifying nucleic acids from cells. Superior quality DNA and RNA find applications in biotechnology, molecular biology, epidemiology and genomic demonstrations.

It is necessary to extract pure RNA and DNA samples to perform experimental processes in studying different streams.

Main Difference between DNA extraction and RNA extraction

The key difference between DNA and RNA extraction lies in the pH levels. To extract DNA, the pH required is 8, while for that of RNA extraction it is 4.7. The DNA has a tendency to denature and pass into the organic stage at a pH that is acidic. The RNA in an alkaline environment experiences alkaline hydrolysis as a result of the 2′ OH in the ribose sugar.

Also, there is another important difference. The RNA extraction process purifies RNA while the DNA extraction process purifies DNA. The process of extraction of DNA advances through these stages – catabolism of membrane proteins and lipids, cell lysis, clumping of catabolites by concentrated salt solution, along with the precipitation of DNA in the presence of ethanol. This 3-step process can comprise two elective steps

The process of RNA purification comprises 4 distinct stages – cell lysis, denaturation of proteins, RNA separation by adding chloroform and phenol and then cleaning precipitate using ethanol.

DNA Extraction

  • It involves isolating and purifying DNA and is a chemical and physical process
  • Samples of DNA can be obtained from paraffin tissue blocks, blood, tissue samples (frozen)
  • It takes place in the following steps – cell lysis, DNA isolation and precipitation
  • Once the cell is lysed, concentrated salt solutions promote clumping of catabolized molecules
  • Then solution undergoes centrifugation separating DNA from debris clumps
  • The DNA that is differentiated is combined with the salts and reagents used at the time of the cell cycle
  • Ethanol precipitation can be used to purify it further

RNA Extraction

  • From a biological sample, RNA is purified
  • The process gets complex due to the presence of ribonuclease in the tissues and cells
  • RNA can be rapidly degraded using ribonuclease enzyme
  • A common method involved in RNA extraction is Guanidinium thiocyanate-phenol-chloroform extraction, which is based on the principle of centrifugation and phase separation

Key Differences Between DNA and RNA Extraction

The table below depicts the differences between DNA and RNA Extraction.

DNA Extraction

RNA Extraction

What is the process about?

Involves the isolation and purification of DNA

RNA is purified in the process from the sample

What is purified?

DNA

RNA

What is pH level?

8

4.7

Steps

Cell lysis, membrane lipids removed, DNA precipitation

Cell lysis, Guanidinium thiocyanate-phenol-chloroform extraction, preparation with isopropanol

When is the extraction carried out?

Can be extracted before and stored in batches

It is carried out just before the downstream process

Reagents used in the extraction

Sodium acetate, surfactants, chloroform, alcohol, phenol

Phenol, chloroform, ethanol, Guanidium thiocyanate

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