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DNA & RNA Purification

Structure of DNA – various methods are used for DNA purification

Extraction of DNA and RNA is a basic method used in molecular biology. The need for high-quality, highly pure nucleic acid is important for a wide range of research and clinical applications. Nucleic acid purification is an initial step in many molecular biology and genomic workflows.

DNA and RNA samples are often obtained from crude preparations. Genomic DNA, plasmid DNA, and total RNA can be extracted and purified from a variety of sources including bacterial and mammalian cells, plant tissue, fungal tissue, mammalian tissue, blood, plasma, serum, viruses, buccal and nasal swabs, gel matrices, PCRs, and other enzymatic reactions. Isolation of nucleic acid from these samples often involves the lysis of cell membranes or sample homogenization, followed by the removal of proteins, enzymes, detergents, salts, and lipids.

Common approaches include:

  • Alkaline extraction
  • Phenol-chloroform extraction
  • Cesium chloride (CsCl) density gradient centrifugation
  • Oligo(dT)-cellulose chromatography
  • Silica matrice
  • Glass beads
  • Diatomaceous earth
  • Anion exchange chromatography
  • Size exclusion chromatography


The final application will dictate the best method for purification. Downstream applications include PCR, qPCR, restriction digests, ligation, cloning, genotyping, gene expression analysis, next generation sequencing (NGS), and Northern and Southern blotting.


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