Spread the love

Recombinant DNA technology and the use of synthetic DNA molecules make it possible for molecular biology scientists to induce specific mutations in specific genes. This is usually done to generate or produce a desired end-product. In vitro mutagenesis is used to purposefully change genetic information for either medical, economical, research or industrial applications. The analysis of the subsequent changes in gene expression and gene products helps elucidate the functional effect of the mutation. There are various types of mutagenesis. These different types of mutagenesis include:

  1. Site-directed mutagenesis
  2. Cassette mutagenesis
  3. Random mutagenesis

These examples are some of the major types of mutagenesis. It is noteworthy that the particular mutagenesis method you choose to use will depend on the goal of the project and the information you have about the target gene sequence to be altered. Site-directed mutagenesis creates a specific change in a known sequence of a gene while random mutagenesis allows researchers to screen for mutations regardless of the genomic location or to quickly create a wide variety of individual mutations. Cassette mutagenesis replaces a section of DNA sequence with a DNA fragment containing the mutated sequence.


Cassette mutagenesis is used to introduce multiple mutations into a given DNA sequence. Random mutagenesis creates mutations at undefined sites and does not require knowledge of sequence or function. Random mutagenesis is used to identify protein variants with desired properties as well as to understand the interaction of genes in biological pathways. Site-directed mutagenesis creates a mutation at a defined site and requires a known template sequence.

Site-directed mutagenesis allows researchers to investigate the impact of sequence changes, such as single nucleotide polymorphisms (SNPs), or to insert or delete a sequence element, such as a ligand binding site or restriction site. Site-directed mutagenesis can also be used to screen a variety of mutants to determine the optimal sequence for the question at hand. Site-directed mutagenesis is a method used to create specific, targeted changes in double stranded plasmid DNA molecule. It uses synthetic DNA in addition to DNA cloning techniques to introduce mutations into genes at precisely determined sites of a gene sequence. There are many reasons to make specific DNA alterations including insertions, deletions and substitutions in a given gene sequence.

Some of the major applications of site directed mutagenesis are highlighted below:

  • Site directed mutagenesis is used to study changes in protein activity that occurs as a result of the DNA manipulation. 
  • It is used to assess the activity of proteins containing known amino acid substitutions.
  • It is used to select or screen for mutations (at the DNA, RNA or protein level) that have a desired property; and which can be manipulated further for enhanced biological activity.
  • It is used to change specific amino acid in an enzyme. In this case, the modified enzyme molecule is assayed and compared to the wild-type enzyme molecule.
  • It is used to introduce or remove restriction enzymes or endonuclease sites or tags.
  • Site-directed mutagenesis helps scientists to study the mechanism of action behind biological reactions catalyzed by enzymes in vivo.

Further reading

Cooper G.M and Hausman R.E (2004). The cell: A Molecular Approach. Third edition. ASM Press.

Das H.K (2010). Textbook of Biotechnology. Fourth edition. Wiley edition. Wiley India Pvt, Ltd, New Delhi, India.

Davis J.M (2002). Basic Cell Culture, A Practical Approach. Oxford University Press, Oxford, UK. 

Mather J and Barnes D (1998). Animal cell culture methods, Methods in cell biology. 2rd eds, Academic press, San Diego.

Noguchi P (2003).  Risks and benefits of gene therapy.  N  Engl J Med, 348:193-194.

Sambrook, J., Russell, D.W. (2001). Molecular Cloning: a Laboratory Manual, 3rd edn. Cold Spring Harbor Laboratory Press, New York.

Tamarin Robert H (2002). Principles of Genetics. Seventh edition. Tata McGraw-Hill Publishing Co Ltd, Delhi.     

Be the first to comment

Leave a Reply

Your email address will not be published.