Difference Between Random Mutagenesis and Site Directed Mutagenesis

Key Difference – Random Mutagenesis vs Site Directed Mutagenesis
 

Mutagenesis is the process in which mutations are purposely introduced to cells or genes that will result in genetically modified genes or organisms. Mutagenesis is mostly done to introduce beneficial characteristics to organisms. Presently mutagenesis is also used in gene therapy to alter genes and for medicinal purposes. Mutations can be introduced in two main ways; Random mutagenesis and Site directed mutagenesis. Random mutagenesis is the process of introducing mutations randomly. Then select the organisms that are mutated using a selection method. The process is entirely random. Site Directed mutagenesis is the process in which mutations are introduced in a site-specific manner to specific locations in the DNA or to specific nucleotides. Specificity of site directed mutations in very high. The key difference between random and site directed mutagenesis is the fashion in which the mutation is introduced. Random mutagenesis introduces mutations in a random fashion, whereas site directed mutations are specifically targeted at selected sites of the genes.

CONTENTS

1. Overview and Key Difference
2. What is Random Mutagenesis
3. What is Site Directed Mutagenesis
4. Similarities Between Random Mutagenesis and Site Directed Mutagenesis
5. Side by Side Comparison – Random Mutagenesis vs Site Directed Mutagenesis in Tabular Form
6. Summary

What is Random Mutagenesis?

Random mutagenesis refers to the process of introducing mutations to organisms in a random fashion and thus is non-specific. Random mutagenesis involves exposing the organism into a mutagen for a period of time and selecting the mutant varieties. The mutagens can be either physical mutagens like UV radiation or chemical mutagens like alkylating agents. This method is best suited to induce mutations in microorganisms, plants, and animals.

The microbial strain development process in antibiotic production is based on random mutagenesis. The antibiotic-producing strains are exposed to different mutagens and then the antibiotic susceptibility of the strain is tested. Thereby, the strains that have developed resistance over the original strain can be deduced.

In plant tissue culture, random mutagenesis is used to incorporate different characters into the plants. Plants are exposed to mutagens in the callus forming stages. In animal studies, random mutagenesis is rarely used, although alkylating agents have been used to induce mutations via random mutagenesis.

When exposing organisms for mutagens, care should be taken about the dose of the mutagen and the period of exposure to the mutagens. Excess doses and exposure periods can damage the organism itself. Therefore, random mutagenesis should be done under controlled conditions.

What is Site Directed Mutagenesis?

Site directed mutagenesis is a more specific process of inducing mutations, where base analogs were used to create point mutations. These base analogs are capable of inducing Adenine–Thymine to Guanine–Cytosine transitions. In this manner, the mutation is induced and it is known as site directed mutagenesis and therefore has a high specificity.

In early molecular biology techniques, the site directed mutagenesis using base analogs were done using aminopurine for AT – GC transitions and nitrosoguanidine for GC to AT transitions. With the introduction of Polymerase Chain Reaction (PCR) and the concept of primers, currently, the site directed mutagenesis is induced via mutagenic oligonucleotides. This method allows the insertion of indels, and point mutations to the selected gene or organism. Upon completion of the mutagenesis procedure, the mutants are selected by using specific reporters or markers.

What are the Similarities Between Random Mutagenesis and Site Directed Mutagenesis?

• Both Random Mutagenesis and Site Directed Mutagenesis techniques are artificial methods of inducing a mutation to a specific organism.
• Both Random Mutagenesis and Site Directed Mutagenesis techniques are used to produce beneficial varieties of organisms which possess characteristics such as disease tolerance and in gene therapy.
• Both Random Mutagenesis and Site Directed Mutagenesis techniques induce mutations in DNA and alter the DNA.
• Both Random Mutagenesis and Site Directed Mutagenesis types are induced mainly by physical and chemical agents.

What is the Difference Between Random Mutagenesis and Site Directed Mutagenesis?

Summary – Random Mutagenesis vs Site Directed Mutagenesis 

Mutations are changes in the DNA sequence of an organism. These are due to unknown exposures of mutagens. In mutagenesis, varieties of microorganisms, plants and animal cell cultures are exposed to mutagens and the mutant variety is selected after the completion of the gene transfer. Depending on the manner in which the mutation is brought about, they can either be Random mutations or site-directed mutations. Random mutagenesis is the process of introducing mutations randomly while Site Directed mutagenesis is the process in which mutations are introduced in a site-specific manner to specific locations in the DNA or to specific nucleotides. This is the difference between Random mutagenesis and Site Directed mutagenesis.

Reference:

1.“Mutagenesis (Molecular biology technique).” Mutagenesis (Molecular biology technique) – an overview | ScienceDirect Topics. Available here
2.Sturtevant, Joy. “Site-Directed and Random Insertional Mutagenesis in Medically Important Fungi.” Site-Directed and Random Insertional Mutagenesis in Medically Important Fungi | InTechOpen, InTech, 5 Feb. 2013.  Available here

Image Courtesy:

1.’Site Directed Mutagenesis’By Knbusby – Own work, (Public Domain) via Commons Wikimedia