The enzyme β-galactosidase helps in the selection of recombinants.
• It identifies the recombinants from non recombinants by a process called insertional inactivation.
• When a recombinant DNA is inserted in the coding sequence of enzyme β-galactosidase, the enzyme becomes inactive. This is known as insertional inactivation.
• If the plasmid of the bacteria does not have an insert, then the blue color colonies are produced.
• The production of blue colored colonies is due to chromogenic substances.
• If the insert is present in the plasmid, then the enzyme becomes inactive and the colonies produced do not have any color.
• In this way recombinant colonies are separated from non recombinants.
Also, selection of recombinants by inactivation of antibiotics is a very hectic procedure.
Hence, β-galactosidase enzyme site is a preferred selectable marker in comparison to antibiotic resistant selectable marker in biotechnology experiments.
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