Maharashtra BoardEnglish MediumSTD 12 ScienceBIOLOGYBiotechnology: Principles and Processes5 Marks
Question
Explain insertional inactivation.
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Answer
The selection of recombinants due to inactivation of antibiotic gene is a cumbersome procedure, because it requires simultaneous plating on two plates having different antibiotics. Therefore, the alternative selectable markers have been developed, Which differentiate recombinants from non- recombinants. It is based on their ability to produce colour in the presence of chromogenic substrate.
In this process, a recombinant DNA is inserted within the coding sequence of an enzyme $\beta-$galactosidase. This result into inactivation of the enzyme, which is referred to as insertional inactivation. Therefore, the bacterial colonies having inserted plasmid, shows no colouration (recombinant colonies) while, those without ptasmid will show blue colour. Here $\beta-$galactosidase works as a reporter enzyme (produced by reporter gene) whose inactivity helps to identify transformed and non-transformed bacterial colonies.
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