IPTG lac operon - study question PDF

Preview

Summary

study question...

Description

The compound IPTG is an analog of lactose which can induce the Lac operon but it is not hydrolysed by beta-galactosidase. Briefly describe how induction of the Lac operon by IPTG would differ from that by lactose. To describe how the induction of the lac operon would differ from lactose in IPTG’s case, we would first have to describe a general overview of how the lac operon is induced in the presence of lactose. In absence of it, the operon is continuously switched off. However, the presence of lactose forces the Lac tetramer repressor to separate from the operator and therefore allows the polymerase to start the transcription process. The lactose, if there are low levels of glucose, is then hydrolysed by the lacZ enzyme beta-galactosidase into two end products: glucose and galactose. Eventually, the lactose is used up completely, and the operon is switched back off. In the presence of IPTG, even though the lac repressor tetramer would still be displaced (therefore effectively ‘switching on’ the operon) beta-galactosidase would not generate neither glucose nor galactose. The IPTG therefore would not be used up or metabolised by the enzyme, which I suppose would either make the operon stay switched on for a longer period than that of lactose or would cause it to not switch off at all....