Question

3. Explain the structure and regulation of a typical bacterial inducible operon. Include DNA elements, DNA-binding proteins and possible outcomes in the presence/absence of an inducer.

Answer 1

The lactose operon is the bacterial regulated operon that is regulated by the presence of lactose which is a positive inducer.The repressor binds to the operstor region of lac operon which has three structural gene.On the presence of inducer lactose it binds to the repressor and so the repressor gets remove and RNAP gets access to the promoter and lac operon gets transcribed.It is also positively regulated by cap binding receptor protein and camp which binds the lac operon when the glucose concentration is less.So the lac operon DNA sequence can partially bend and contact RNAP to intiate expression. So binding of camp and camp cap protein is necessary to intiate expression.They can bind to the operon only when the easily metabolized sugar glucose is absenr in the media.