00:01
Hello students, the question asked is suppose you performed a beta galactosidase assay on e.
00:17
Coli with i +, p +, oc, z +, and y - operon.
00:33
What results would you expect in the absence and presence of iptg? as we know that this iptg is an artificial inducer.
00:56
It works like the natural lactose.
01:01
And what naturally happens when lactose or iptg is absent then laci produces a protein called lac repressor and this lac repressor binds to the operator site and this binding of lac repressor to the operator sites prevents rna polymerase from binding to its promoter and carry out the transcription of genes lacz, y, and a which are naturally present in an e.
01:47
Coli operon and when the lactose or for that matter the artificial inducer iptg is present this binds with the lac repressor and inhibits its binding to the operator site so that rna polymerase can bind to the promoter and carry out the transcription of the genes.
02:14
So in absence of lactose or iptg there will be no transcription of genes since lac operon will bind to operator and in absence of lactose and in presence of lactose and iptg this it will bind to the lac repressor and it will not allow it to bind to the operator site which will result into the binding of rna polymerase on promoter site and the expression of genes lacz, y, and a.
02:44
Now let's consider this lac operon here in which we find that this plus sign means the gene is functional and hence their proteins will be functional and negative means the gene is non -functional and c means constitutive or we can say hyperactive operator...