00:01
Hello everyone, in this question we will be talking about the lac operon.
00:05
So here we have been given that the lac repressor inhibits the lac operon whereas the cap here stimulates the operon.
00:21
So let us here make the lac operon transcript.
00:25
So here we have the promoter sequence of the lac i gene and then we have the promoter sequence for the lac operon.
00:38
There is operator sequence.
00:39
There is the structural gene.
00:42
So basically when the lac i is transcribed by the rna polymerase, it is translated into the repressor which binds to the operator and therefore do not allow the rna polymerase to transcribe the operon and therefore no transcription take place.
01:03
This happens when the lac dose is low and glucose is high.
01:08
Also, there is the crp -camp complex which binds to the upstream of the promoter but glucose inhibits the adenylyl cyclase and therefore the cyclic amp is not produced.
01:22
Now, if we reverse the situation here, let us say that the glucose is low and lac dose is high.
01:31
So now this complex will be formed and this will act as the positive stimulator of the lac operon gene.
01:38
So in this case, the allolactose form of the lactose will bind to this repressor and this will become inactive and therefore now it cannot bind to the operator sequence and that is why now the rna polymerase could transcribe the gene here.
01:57
So the z gene codes for beta -galactosidase which breaks the lactose into galactose plus glucose...