In the Absence of Lactose

by Jason Amores Sumpter
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in this video, we're going to continue to talk about the lack Opteron, specifically in the absence of lactose. And so before we even move on here, recall from our previous lesson videos that the lack opera is only going to be on or expressed when those genes are needed, and recall that those genes in the lack opera lack Z like y and like a there needed to metabolize lactose and break it down in order to get energy from it. However, if lactose is absent, if there is no lactose in the environment, and that means that those genes in the lack opera are not really needed because there's no lactose for those genes to break down. And so we can imagine that this means that the lack of operas would be off or inactive in the absence of lactose. And that's exactly what we're going to see here. And so when lactose is not available to metabolize because it's not available in the environment, then the repressor protein lack. I is going to repress the expression of the genes in the lack opera and so lack I this repressor protein it's going to bind to the lack operator and block RNA preliminaries, which recalls the enzyme that is responsible for transcription. Uh, and so it's going to block RNA preliminaries and prevent RNA polymerase from initiating transcription. And so there will be no transcription because it is being blocked and inhibited. And so if we take a look at our image down below, we can get a better understanding of the lack opera in the absence of lactose. And so, in the absence of lactose, the repressor protein lack, I is going to be active. And because it's active, it's going to bind to the operator and block transcription, preventing transcription and turning off the opera in the absence of lactose. And so here, taking a look at this image again, we're focusing on the lack opera in the absence in the absence of lactose, so there's no lactose available in the environment. And so, taking a look here at our image noticed we've got our lack opera on over here, and we've got the lack regulatory gene over here, which has the lack I gene with its own promoter and, of course, the lack I gene with its own promoter. It is going to be transcribed and translated. And in the absence of lactose, uh, the lack I repressor protein is going to be active. So here we have an active lack repressor, And so because it is a repressor and it is active, it is going to bind to the operator here, and so you can see that the active lack I repressor is binding to the operator. And when it binds to the lack operator, as we mentioned up above in the text, it's going to block RNA preliminaries and prevent RNA preliminaries from binding and initiating transcription. And so transcription of these genes is not going to occur because, uh, the lack I repressor is bound and blocking. Um, the RNA preliminaries in the absence of lactose. And this is a good thing for the cell, because when there is no lactose available when the lactose is absent, then the cell has no need to express these genes because these jeans are all involved with breaking down lactose. But there is no lactose, so it's not going to waste energy in producing the products of these genes. And so this is why, in the absence of lactose, the lack opera is off or inactive and will not be expressed. And so this year concludes our introduction to what happens when the black operation is in the absence of lactose, and as we move forward, we'll be able to talk about the lack opera in the presence of lactose, So I'll see you all in that video.