The Lac Operon

by Jason Amores Sumpter
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in this video, we're going to begin our lesson on the lack opera. And so the lack opera is actually an induce a ble opera, which means that it is normally turned off, but it can be turned on or it can be induced. And that's why it's called an induced herbal opera. And it actually has three different genes that encode enzymes that are responsible for metabolizing lactose for energy. And so lactose is a sugar. It is a carbohydrate that can serve as an energy source. But before lactose can serve as an energy source, it requires these specific enzymes to be expressed, and these enzymes again are going to metabolize lactose for energy. Now you can see that the lack Oberon gets its name lack because it's important for metabolizing lactose. And so the lack and lactose is the lack and lack opera. Now, these three genes that are encoded within the lack opera include number one lack Z number two lack Y and number three lack A. And so each of these genes, like Z like wine like A and code an enzyme, and those enzymes are all related to one another because they're all important for metabolizing lactose for energy. And so if we take a look at our image down below, which you'll notice is over here on the right, we're showing you the lack opera and again recall operations are a group or a set of related genes, all controlled by a single promoters, so you can see the lack promoters over here and also notice that there is the lack operator right here, and so lack Z lack y and lack A are the three genes that are in the lack opera and are all related to lactose metabolism. And so these three genes lacks the lack y and like they would need to be transcribed into an M R N a and then translated into their appropriate enzymes their appropriate proteins before, uh, they can be used to metabolize lactose. However, what's really important to remember is that transcription and translation actually requires a lot of energy, and so the cell does not want to waste energy and so, therefore, sells only want to express lack opera in jeans when those genes are needed. However, if those genes are not needed, then the cell does not want to be performing transcription and translation because it requires a lot of energy. And so basically what this means is that the lack opera on needs to be under regulatory control, where it needs to be able to be turned off and turned on under the right conditions when these genes are needed and when they're not needed. And so it's important to note is that there is going to be a repressor protein with this lack opera, and the active repressor protein is referred to as lack I mhm and so lack I is the active repressor protein and, uh, normally lack. I is going to be in its active state. And so the active repressor protein lack. I is going to repress transcription as a repressor protein should. And so normally the active repressor lack. I is going to repress transcription, and that is why the lack opera is normally going to be turned off. And, of course, the lack I active repressor protein is going to bind or be bound to the lack operator. And so if we take a look at our image down below, which will notice is over here on the left hand side, we're showing you the lack regulatory gene. And so here we have the lack hygiene and the lack. I gene has its own promoter, and so the lack I gene will be transcribed and translated into an active lack repressor, which is a repressor protein. And so this active lack repressor is going to bind to the lack operator right here and when it's bound to the lack operator as repressor proteins. Should they repress transcription, they block transcription. They prevent the RNA preliminaries from proceeding forward and transcribing these jeans. And so under normal conditions. This is what we tend to see is that the active lack repressor is made, and the active lack repressor blocks transcription of these genes. So this opera and the lack opera is normally turned off. However, under the right conditions, the lack opera and can be turned on it can be induced. And that is why we call it an induced herbal opera in because it's normally off. But it can be turned on, it can be induced, and so it's only going to the lack. Opera is only going to be transcribed only in the presence of lactose number one, but also in the absence of glucose. And so these are two ideas. The presence and absence of lactose and the presence and absence of glucose that we're going to look at these two ideas, these two scenarios and determine how is it that it impacts lack operation transcription. But what's important to note here is that the lack opera and will only be turned on and the presence of lactose and in the absence of glucose. And we'll talk about why that is, as we move forward in our course. And so the lack, opera and recall black operations and operations in general are associated with pro carry Arctic organisms and E. Coli. Escherichia coli is a bacteria, uh, and so the lack opera and E. Coli is how this lack opera was first discovered. And so that is the context that we're going to be looking at, the lack opera in and so the lack opera on an E. Coli. It contains a single promoter, the lack promoter and three genes required for lactose metabolism. And those three genes are like Z like y and lack. And so this here concludes our brief introduction to the lack opera, and once again, as we move forward in our course. We're going to continue to talk about the lack opera and how it works, so I'll see you all in our next video.