The Trp Operon

in this video, we're going to begin our lesson on the trip opera. And so trip to fan is an amino acid and recall that amino acids are the monomers, or the building blocks of proteins. And so trip to fan is an amino acid whose three letter code or three letter abbreviation is T R P or trip. And so trip to fan is an amino acid and trip to fan itself can either be absorbed by the cell from the surrounding environment or taken in from the surrounding environment. Or a trip to fame can be synthesized from scratch by the cell. Now the trip opera is a repressive ble opera, which, recall from our previous lesson videos, means that the trip opera is usually on or active, but it can be turned off, meaning that it can be repressed. And that's why it's called a repressive ble opera. And so the trip operas is a repressive ble opera and with five genes, and these five genes are all related to each other because they encode enzymes that are required for synthesizing trip to fan from scratch. And so the trip opera is responsible for, uh, encoding enzymes required for synthesizing trip to fan from scratch. Now, if we take a look at our image down below, notice that we're showing you an image of the trip operas, which has these five genes trip E, D, C, B and A. And, uh, these five genes are important for encoding enzymes for synthesizing, trip to fan from scratch. And so, of course, the trip opera has a trip operator where the regulatory protein will bind. And it also has a trip promoter as well. Where the RNA preliminaries will bind now, taking a look over on the left hand side notice that there is a trip regulatory gene, which is trip are, and so trip are is the regulatory gene that is going to encode the trip repressor protein and the trip repressor protein is going to be a repressor, and so that means that it will bind to the operator and inactivate transcription. It will repress transcription. However, the trip repressor protein is actually expressed in the inactive form, which means that when it is initially expressed, it is inactive and it will not bind to the operator. The inactive trip are repressor protein requires a co repressor an order for it to become active and bind to the operator to repress transcription. And so the co repressor for the inactive trip are is usually going to be trip to fan itself. And so when trip to Fan this co repressor is bound to the inactive trip, are it activates, Trip are and allows trip are to bind to the operator, and when it's bound to the operator, it can repress transcription. And so if we take a look at our image down below, we can get a better understanding of this here. And so the trip opera again contains five genes required for synthesizing trip to fan for trip to fancy synthesis, and it is regulated by the trip repressor. And so over here we have our trip regulatory gene, where you can see the trip repressor gene trip our gene, and it has its own promoter here, so it will be transcribed and translated into the repressor protein. However, when the trip are is expressed, its expressed in the inactive form and so notice we have the inactive trip Repressor and the inactive Trip repressor on its own, it cannot bind to the operator first, the inactive trip. Repressor needs to be bound by a co repressor, and the co repressor is usually trip to fan itself. So trip to fan can bind to the inactive trip repressor to form an active trip Repressor and the active trip repressor with trip to fan bound can bind to the operator and repress and block transcription of the trip opera jeans. And so, basically, what we're seeing here is that, uh, the trip opera, uh, is going to be, uh, repressed in the presence of trip to fan. When trip to Fan is available and present, it can serve as a co repressor to activate the trip repressor, and that will block transcription. And so this year concludes our brief introduction to the trip operas. But as we move forward in our course, we're going to take a closer look at the trip opera in the presence and in the absence of trip to fan itself. And so I'll see you all in our next video

in this video, we're going to talk about the trip operations specifically in the presence of tryptophan. And so when tryptophan, this amino acid is really, really abundant and prevalent and found in high levels in the environment, then the cell does not really have a need to synthesize its own tryptophan. And so the trip Oberon which has genes for synthesizing its own tryptophan, it's going to be inactive when there is plenty of tryptophan that is abundant in the environment. And so what happens is tryptophan is going to act as a co repressor to the repressor protein. And so the co repressor tryptophan is going to bind to and activate the Trip repressor protein. And so if we take a look at our image down below, we can see that cellular tryptophan is going to co repress the trip operation when it's readily abundant for the cell. And so we're specifically looking at the trip Operandi in the presence of tryptophan. And so when tryptophan is really, really abundant and prevalent, then the cell has no need to synthesize its own tryptophan. And so it needs to shut down the trip opera. And so this is how it works. The trip regulatory gene which encodes Trip our which is our suppressor protein which has its own promoter, it's going to be transcribed and translated into an inactive trip repressor. And the inactive trip repressor is only going to be activated in the presence of tryptophan. And so when tryptophan is really really, really abundant, then there's going to be tryptophan available to bind to the inactive trip repressor and the tryptophan is going to act as the co repressor here. So the tryptophan is acting as the co repressor. And so the trip to fan co repressor is going to bind to the inactive trip our repressor. And that is going to form an active trip repressor and notice the active trip repressor is capable of binding to the trip operator. And when it's bound to the trip operator it's going to block and inhibit transcription, turning off the trip operandi. And so it's going to prevent the RNA polymerase from binding to the promoter and proceeding with transcription. And so basically what we're seeing here is again when the trip operation is in the presence of tryptophan. When tryptophan is readily available then the cell has no need to create its own tryptophan. And so it's going to shut down the trip operandi through this mechanism where tryptophan acts as a co repressor. And so this here concludes our brief introduction to what happens to the trip papa ran in the presence of tryptophan. And so moving forward we'll be able to talk about the trip operation in the absence of tryptophan. So I'll see you all in that video

in this video, we're going to continue to talk about the trip operas, but specifically in the absence of trip to fan. And so, in the absence of trip to fan, when trip to fan levels are really, really low, and trip to fan is not readily available in the environment for the cell to absorb, then the cell must be able to synthesize or build its own trip to fan. And so, of course, the cell is going to synthesize its own trip to fan by using the enzymes from the trip opera. And so, in the absence of trip to fan, when trip to fan levels are really, really low, and trip to fan is not readily available in the environment, then the trip operation is going to be active and turned on so that the cell can make its own trip to fan. And so when cellular trip to fan levels are really, really, really low, what happens is the trip are repressor protein is going to remain in active, and the reason that trip are remains inactive is because it's not going to have trip to fan, because the trip to fan is really, really low uh, to serve as a co repressor. And so if trip to fan cannot serve as a co repressor because it's levels are really, really low, then trip are is going to remain in its inactive state. That means that it will not be able to bind to the operator and block transcription. And so, if it's not able to block transcription, that is going to allow for transcription to proceed. And that's going to turn on the trip opera and allow the cell to synthesize its own trip to fan. And so let's take a look at this image down below to get a better understanding of how low cellular trip to fan levels results in increased transcription of the trip opera. And so we're focusing specifically on the trip opera in the absence of trip to Fan, when no trip to fan is available. And so notice that in this image again, we've got our trip operandi over here on the right, and over here we have our trip Regulatory gene, which encodes for trip are this repressor protein. It has its own promoter, and of course, the trip are is going to be transcribed and translated. But when it's originally transcribed and translated, it's going to form the inactive trip Repressor and the inactive Trip. Repressor is not capable of binding to the trip operator without the co repressor, which is trip to fan itself. But if Trip to Fan is absent, then there's no co repressor to bind to the trip repressor. And so that means that the trip professor is going to remain inactive and because it remains inactive. This allows for RNA preliminaries to bind to the trip promoter and initiate transcription. Transcribing these jeans here into the messenger RNA, and then the messenger RNA will be translated into the proteins and again, these proteins. These enzymes are going to help create trip to fan. And so the cell will be able to make its own trip to fan when trip to fan is absent from the environment. And so this year concludes our brief introduction to what happens to the trip opera in the absence of trip to Fan, and we'll be able to get some practice applying the concepts that we've learned here as we move forward in our course. So I'll see you all in our next video