11) Mutation that occur in the regulatory gene of repressible operon in E. coli cells woul result in? A- Continuous transcription of the gene B- Complete inhibition...

A mutation that inactivates the repressor gene of the lac operon results in (a) the continuous transcription of the structural genes (b) no transcription of the structural genes (c) the binding of the repressor to the operator (d) no production of RNA polymerase (e) no difference in the rate of transcription

Everybody today we're talking about what would happen if Opteron repress Er, um was mutated in such a way that it could not find the operator so trying to figure out what happens. Okay, so we have a few options. We have four. So let's write down a, B, C and D and go through why they don't work or which one works and why they don't work the ones that don't want to call. Okay, I'll use blue to cross mount once we go through them. So number one, I mean option A, we have is irreversible, binding on their oppressor. To the promoter, um, the binding or permits of the repress or to the promoter is definitely reversible because relative duration states that each state depends on the number of active professor in the molecule of ground. So if there isn't any active ones can't be true services brown well moving on to be which is, and the transfer that basically, um, you'll have reduced transcription of the operators seems specifically so. This isn't true because, um, if the transcription of the opera on jeans resumes in the cell trip to fan drops so that the repressor oven induce herbal Opteron was mutated. There would be no actual effect at the transcription genes. So we know that can't be true. Moving on to see which is that the build up of the substrate from pathway controlled of the by the opera? Um, the build out of the substrate buildup of substrate for the pathway controlled by the operation on, um, can't occur if their oppressor or oven induce a ble operations mutated. Eso that can't be true now living on 60 for stuff person. Okay, okay. Moving on with the D If their oppressor oven induce a ble Opteron was mutated. It occurred. Um, if it occurred, this would great continuous transcription of the operations jeans. This is true because it wouldn't be repressed. D is correct. Good. Todo So I hope that helps you understand.

So we want to know that if their oppressor and the systems such as the lock opera on system were mutated so that it could no longer bind to the operator. So remember that the black op around system is basically it's an induced herbal operating system. If, ah, if a molecule that interacts with the repress ER is present, then it will make sure that the repressors off of the DNA. So if we were to look at it here, we can see that we've got our protein, which is our lacquer oppressor. Um, and normally that's going to be bound to the DNA. And when it's found, two DNA aren't a plum. Race isn't going to be able to function, however, when Allah lactose binds to the protein, the protein is no longer able to fit in that same spot, and so it's no longer bound to the opera on and are in A is able to be transcribed freely. So you can see that if there was a mutation that prevented this repressor from ever binding two thie from ever binding, too the operator, then we would have Arnie would simply have a free range to continuously go and go and go and promote these enzymes. So if we look at her ah question and see what would happen one. Ah question. They says that, um, option A says that expression of the operas genes would be reduced. Well, Clearly, it wouldn't be reduced. Arne is going to be able to constituent of Lee, go through and allow for the expression of those jeans. B says that their oppressor would be permanently bound to the promoter again. It's not going to bind to the operator, which is part of the promoter, so, no, it would not be permanently bound to the promoter. Lactose buildup would occur well again. We're we're having thes enzymes that are used to break down lactose, and so are all of our lactose is going to be used up, so that would not be occurring, either. Now, the lactose enzymes those would be continuously expressed because there's nothing that's going to be preventing them from being expressed. Its going to just constituent Lee beyond, because there's nothing controlling are in a play. Marie's from going through and creating the irony for those enzymes

If each of these proteins were missing, what would happen during the DNA replication process? What do you need? A plan raises very useful because the unipolar makes replaces the primer. The already primary with DNA. And more importantly, it actually lays down the base pairs. So if it was missing, they would have to find their own way to lay down, um, than individual nucleotides for Indian A like a slight case, um, connects the two strands of DNA together, um, groups connects the oak Okazaki uh, fragments. Let's keep going. Um, we have sliding clap for D N A primaries. This allows the DNA polymerase from disassociating with the templates trend. Otherwise, you could simply disconnect, So it prevents memories from DNA primaries from disconnecting from from the template. Next we have the d is the nucleus that removes the irony primers. Well, this is very important because it can cleave the double stranded breaks in the target molecules, and this is very useful for DNA repair. Um, so it's kind of like the proof reading before the DNA. Well, one of the farms of proof reading, Um, and let's finally get t e. So e is the oldest one more. So this is a DNA helix case. Hilly case is a charge of end zipping the DNA at the beginning at the point of for application at the point off replication. So, um, if if it was missing, they would have to find a different way to unzip that DNA from double helix structure. And let's finally get to f f is primaries prime misleads down the Arnie primer, um, which allows for the DNA playmates to hop on. So if there was no our promise, the cell would have to find some other way that allows the d. N a plan may still hop on and start replication. So thank you for watching, and I hope this help.

This question asks an opera encoding G's that are transcribed and translated continuously to provide the cell with constant intermediate levels of the protein products is said to be which of the following we have irrepressible induce herbal constitutive and activated. So activated is not a ah term that we would necessarily use where at least we wouldn't use it by itself. So constant activated by itself would not be our answer and repressive ble wouldn't make sense because these genes that we are talking about are always active. So they're not being and induce. Herbal is also not what we're looking at because once again the genes in question are being continuously transcribed and translated, so they're not way. And if we think about what that means, basically we are saying that they are constitutive Lee activated, or that they are continuously transcribed and translated, so if they are constituted, then they are going to be kind of fundamental and they will always be on at a background level. And once again, this is intermediate level. So now we're not looking at full on extreme high concentrations of this enzyme being produced, but it would be constituted. The active mean that it would, uh, always be produced at a stir in level. So choice, see, is our correct answer.