In this chapter, we focused on the regulation of gene expression in bacteria. Along the way, we found many opportunities to consider the methods and reasoning by which much of this information was acquired. From the explanations given in the chapter, what answers would you propose to the following fundamental questions? How do we know that the lac repressor is a protein?

Video transcript

Hi everyone. Here's our next problem. It says a protein called the blank suppresses the transcription of the LAC opera on. So let's recall that our lack opera is an induce a ble opera on its default position is off. And the protein that suppresses its translation that keeps it turned off is choice be the lac repressor. And that should be a pretty simple one for us because we call that a per oppressor is specifically something that prevents um a gene from being expressed. So that would lead us right to the lack of professor. Even if we didn't remember it off the top of our head, let's notice that we have a choice D. Which is both B. And C. So let's look at choice C. Next choice C says RNA polymerase. Well RNA polymerase does not suppress transcription. RNA polymerase is what does the transcribing? So that's not our correct answer. And then choice A. Is so we no choice D. Is wrong since C. Is wrong. And the choice A. Is cap. That's a metabolite activator protein and cap is the activator of the lac opteron. When cap is bound to its binding site it promotes the binding of RNA polymerase to the to the promoter. And if that pressure is gone it will turn up the transcription of the black jeans to a high level. So it's not a suppressor, it's an activator so it's not a correct answer. So this was a nice simple one for us. The protein called the choice be laC repressor suppresses the transcription of the black opera on you in the next video