What properties demonstrate that the lac repressor is a protein? Describe the evidence that it indeed serves as a repressor within the operon system.

Video transcript

Hi everyone. Let's take a look at this practice problem together. How does lac repressor inhibit the transcription of lack opteron and the lack opteron recall is responsible for lactose metabolism in certain bacteria. Now, a repressor is a protein and this protein binds D. N. A. And it literally blocks the necessary components for transcription. So it stops those components from being able to bind or work on the D. N. A. And transcribed genes. So let's review our options. We've got a. It removes the RNA preliminaries. Remember the lack of repressor blocks things it's not removing and therefore A. Is not correct. Let's take a look at be. It removes the basal transcription factors. Again the laC repressor will bind and block D. N. A. From being transcribed. It's not removing anything and therefore B. Is also wrong. Now we're going to take a look at D. It binds to a non coding sequence in the five prime end. Now if the lac repressor was bound to D. N. A. In a non coding sequence, it wouldn't block the operation transcription because recall a non coding sequence does not produce genes or amino acids and so D. Is also incorrect. So the correct answer is going to be. See it binds to the operator and recall that the operator is a part of D. N. A. That allows the necessary proteins needed for transcription to be able to bind like RNA preliminaries. So if the lac repressor binds the operator, it's going to inhibit RNA preliminaries. Therefore it will inhibit transcription. Alright, everyone. I hope you found this helpful and I'll see you soon for the next practice problem.