Evaluate these statements about regulation of the lac operon. Select True or False for each statement.
T/F The lac operon is transcribed at the highest rate when extracellular glucose and lactose are abundant.
T/F The repressor protein is bound to DNA of the operator when lactose is present.
T/F A mutation in the operator is likely to prevent transcription of the lac operon under any condition.
T/F A mutation that alters the catabolite activator protein is predicted to alter the regulation of many different operons.

Question

Evaluate these statements about regulation of the lac operon. Select True or False for each statement.
T/F The lac operon is transcribed at the highest rate when extracellular glucose and lactose are abundant.
T/F The repressor protein is bound to DNA of the operator when lactose is present.
T/F A mutation in the operator is likely to prevent transcription of the lac operon under any condition.
T/F A mutation that alters the catabolite activator protein is predicted to alter the regulation of many different operons.

Accepted Answer

Welcome back. Let's look at the next question. Cells express lacrosse bronze only when needed. Because well black operations um control the production of the enzymes that digest lactose as we recall from our content videos and they're only expressed in the absence of glucose. And then of course the presence black tose. This is because first of all, glucose is uh takes less energy to metabolize. It's just a single ring sugar. Um As opposed to practice where you have to hide relies um the bond to break it down into its two component sugars. But also because just the transcription and translation itself of those genes that digest lactose. That process requires a lot of energy. So you don't want to sell to have to go through that whole process if it's not necessary for the cell to metabolize glucose at that time. So when we look at our answer choices, we see that choice B says transcription and translation require a lot of energy. So the cell has developed this opera in which is induce a Ble so the operations mostly in the off position. Um So that the cell doesn't go through all that energy usage to provide something that isn't necessary and just turns it on when it's needed. Let's be thorough and just look at the other answer choices. Choice A says its products are toxic to the cell. Well that's not correct. Choice C says the genes involved are rare, know the genes are there. They're just turned off by the presence of a repressor protein. Choice D says the repressor protein is difficult to produce. Well that's not the case. So again, our answer here, cells expressed lack up runs only when needed because Choice B, transcription and translation require a lot of energy. See you in the next video.

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Key Concepts

Lac Operon Structure and Function

Repressor Protein and Induction

Catabolite Activator Protein (CAP) and Positive Regulation