Why are the genes involved in lactose metabolism considered to be...

Question

Why are the genes involved in lactose metabolism considered to be an operon?
a. They occupy adjacent locations on the E. coli chromosome.
b. They have a similar function.
c. They are all required for normal cell function.
d. They are all controlled by the same promoter.

Accepted Answer

Hi everyone. Here's our next question. The lack opteron is involved in lactose metabolism and bacteria. It is activated under which condition. So let's first think about we look at our four answer choices and we see they're all questions about the presence or absence of lactose and glucose. So why is the presence or absence of glucose significance here? That's because when glucose is present, bacteria will prefer it to lactose. That's because it takes fewer steps and less energy to metabolize. And that's because glucose is just a single ring sugar. Whereas lactose is a dime er you need to hide, realize the bond between it and break it down into its two components sugars before you can digest it. So when glucose is present you will not see the activation of the lack. Outrun. So let's eliminate our answer choices that involve glucose being present. So we see that Choice B says the abundance of glucose abundance of lactose and glucose. But as the abundance of glucose, the choice B is not correct. Choice C says in the absence of lactose in the presence of glucose. So choice C. Is not our answer. So Choice A and choice D both have an absence of glucose. So now let's think about the presence or absence of lactose. So when lactose is present, it's metabolized or I'm sorry not metabolizes. I summarize to a low lactose, allow lactose, then binds to the repressor protein. The lack opera is an induce a ble opera on meaning it's normal position is the off position. So when this ala lactose binds to the repressor protein. Oppressor protein is blocking the transcription of the genes in the laC opera. When a lactose binds to it, the repressor protein is released and the lack genes will be transcribed and this allows lactose metabolism by the bacteria. So again, when lactose is present, it gets I summarized to a low lactose which binds the repressor that's on the laC opera, causing the oppressor to be removed, allowing the transcription of those genes that will allow the metabolism of practice. So it's activated by the presence of lactose. So we see that choice A. Is the presence of lactose and absence of glucose. So that would be our correct choice here. Whereas Choice D. Which has an absence of lactose is not our correct answer. So the lack opera is activated under which condition that's choice A. The presence of lactose and the absence of glucose. Thanks for watching. Hope to see you in the next video

Why are the genes involved in lactose metabolism considered to be an operon? a. They occupy adjacent locations on the E. coli chromosome. b. They have a similar function. c. They are all required for normal cell function. d. They are all controlled by the same promoter.

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