IPTG is a molecule with a structure much like lactose. IPTG can be transported into cells by galactoside permease and can bind to the lac repressor protein. However, unlike lactose, IPTG is not broken down by ββ-galactosidase.
Predict what would occur to lac operon regulation if IPTG were added to E. coli growth medium containing no glucose or lactose.

Question

Predict what would occur to lac operon regulation if IPTG were added to E. coli growth medium containing no glucose or lactose.

Accepted Answer

Hi everyone. Let's look at our next question. It says how does I. P. T. G differ from lactose in terms of its interaction with the lack operations. Let's recall from our content video that the lack opera is an induce a ble opera. And this means therefore it needs a regulatory molecule to turn on gene expression. So when we look at I. P. T. G. Versus lactose and their interaction with this opera on. Well lactose when it enters the bacterial cell is quickly I summarize to Allal actus and allow lactose is the normal regulatory molecule that turns on the lack operation. However a little actress itself is broken down by one of the enzymes produced when the lack operations is induced and that enzyme is beta galactose oxidase. I. P. T. G mimics practice it is capable of binding to the lack professor and inducing gene expression. So just like al lactose it can turn on that lack Opera. However it is not broken down by those enzymes and this means it's level remains constant. The lactose, once it turns on that black opera on it gets broken down itself by the beta galactose sides. But I. P. T. G. It can be used to turn on but it's level remains constant as it's immune to being broken down by the bay to galactus itis that makes it useful in experiments where you want levels of reagents to remain constant. Um And you can induce the transcript expression of proteins um Where their expression is controlled by the lack opera. So let's look for answer. Choice is remembering that we want to see which choice tells us how I. P. T. G. Differs from lactose. So Choice A. Says it induces lack operation activity. Well this is true of both of these. So that is not our correct answer. Choice B says it cannot be hydrolyzed by the enzyme beta galactose IDs. Well, here we go. This is our difference between these two molecules because a lactose is digested by medical facilities while I P. T. G. Is not. Then we'll just look at the remaining two choices. Choice C says it leads the production of enzymes that can metabolize lactose. That's correct. Both turn on induce the lack opteron which then results in the production of those enzymes that metabolize lactose. So that's not a difference between them. And finally Choice D. It makes the genes controlled by the lac operator sequence be expressed abundantly. Well that again is similar to both of them since both of them uh turn on the lack chaperon. So that's not a difference between them and therefore not our answer. So how does I. P. T. G. Differ from lactose in terms of its interaction with black operations? Choice be it cannot be hydrolyzed by the enzyme beta galactose cities. See you in the next video

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Key Concepts

Lac Operon

IPTG and its Role

Galactoside Permease