Which statement is false about allosteric regulation?

Question

A. It is usually the mode of regulation for the last step in reaction pathways since this step produces the final product.

B. Cellular response is faster with allosteric control than by controlling enzyme concentration in the cell.

C. The regulation usually is important to the conversation of energy and materials in cells.

D. Allosteric modulators bind non-covalently at sites other than the active site and induce conformational changes.

Answer 1

Hello!

I decided to add this question to discuss the role of allosteric regulators in enzyme regulation.

The first step in answering this question is to review what we know about allosteric regulation.

1. In scientific speak, in allosteric regulation, an "effector" molecule binds to a site other than the enzyme's active site and induces conformational changes. So there is an active site, where activity happens, and the allosteric site attaches to the enzyme at a different site than the active site. It induces conformational changes, which means it changes the shape of the enzyme. This changes how it can bind to the substrate.
2. In simpler terms, the active site is like a front door and the enzyme is like a building where we're making a product. The allosteric site is like a back door, a different way of getting in. Breaking into the back door changes the shape of the building and makes it easier or harder to get the job done, depending on what the allosteric regulator is there to do.

The question asks which option is false.

1. Well, D talks about the allosteric regulator using a back door to change the shape of the enzyme, which is true.
2. C talks about saving energy. If we turn off the enzyme or make it not work as well, it's not using as much energy. If we make the enzyme work faster, it doesn't need as many materials because we're making it go faster by building the product in a different way. C is true.
3. B is trickier. Is allosteric regulation faster than controlling enzyme concentration? Yes. Controlling enzyme concentration is like gathering your building blocks. Allosteric regulation is like breaking in and working using a different way of building the product, so we save time we would have used getting the building blocks. So B is true.

The one answer left is A. This must be the false answer. We can see if it is false because it talks about the last step in a reaction. Allosteric regulation is unrelated to the last step in a reaction! Allosteric regulation gets the process going or slows it down, but this can be at any step in the reaction! Thus, A is false, but here it is the correct answer!