Models of Enzyme Action - Video Tutorials & Practice Problems

Models of Enzyme Action Concept 1

Now, we know that the substrate interacts with the active site of the enzyme. And with this idea, we need to understand that there are two models of enzyme action. Now, here we're gonna say the two models that describe how enzymes interact with substrates are are lock and key model. And then our induced fit model. So if we take a look at the lock and key model, we're gonna say here, the active site is rigid and unchanging. And we're gonna say here for this type of model, the substrate fits in like a key into a lock. And we know that a key is very specific for the type of lock that it goes into. Same thing here. When it comes to the enzyme and substrate interaction, here, we're gonna say that the active site is identical in shape to the substrate. So here we take a look at this example, we have our substrate and then we have the active site of the enzyme. The substrate is approaching it, the substrate matches the grooves the overall shape of the active site of the enzyme perfectly. So that when it comes in, it locks in exactly as it's supposed to. Now, the induced fit model is another way of looking at what could happen between an enzyme and a substrate. Here, we're going to say that the act um this is the induced fit. The active sight is flexible and changes and we're gonna say that it changes shape to accommodate the substrate. We're gonna say the active site resembles the substrate. It's not an identical match to the substrate, it just, it resembles it. It's in the ballpark. And we're gonna say this is a more accurate model of enzyme action. We don't typically get a lock and key model. When it comes between a enzyme and a substrate, they don't match up perfectly. What happens is here, we have our enzyme and here we have our substrate, we can see that the grooves of the active site of the enzyme don't match up perfectly with the grooves of this substrate. But it's OK because the substrate comes in and goes into the active site of the enzyme and the enzyme changes shape to accommodate this incoming substrate. So here we're gonna say we're gonna have a change in shape of the active site. And in this way, we still are able to obtain our complex, our enzyme substrate complex. So just remember these are the two different models in which an enzyme and a substrate can interact with one another.

Models of Enzyme Action Example 1

Which correctly describes the lock and key model. A enzyme undergoes a change in shape to accommodate the substrate at the active site. No, in a lock and key model, the substrate and the active site of the enzyme need to be identical in terms of shape. So this wouldn't happen next. The enzyme irreversibly binds to the substrate to form products. Now, here it doesn't matter which of the two models we follow. This is not gonna happen. It can't be irreversibly binding. Remember, it needs to be a non covalent bond between the substrate and the active site of the enzyme. In that way, the substrate can attach it transformed into products and then be released from the enzyme c active site of enzyme has a fixed shape that perfectly matches the shape of the substrate. This is true. This is the lock and key model. And then finally, d the enzyme is able to interact with many different substrates. Now, here in lock and key model, the active site and the substrate need to be perfect. They need to be identical to one another. This greatly limits the types of substrates and the variety of substrates that can attach. So this would not be true. You wouldn't be able to get many different substrates attaching. You need a more flexible shape in terms of the active site, which is not the lock and key model. So here option C would be our only answer.