This lesson will explain the structure and function of enzymes as well as describe the role they play in metabolism.

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Source: Video and Images Created by Amanda Soderlind

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In this lesson today we are going to discuss the structure and function of enzymes, as well as the role that they play in your body.

If you remember from earlier lessons, we discussed that ribosomes are part of a cell that make proteins, and that proteins can have various different roles in your body. And one of those roles is that they can become enzymes.

Enzymes are made up of proteins. Enzymes speed up chemical reactions in your body. So that's their function. An enzyme can actually make a chemical reaction happen millions of times faster than it would otherwise. They're very important in your body because it really does help to speed up those chemical reactions that are happening in your body all the time.

Enzymes are very specific to the type of reaction that it takes place in.

An example that I'm going to give you is salivary amylase. This is an example of one of the enzymes that you have in your body. The purpose of salivary amylase is to break down starches into sugars.

If you eat something that has a lot of starch in it, the salivary amylase in your saliva will begin to break down those starches into sugars in your mouth. Salivary amylase will only take part in that type of reaction. It will only break down starches into sugars. It's not going to take part in any other reaction in your body. So it's very specific to the type of reaction it participates in, as well is the type of substrate that it will break down. And we'll discuss in just a minute what a substrate is, but for example, salivary amylase will only work on starches. So salivary amylase is not going to take part in any other type of reaction, except for this type of reaction here.

Enzymes can join substances together, or break them apart. So sometimes they're breaking down substances into smaller substances, such as the example with salivary amylase. It's taking a complex carbohydrate and breaking it down into a more simple carbohydrate.

But sometimes enzymes can also join substances together into a larger compound.

Let's take a look at the diagram that we have on the bottom here. We're going to pretend that this purple part here is going to represent our enzyme. And these green parts are going to represent our substrates.

A substrate is whatever the enzyme is working on to either join together or break down.

And this area right in here is called our active site. The active site is the part on the enzyme where the substrates will attach.

These are the three main parts that you'll need to know about an enzyme. So substrates will attach to an enzyme at the active site.

Our next step from there, it will look something like this. We have are substrates that are now attached to our active site of the enzyme. From there, the enzyme well either break those substance down or join them together.

In this case, we started with our two substrates that were apart, and our enzyme actually put them together. This is what we call our product. It's our end result. What we have after the enzyme has done its job.

One thing I want to mention is that an enzyme, after it participates in this type of reaction, is going to remain unchanged. So the enzyme can actually be used again. It's going to be the same at the end as it was at the beginning. It's unchanged after the reaction. So our substrate has changed and become a product. It's different in the beginning than it is in the end, but our enzyme will remain unchanged, and can be used again.

I want to go back to the stage just briefly, for one second, too. You can't tell this because my artistic skills are not fantastic, but what will happen in this stage, when we have our substrate attach to our enzyme, is that the enzyme generally will kind of mold itself around our substrate. And we call that induced fit. And what that does is puts pressure on the bonds of the substrate, in order to produce that product. So it's putting that pressure on the bonds, and either bonding those substrates together, or helping to break the bonds and break that substrate apart into two separate products.

This lesson has been a brief overview on the structure, function, and role of enzymes in our body.

  • Enzyme

    A protein that changes the shape of a substrate in order to increase the speed of chemical reactions

  • Substrate

    The molecule that is acted on by an enzyme

  • Product

    The result of a chemical reaction where an enzyme has acted on a substrate

  • Active Site

    The area on an enzyme where the substrate attaches