And that shape dictates what the function of that protein is. And so by changing the arrangement of our amino acids, we we can basically create a different protein with a different type of function. Now, in addition to increase the functionality and the diversity of the functionality of our proteins, we can basically modify the proteins by modifying the amino acids. And there are five common ways by which our cells modify amino acids, as we'll see in just a moment. Actually, there are many more ways, but we're going to focus on these five in this lecture. So we can modify amino acids by adding acetal groups, hydroxyl groups, carboxyl groups, sugar groups, phosphoryl groups, as well as many other different types of groups which we're going to discuss in future lectures.