In this video, we're going to begin our lesson on ATP. Now recall from our previous lesson videos that ATP is really just an abbreviation for a molecule called adenosine triphosphate, where the 'a' in ATP is for the 'a' in adenosine, the 't' in ATP is for the 't' in tri, and the 'p' in ATP is for the 'p' in phosphate. And so Adenosine Triphosphate, or ATP, is a high-energy molecule that's used to power cellular activities. If the cell has a lot of ATP, then the cell has a lot of energy. But if the cell has a little bit of ATP, then the cell only has a little bit of energy. There are only three primary components of an ATP molecule. As its name implies with the triphosphate part, 'tri' meaning three, there are a chain of three phosphate groups in an ATP molecule. The adenosine part of ATP is referring to a molecule that actually has two components: a pentose sugar and an adenine nitrogenous base. Let's take a look at our image down below over here on the left-hand side to get a better understanding of the three components of adenosine triphosphate or ATP. The triphosphate part is referring to a chain of three phosphate groups that you see here 1, 2, and 3. We can go ahead and label these as phosphate groups, and there are, in fact, three phosphate groups on an ATP molecule. The adenosine portion of ATP is actually referring to both this sugar as well as this nitrogenous base. You can see that there is a pentose sugar here, which is this portion right here, and there's also a nitrogenous base right here, which is actually the nitrogenous base of adenine. Together, the adenine nitrogenous base and the pentose sugar here make up the adenosine portion of ATP. ATP is a high-energy molecule, but the way that cells extract the energy from ATP is through a process called ATP hydrolysis. ATP hydrolysis is the process of breaking bonds between phosphate groups in an ATP molecule that ends up generating chemical energy that can be used by the cell as well as ADP, or adenosine diphosphate, where the 'd' here stands for 'di,' meaning that it only has two phosphate groups. In some scenarios, ADP can also be hydrolyzed to form AMP, and the 'm' here is referring to 'mono,' adenosine monophosphate, and 'mono' is a prefix that means just one phosphate. Let's take a look at our image down below over here on the right-hand side to get a better understanding of ATP and ADP hydrolysis. Notice that at the very top here, we're starting with an ATP molecule. This is another representation of the base and the nitrogenous base and the pentose sugar represented right here in green. Then the three phosphate groups are right here, 1, 2, and 3. We can also represent ATP by this symbol right here, and we'll be doing that a lot throughout the rest of our course, representing ATP as just this symbol right here. If we take ATP and hydrolyze it, 'hydro' is the prefix for water, 'lysis' is the prefix for breaking down. Using water to break down ATP, you can see that water can be used to break the bonds between phosphate groups, the process of breaking the bonds between phosphate groups. When we break off this bond right here between the phosphate group using water, ultimately, what we end up getting is one of the phosphate groups is released and also energy is released. That energy can be used to power other chemical reactions and used to power other cellular activities. The molecule that remains only has two phosphate groups here, and so this molecule is now ADP, since the 'd' here stands for diphosphate. 'Di' is a root that means only two phosphates, one right here and the other one right there. The third one is released or attached to some other molecule, and in the process, a lot of energy is released. Again, in some scenarios, ADP, this molecule here, can also be hydrolyzed, releasing, as you can see the water here coming in to break this bond and that will release the phosphate group and also release energy as well. The AMP molecule is going to be made here. Again, the 'M' in AMP is for mono, and mono means only one phosphate group. You can see how the hydrolysis here is going to lead to the release of energy, and the release of energy is really what's going to be used to power chemical reactions. This here concludes our brief introduction to ATP, and we'll be able to get some more practice applying these concepts and learning more about ATP as we move forward in our course. So I'll see you all in our next video.