 Okay, I'm going to introduce you to your new best friend, adenosine triphosphate. You do not have to know, you don't have to reproduce this picture. I'm going to break it down for you and we're going to make it diagrammatic, but I always find it interesting to actually be able to visualize the atoms that are involved. ATP, adenosine triphosphate is a nucleotide. So it's in the category of biomolecules of nucleic acids. And it consists of three parts. If we were going to break down the name of adenosine triphosphate, we have an adenosine piece, and I don't know if you remember this, but the nucleotide consists of a sugar, which is in this case, it's ribose. And a nitrogen base in this case is adenine. So that adenine plus ribose sugar makes a part of this molecule that we call adenosine. And then you tell me, what are we seeing in pink if the other part of the name is triphosphate? Well, we have three phosphate groups, phosphate ion groups that are connected to each other and then connected to the adenosine. Because I like seeing the detail to remind us that, okay, this is just a thing made of atoms, but I also like simplifying it so that we see the important parts. And I have this drawn in a more diagrammatic way so that you can see the important parts. And notice, there are a couple of things to notice here. We have three phosphate molecules. They are bound to each other with chemical bonds. Do you see the chemical bond here, here and here? And then we have our adenosine. The question that we're going to ask, these bonds are not the same. These chemical bonds are not the same as each other and the colors indicate that. So let's look at how this ATP molecule is gonna work. Our question that's gonna guide this process is how does ATP provide energy for cellular processes? A common question that you will see in biology tests is what is ATP? And often folks say, oh, it's the energy currency of the cell, it's like energy money. And our intention here is to go, well, how? How does it provide energy? Like, great, it's energy money, but how does it actually do that? And it has to do with breaking and forming bonds. So the thing that we're gonna look at is actually a chemical reaction between ATP and water. Is there any water in your cell? It's all water, you're like a bag of water. So everywhere that ATP is, it is basically surrounded by water. And I've illustrated that water here. Water combining with ATP, adenosine triphosphate, this is the reaction. It combines to form water with a phosphate attached and ADP, adenosine diphosphate. And I've drawn that all out here for you so you can see it. That's the reaction. Now, you should still be going, dude, this tells me nothing rigs. Where does the energy come from? And we're gonna have to answer another question in order to get here. Well, okay, we're gonna answer two questions. And it's energy related and we just talked about it. So this shouldn't be difficult. Question one, what happens when a chemical bond forms? And question two, what happens when a chemical bond breaks? What are the most important words in these questions? Like what are the key things that make these two questions different? Cause almost all the words are identical in the two questions. We're focusing in on chemical bonds forming and chemical bonds breaking. Maybe at this point you're like, I know the answer. I know the answer. Write it down, get it out there, answer those two questions. If you're still going like, wait a minute, what are we even talking about? These are your two options. When chemical bonds form and when chemical bonds break, there is some sort of energy consequence. One of them requires energy and one of them releases energy. Which one's which? Throw it in there. Are you ready for what I thought? When chemical bonds form, and here I am again with my magnets, when the chemical bonds form, energy is released. When the chemical bonds break, energy is required. That's huge, don't forget that. Now that we have that established, now we're gonna remind ourselves that we're breaking and forming chemical bonds around water and with this ATP molecule. So let's take a look at how we're gonna keep track. So I set up an energy scorecard. It's like a scoreboard for fun because I like games. And let's see what is going to win in this energy battle. We know that if we are going to release energy, a bond has to form. And we know that if we're going to break a bond, then that's gonna require energy. And then we're gonna add it up to see what the net outcome is. Some chemical reactions require energy. You have to put more energy in in order to make them happen. And then you will get out in the long run. And some are the opposite, some of them release a lot of energy. I bet you can anticipate that somehow this ATP situation is gonna somehow release energy so that we can use it for cell work. Okay, we're gonna break a chemical bond. The first thing that has to happen is we have to break one of the chemical bonds. And the one we're gonna break, it's called the terminal bond. It's the terminal phosphate bond. And I colored it yellow because it's different than the other ones. It's actually a really weak bond. It's unstable, which means it's really easy to break. If I break it, look, did you see that? Watch, I broke the bond. The bond is gone. Once that bond is gone, we have to decide how much energy did it take to break that bond? So let's throw a number in there. And I'm just, these are made-up numbers. This is a made-up scoreboard. I just threw the number five in there. We'll say it took five units of energy to break off that terminal bond. And then we get a net outcome. Overall, this whole system so far cost us five units of energy. So so far we put energy in. We haven't gotten any energy out. How are we gonna get energy out? We're gonna have to form a bond, right? Like that's the only way to get energy out of the system to release energy. We have to form some kind of chemical bond. We've already seen who we're gonna form the chemical bond with. Who do we form it with? Oh, you know it's true. We're getting closer. We're forming a bond between that phosphate and the water molecule. And watch. Whoa! That was a strong. It's like, this is the phosphate and this is the water and they're all the way across the room from each other. And even being all the way across the room from each other, they zoom. The magnets are so strong that they zoom together and a doodoo load of energy is released. If we captured that zooming and connecting we could get do a lot of work. We have to fit, look, I did finish. I went ahead and said, how much energy is that that was released? And I said, it's a hundred. Another completely made up number, but illustrates the fact that if we started with five to break that chemical bond, our net outcome, we got a hundred when we formed the new chemical bond and the outcome is definitely in the energy released category. We released 95 units of energy. Again, totally random numbers made up. Now, just as a little like thinking ahead, hopefully this illustrates for you how chemical bonds are related to energy use in cells. That little ADP and P attached to a water molecule, those guys are like Legos. And if we put energy in, right, we could pull that phosphate off of the water. It would require 95, oh, it would require a hundred units of energy to pull them apart, but we could break that bond and then stick it back onto the ADP. It would release five extra energies when we put that phosphate back onto the ADP. And that net reaction going the other direction is going to cost energy. Think about that for a minute, but super interesting and cool, we can reverse that reaction. It is possible, but the energy consequences are totally different. If we're using up ATP and turning it into ADP plus P, energy is released. In order to make more ATP, we're gonna have to pull that phosphate back off of the water molecule. That's gonna require energy to do and then rebuild our ATP molecule. If that feels like, what? Watch this again and know that we're gonna talk about ATP in the next two lectures. We're going to be producing it and seeing how it gets produced. Okay, so next up, we're gonna look at the big picture. ATP is one example of chemical energy. Now we're gonna look at the big picture of energy transfers on Earth, on our planet. But I have to find my stop button. Okay, bye.