 Okay, let's do a walkthrough of this animation and then we will cha-ching this lecture off our list. So this is really similar to the cellular respiration animation and what you'll notice is that I have color-coded it yet again. This is a chloroplast. These are grana and each one of these is a thylakoid. So remember, if you just color-code yourself, you'll see that this is the thylakoid space. This is actually the stroma. Last time it was the cytoplasm. This time it's the stroma of the chloroplast itself. I kind of, yeah, we'll just go from there. Okay, so I'm going to take a little slice of a thylakoid. You can label all the parts to practice, which is phenomenal. Way to go. I'm going to go into rock stars. And now let's start out doing the light reactions. Remember that, oh look, I've got them all drawn in. We have photosystem two. We have a little electron transport chain. We have ATP synthase. Photosystem one and then the same thing, an electron transport chain. I want you to think back and remember where are all of our electrons going to come from. Notice that I have electrons in the reaction centers in each one of these photosystems because we're just going to send down some light energy. Look, I've got little photons rolling down the trampoline hill and energizing my electrons. How money is that? And then they get flung up because they have so much energy. That's awesome. Notice we've got a big old hole here. We're going to have to replace those electrons. Be thinking, how are you going to replace those things? We now have high energy electrons thanks to the sun. In cellular respiration, we get the high energy electrons from glucose but the sun provides the energy to make these things high energy. And then we pass them along to the electron transport chain which we're going to use the energy and we pass them down this chain. We're going to use that energy to pump protons. Wow, that was magic, wasn't it? Rather than pump them one at a time because we've already done that. You've already pumped protons. You know how an electron transport chain works. So now it's just magic and we show them all up here. We know that the energy to do that comes from passing these electrons down the chain. Where are the electrons going to go? Well, what we can know is that we've got to put them somewhere. They're hanging out right here and we've got to send them somewhere. First of all, let's illustrate the fact that we have an ATP synthase in this whole mission and the ATP synthase is going to use the proton gradient to produce ATP. Awesome. What are we going to do with that ATP? Let's take that to the light reactions. Oh, we missed the whole energy. Look. I'm pointing on my screen and you can't see that. Look. Electrons, sunshine. Same thing. Totally cool. Pow! Popped up there. Those awesome little electrons. Now we're going to pass them down, pump some protons into the space. Now we need an electron acceptor because we've got to get rid of them somehow or else we're going to have a log jam. So, yeah, we already know that these are our problems. I actually wrote down the words. That's craziness. Well, let's look at what the problems say. Who's the final electron acceptor for photosystem one? You know the answer to that, don't you? It's the high energy electron carrier. So, do we replace the electrons lost by photosystem one? You know that too. Get them from photosystem two. Who's the final electron acceptor for the electron transport chain in photosystem two? We just answered that one with number two. Give it to photosystem one. He'll eat anything. How can we replace the electrons lost by photosystem two? Why am I even going to answer that one because I know I've got a cool animation for that. Who's the final electron acceptor for photosystem one? Here comes the high energy electron carrier. Where's it going to take those? Where's this guy going to take them? To the Kelvin cycle reactions. Okay, so now let's replace the electrons lost by photosystem one. Where are they going to come from? They're coming from photosystem two. That's a perfect deal. That's a perfect solution. Yep, and now who's going to be the final electron acceptor for photosystem two? We already know that as well. That's photosystem one. All right, and finally, how are we going to replace these electrons here? We're almost perfect. We've almost got this under control. Remember, water comes in and does exactly the opposite of cellular respiration. It splits. And now we have a couple of extra electrons, some protons, and some oxygen. And that process, now we're back to the start and we're going to redo this whole thing. I kind of think that's the end of the story. Those guys go to the Kelvin cycle. That makes perfect sense. That is the end of the story. And what's going to happen with the oxygen? I'm going to breathe it. Thank you very much. It's been a lovely lecture. I hope you enjoyed talking to you right now. And I will see you later, dearies. Bye-bye.