 Photosystem 1 is going to solve some of the problems that we came up with in Photosystem 2. Look, Photosystem 1. Now I'm going to make everything else a little bit smaller in order to fit it. Remember, they're just embedded in the thylakoid membrane in that space. What do you think? Okay, it's a photosystem. So we're going to have electrons. It's actually going to gather. I'm going to draw another sunshine here so that you can see that, yeah, we've got sunlight is coming down even though it makes no sense, but sunlight is going to come down and electrify those electrons. That photosystem 1 is going to do exactly the same thing and gather in that light energy and use it to produce high-energy electrons. Bo-bo-bo-boing. Bo-bo-bo-boing. Okay? So it's going to lose electrons, too. What's going to happen? Where do its electrons come from and who's going to be my final electron acceptor? Did you follow any of that? Dude, this is perfect. Let's take the electrons from photosystem 2. We've got to give them to someone. Let's give them to photosystem 1. Photosystem 1, through its own electrons up there, it's going to need to have its electrons replaced. This is a win-win situation. Photosystem 2 has a final electron acceptor. Photosystem 1 has a way to replace its electrons. Win-win-win-win. We'll have the issue of how are we going to replace the electrons in photosystem 2, and we're going to come to that. Exact same function here, folks. We have more electron, the proteins that pass those high-energy electrons around, and we're still going to need another electron acceptor. And guess who is my final electron acceptor in this scenario? You're not going to believe this. It is a high-energy electron carrier. What? True story. So we actually get a high-energy electron carrier that this guy is going to head off to the next stage. So you may remember, I don't even know if I told you, but I did. It's headed off to the Calvin cycle. That's a high-energy electron carrier. So now we've actually got a final electron acceptor for photosystem 1. These guys are still doing exactly the same thing. They're pumping protons in. These protons are creating the concentration gradient that's producing the ATP that's handy. The ATP is going to be needed in the Calvin cycle also. So we've got two final electron carriers. We still don't know what's going on with photosystem 2. Where do these electrons come? How can we replace these electrons that get passed along? It's related to, look, if you take a water molecule, this is backwards of cellular respiration. If you take a water molecule and split it, it can produce oxygen and a couple of hydrogens. Oops, those guys were pink. And some extra electrons. So my electrons in photosystem 2 are going to be replaced by water. It's beautiful. I mean, doesn't that make perfect sense to you right there? I've got it right now and, wow, my eyes are kind of crossing. That's okay, though. We're going to head to the Calvin cycle. And then we're going to talk about why we even care. And then I have an animation of photosynthesis where we can look at this whole process in sequence and have it be a little bit cleaner than this image. So let's go look at what happens in the Calvin cycle.