 All right, here's the place where if you skipped out on the last on the illustration or the animation that we just did this part might need a little bit of refreshing. But if you didn't skip out on that animation, we emphasize the role that oxygen plays in the whole thing. The whole process will back up if we don't have oxygen as our final electron acceptor. I'm going to just go back to this and just add in oxygen is required. And I'm going to mess up this whole diagram, so just go with me here. If we don't have oxygen, the electron transport chain is going to back up. Do you agree with that? Because all of our electrons, if you don't agree with that, go watch that animation and it becomes very clear that those electrons, those proteins don't have anywhere to put their electrons. So if you don't have anywhere to put them, you hang on to them. And then a new high energy electron carrier shows up and it doesn't matter because there's nowhere to put your electrons. So the whole thing backs up. If you have too many loaded up high energy electron carriers, you don't have any empty cars for new electrons. So the entire thing, I'm going to show you the line of backup. The citric acid cycle backs up. The modification of pyruvate backs up. Glycolysis can take place. Nothing else is possible. And the only reason why glycolysis can take place is because if we don't have oxygen, pyruvate can be turned into something else. Now this is humans that this happens to. Pyruvate can be turned to lactic acid in the absence of oxygen. Let's put that down. No O2. You can shunt the pyruvate into lactic acid and that lactic acid is a super interesting molecule. I grew up as an athlete and was told my whole athletic career, the burn, the burn you feel, that's lactic acid. The soreness, the soreness that you have, that's lactic acid. I am not an expert in lactic acid and dude, we should have, that's a great idea. We should have a haps conference where somebody comes and gives us the scoop on lactic acid. Look, I just wrote it down so I can remember to get some professional development on lactic acid. Because I've heard that that is not true. Lactic acid can feed into different energy sources and you still get some energy. So from our glucose molecule we still get some ATP even in the absence of oxygen, but two ATPs compared to a total of 32? I mean that's why you want some oxygen. That is why. When you sprint, you can sprint, some people can sprint longer than others. I don't sprint for very long anymore. I used to run the 400 meters and would be completely dead at the end of that thing. It was a brutal race. But I felt like I was sprinting that entire time and it was, you know, over a minute, minute and four seconds. It would take me to run one full time around the track. And I was hating life at the end of that thing because I couldn't get in enough oxygen to provide the energy that my muscles needed to continue going that fast. As opposed to, I think people, when they see me jogging, they're like, dude, is she actually moving? My 75 year old mother can walk at my jogging pace. We'll go exercise together and I'll jog and she walks and that tells you how slow my jogging is. It also tells you how fit and amazing my mother is. That's cool. But when I'm jogging, I'm getting in as much oxygen as I need to fuel that exercise and that's aerobic exercise. I can keep going for as long as my muscles and my knees will approve, will handle it. I can keep going. So we can get energy without having that final electron acceptor, but not for very long. Like eventually we need oxygen because our energy needs exceed what can be provided to us just through the process of glycolysis. The other thing that I want to tell you here that I think is really cool is yeast. When yeast goes through cellular respiration without oxygen as a final electron acceptor, they do not produce pyruvate. They do produce pyruvate, sorry. They go through glycolysis, they produce pyruvate. If they have oxygen, they're going to send, they're going to do their yeast-ly cellular respiration and they're going to get all their energy out of it because they'll have oxygen as the final electron acceptor. Without oxygen, they shunt that pyruvate not into lactic acid into ethanol. Some of y'all love you some ethanol. I myself am not an ethanol consumer and that is not because ethanol is basically yeast pee, although that is a very interesting aspect of ethanol. Eventually the ethanol will kill the yeast. It's a poison and we can talk about, oh my gosh, ethanol is super interesting, but that's drinking alcohol and it is produced by the yeast. That's why when you make beer or you make wine, you produce an anaerobic environment. You don't let oxygen in so that you don't let the yeast get lots of energy. You force the production of ethanol in their process. They don't need as much energy as we do, so they don't die from that. The thing they die from is poisoning from the ethanol. Okay, this whole thing is awesome. Let's look at this next piece. We'll be really quick. We're just going to look at some other ways that other foods provide us energy through cellular respiration even if they're not carbohydrates.