 So the cytoskeleton is basically a diverse network of protein filaments, and we have multiple sizes and we can actually break them down and label them and classify them and memorize all those names. And it's not so important to me that you know the differences between the types of cytoskeletal filaments, but that you understand a general concept of, like, how do they work? What do they do? They're made out of protein. They function in movement of the cell, cell movement. And toward that, there's a couple of ways that this happens. The cytoskeleton can help move a cell kind of in the way an amoeba moves. Like, can you imagine, like, how amoeba have these little feet-like structures that blob out and then the rest of the cell, like, blows the blobbing foot that's oozing out? So you can have amoeba-like movement, but you can also have, like, movement of the entire cell itself using structures like cilia, which are made of cytoskeleton, or flagella. And I just have to draw you a picture because any time I get the chance to draw a flagellum, I have to. What is a flagellum? It's like a tail. Flagella usually are singular, so you usually find one on a cell and that is, like, a sperm. Sperm have flagella. Think about that. That is a single-celled, like, half a person who can swim on its own sperm or phenomenal. But what's a cilia? What are cilia? Maybe I better draw a nucleus in here and a little nucleolus. Here's my nucleus. Here's my nucleolus in this cell. Cilia are, like, a million little tiny flagella. And cilia, there are cells that do move like individual cells that move with cilia. There's also cilia-lined cells in your, like, trachea. And you, when you smoke, you poison your cilia. And that's why you cough because your cilia are actually functioning to bring the mucus up out of your lungs. Thank you very much, cilia. And they are poisoned by the poison in cigarette smoke. And so if you smoke, you, like, paralyze your little cilia and they can't get the guck out of your lungs, so you have to go, huh, and you have the smoker's cough to get the guck out of your lungs because you just poisoned your cilia. Dogs, don't do that. Stop smoking. Stop smoking right now. Eat ice cream instead. I want to show you a picture. I want to show you a picture of the amoeba-like movement of cytoskeleton. So each one of these things, each one of these appendages sticking out, there's actually cytoskeleton inside that. And it oozes out and takes cell membrane with it and enables, you know, let's yumpsilize the bacteria or let's actually move the entire cell itself, kind of like an amoeba. The other one that I wanted to show you, this is an example of cilia. They're made out of little protein filaments, so they are considered cytoskeleton. They look like little hairs embedded in the cell membrane itself. And again, they can, if it's a coal critter like this, a protist, then they can enable, like, let's just go, let's go for a swim, guys. And they all beat in sequence and you can go for a swim. Or they're lining your respiratory tract and praying that you do not poison them and praying that you stop smoking now. Okay, no, I have a video to show you. Okay, this is my all-time favorite video of ever and I'm going to show you just a part of it because we're going to look at it again and again and again and again because I love this video. Look, I threw that, whatever that is, right there, address of how you can get to this video and it makes you want to cry because it's so beautiful. All right, watch and be amazed. The music is fantastic, too. This is cytoskeleton. You're going to get to see, first of all, your cytoskeleton actually, like, forming kind of a skeletal structure of the cell. And let's take a look at that. This is your cell membrane up here and these are proteins. What there is, cytoskeleton. See how it's forming like a toughness of the cell wall. There it all is. That's awesome. Structure for the cell itself. I think we get to see it building and like, there it is. Oh my gosh, that's so cool. So don't, look at that. What? Okay, I have to pause. Seriously, this video just like blows my mind and I've, I don't want to tell you how many times I've watched it because I could sit and watch this video all day long. You tell. It's real. The, the science department at Harvard was like, dude, our biology majors can't get a visual of these molecular processes that happen inside a cell. Like, they can't visualize this, these processes that are happening. So they called up this company, X vivo, and said, will you guys do an animation that like rocks our world? And so X vivo was like, that's who keep up. And they made this and the best part about it is that it's basically an entire biology course in one process. Like you can see everything that we're going to talk about in here, which is mind blowing. But what you just saw were little proteins, little pieces of cytoskeleton that when chemically motivated will put themselves together to form cytoskeleton, which will, you know, reach out a pseudopodia or let's go, yum-scholize the bacteria, or break it apart. And you can imagine that it can build on one end and break apart on the other end and then you get this mass movement. Let's see if there's any more cytoskeleton stuff to look at. Oh my gosh, look at this thing. What? Okay, I have to stop. This is ridiculous. That, did you see that little blue thing there? That, or that's not blue. That's kind of a yellowish green. That matches my shirt. That thing is like a machine, an enzyme that went in and broke apart some cytoskeleton so that the cell could carry out some sort of fantastic function. It blows your mind into a million little pieces and this whole class, like, it will happen over and over and over again. Okay, go look up that video and watch the whole thing and be like, oh my gosh, I'm going to understand this at the end of the semester. I think that's it. And I'm going to come back and tell you about the cell membrane and its structure and some important functions. Okay, have fun. I'll see you later. Peace.