 Alright, so you're going to learn something about me today and this is the first time that we're going to see a couple of dead white guys. I refer to, first of all, I think it's interesting to know, like who figured this stuff out? I also think it's really interesting to know how did they figure it out. It reminds us that back in the day of whatever 1800, in the age of these two dead white guys, there wasn't like a textbook where we could go look up the different kinds of cells or what's inside a cell and there wasn't a Wikipedia where we could go and find out that, oh, here's a list, a comprehensive list of all the different types of cells. These guys literally had no idea that cells even existed and they're the ones who said, oh, it looks like they're, let's find out what are some basic truths about cells. And so they did this really important research, really important research that was groundbreaking at the time and still is relevant now. Like it still is informing what we do and how we study biology. Please understand that when I speak of the dead white guys, the fact is that most of our historical people that we're going to see in biology, most of them are white and most of them have penises. And that is not, it's the way it was. It's the reality of how science was run. Dude, Beatrix Potter, who wrote the Peter Rabbit book, she was actually a scientist. She loved studying lichens, which are fungi and algae symbiotic critters, which is awesome. And she did all this really amazing scientific research back in probably the 1800s and wasn't allowed to share her research with the rest of the scientific community because she didn't have a penis. That is unfortunate, but it's the reality. So for me, talking about the dead white guys is just that it's just an acknowledgement of the fact that, you know what, it's how it was. This is how things were. And I don't intend to diminish the value of their contributions. I just think it's interesting that they all are white with penises. Okay. So dead white guy number one and number two, Schleiden and Schwann, these fellows compiled a list of characteristics that together or a list of facts that together make up this idea of cell theory. And so let's take a look at the things that they came up with in 1839. So I won't ever ask you to remember names. Second of all, I probably won't ask you to remember specific dates. Probably it's good to know that it was in the 1800s that a couple of dead white guys came up with the cell theory. And it's probably important to know the main ideas carried within cell theory. So let's look at it. First of all, every single organism, living critter, consists of one or more cells. That we know, in fact, that's how we define whether or not something is alive. This is going to be relevant when we start looking at viruses at the end of the semester because viruses are not considered alive. And that's because they are not cellular. All cells, a single cell is the structural and functional unit of life. And we've already stated that as well. This one was not part of the original theory. And the reason it got added was because it was added to what disprove or provide evidence that the concept of spontaneous generation was totally bogus. So the third tenant is that all living cells come pre-existing cells. They don't just appear out of nowhere. Babies don't get delivered by a stork. They actually come from other cells. Fantastically, thank you very much. We actually get to spend a lot of time talking about where babies come from. Won't that be fun? All cells have the same basic chemical composition. They're all made of our biomolecules. And when we start looking at the cell itself, we're going to start looking at our biomolecules in more detail. All cells use energy. They have tools and equipment in their bodies so that they can, in their bodies, in their cell membranes so that they can use energy. And we're going to spend a good solid three lectures. Oh, I can't wait. I love talking about energy. We're going to blow up some gummy bears. It's going to be really exciting. So the energy is an important part of this whole process. And I don't have any at all. And all cells contain DNA. And this is interesting, too. We're going to spend, I bet we spend a total of six lectures talking about DNA, structure, function, and heredity, meiosis and mitosis, and we pass on this DNA, how we copy it, and then pass it on equally to all the daughter cells because remember, all cells come from existing, previously existing cells. It's really cool. It's really interesting. This giant list of a whopping six things, hopefully at this stage you're like, okay, sure, I can memorize that list. But by the end of the semester, you'll be able to look back at this list and be like, oh, well, of course. Uh-huh, yep, I know that already. And yes, I learned that as well. So this is just giving you kind of an overview of the situation. Now, there's two main types of cells. And that's what we're going to look at next. What are the two main types of cells?