 This cell is a eukaryote because it does have a nucleus. I'm going to trace my nucleus. Excuse me, I'm going to trace this cell's nucleus. Look at this thing. That's the nucleus of the cell. Now, the nucleus, why? Who cares? Why is there a dot in the middle of our cell? Why is there a ball in the middle of our cell and another ball inside it? It's because the nucleus is the structure, the organelle that holds the DNA. And DNA is a nucleic acid. We're going to spend, oh, three lectures, I think, talking about DNA, structure, and function. Not all, there are different kinds of nucleic acids. The nucleic acids were one of our four main categories of biomolecule, and DNA contains the information necessary to build proteins and make you. So the information in your DNA builds proteins to make you be the person that you are. So everybody pat your DNA. You patted some, there's some DNA in there somewhere. Only is there DNA inside of your nucleus. For us, our DNA is packaged into, you know, we actually have 46 molecules of DNA or 46 chromosomes inside our nucleus. We also have this little, to me, this thing looks like a rubber band ball, doesn't it? But it's inside the nucleus. Notice my nucleus is surrounded in black and I made this little blue circle around this structure which is called the nucleolus. Ole-us. The nucleolus has an important job. It builds ribosomes, ribosomes. And this matters because we're going to spend a day talking about ribosome function. Like, what does a ribosome do? And why do we, like, you've got a whole structure inside every single cell just to build ribosomes. It's actually kind of an important thing. The nucleolus is an important structure. The nucleus in a eukaryote is separated from the rest of the cell, just like the cell is separated from the extracellular fluid, the nucleus is separated from the rest of the cytoplasm by a nuclear envelope. And that is how, what makes you happy. I'm coloring my nuclear envelope. I circled the whole nucleus and so if I circled the whole nucleus, I'm going to be touching the nuclear envelope. The nuclear envelope is essentially like a cell membrane around the nucleus. It's like the Ziploc baggie inside the bag of soup that we had. It's actually made out of the exact same stuff that a cell membrane is made out of. And again, we're going to talk about cell membranes in the next entire lecture. The nuclear envelope, notice, if you will, notice the holes. Those are pores, I mean, they're literally holes. They're like those little grommet things in a hoodie, the little metal things that hold two pieces of fabric together, but make like a tunnel in between. That's what those things are like. They're holes that allow some stuff in and out of the nucleus, the plot thickens. Don't you kind of want to know what those are and why they're there? They're like secret passageways. Don't you want to go inside the nucleus and have a tea party with the nucleolus? I do. And I could go through one of those nuclear pores to get there. Shall we talk about other organelles that are defined in the eukaryotic cell, organelles that are in the cytoplasm, not in the nucleus itself. Let's do that.