 Hey everybody Dr. O here. In this video I'm going to give you a quick overview of all the organelles of a typical eukaryotic cell like our human cells. So some of these will need some more detail and I'll do several videos but this will be like a just a high level overview. I'm just going to go right around the cell here like I did with the bacterial cell if you watch that video but let's go ahead and start kind of right near the top there with the cytoplasm. So the cytoplasm is everything inside the cell, inside the plasma membrane except for what's in the nucleus and some would argue about a few other details but really it's just the guts of the cell. So the cytoplasm is the cytosol, the fluid portion of the cell plus whatever organelles are swimming inside of it. Alright that's the cytoplasm, the guts of the cell. Then you have the plasma membrane. So the plasma membrane is a selectively permeable membrane and it's very important because it plays a role in keeping what we need in our cells in, keeping what we need, what we need out of our cells out and then moving things back and forth. So the plasma membrane, I'll do a separate video on it, it's a phospholipid bilayer but it's a very very important. Now what makes this unique versus the plasma membrane in a bacterial cell is our plasma membranes have cholesterol in them. Cholesterol is a dirty word in our culture but all of our cells have and need cholesterol because cholesterol is what keeps our cells from tearing open. It's what makes our plasma membranes strong and they are so strong that we don't need a cell wall. So plant cells don't have cholesterol so they need cell walls. Bacterial plasma membranes don't have cholesterol, they need cell walls. So we don't because of cholesterol. So it's actually a really good thing in this context. Next, this purple structure here, we have the nucleus. Inside the nucleus is the nucleus. So the nucleus is where our RNA or ribosomal RNA is made and then the ribosomal subunits are put together. So it's a factory making the ribosomes that we'll need all over the place. Next is just the nuclear envelope. So it's actually really similar to the plasma membrane so it's a membrane that houses and protects what's inside the nucleus which includes the nucleus but also obviously your DNA, your 23 chromosomes. So that's the nucleus. People call the nucleus the control center of the cell. What I would say about the nucleus is this. It controls protein synthesis or people call it the brain of the cell, right? If you were to ask me what's the brain of the cell, I would say the plasma membrane, the cell membrane is the brain of the cell. It's what senses the environment and responds to what it's sensing in the environment. So as far as like receiving information and making changes based on it, I actually consider the cell membrane or plasma membrane to be the quote unquote brain of the cell. The nucleus though does control protein synthesis. So the conversion of DNA to RNA and RNA into protein. Then lastly in this area, we have the nuclear pore. Those are just the openings so that your RNA can leave the nucleus and go find the ribosomes here in our eukaryotic cells. The next two are related. We have the rough and smooth endoplasmic reticulum. So they're both these, they're both your kind of flatten chambers where materials kind of move through them. But the key difference is the rough ER as it's called is studded with ribosomes. So the reason it's rough is because it's covered in ribosomes and the smooth ER is not. That's why it looks smooth here. So the rough ER think about ribosome with ribosomes do as we'll get to in a moment. They're responsible for the production of proteins or protein synthesis, the site of protein synthesis. So the rough ER think modification and packaging of proteins. Those proteins are being produced by ribosomes. They're being modified and packaged there in the rough ER. Smooth ER doesn't have ribosomes. So think nothing to do with proteins. They make lipids like like part of your cell membranes. They make lipids and they make carbohydrates. The other key thing that the smooth ER does is that it activates toxins. So you'll see like the liver cells are going to have way more smooth ER than a lot of cells. So that's your rough versus smooth ER. I'll come back to ribosomes again in just a moment because there are two different types of ribosomes. I want to make that clear. So that's rough endoplasmic reticulum and smooth endoplasmic reticulum. Next we have the cilia. So cilia are going to be on the surface of some cells. Just a note here. Bacteria don't have cilia. So if you see a microorganism that has cilia on it, it must be a eukaryote. But so cilia are used for movement. They can actually if you're a single celled organism, they can propel you and move you through the environment. But most human cells are going to be connected to other cells in tissues and they're also going to be connected to connective tissue often called the basement membrane. So if there are ciliated cells on our human cells, they're going to be moving material across the surface of the cell rather than moving the cell. But the cilia think movement, either the movement of a single celled organism or the movement of material across the surface of a cell. So very important examples we'll get to. One organ that's not on here that this makes me think of would be the microvilli. So if the cell has there, they're not as long as cilia and there'd be more of them. But if a cell has shorter structures called microvilli, villi means finger. So imagine microscopic fingers. Microvilli, their function is to increase surface area. So if the cell is going to be absorbing or secreting a whole lot of material, it'll often have microvilli on its surface. We'll cover that when we get to histology. So that's the cilia. Next here on this image, we have the Golgi complex. I call it the Golgi apparatus, but another section of flattened sacs. I think of it like as the shipping and receiving center of a cell. So it takes materials and it modifies them, alters them, packages them and then puts them in secretory vesicles so they can be sent out of the cell. So that's why I think of it kind of like a Amazon warehouse or something like that where it's taking material, it's putting tags on it so this material knows where it should go and then it's sending it out into the world. So that's that's the Golgi complex or Golgi apparatus. Paroxysomes. So they're going to they're going to help break down fats or other organic compounds. But the key thing here is not only can they do that, but they neutralize the toxic byproducts that happen during that. When fat, you know, think about fat like going rancid, right? When fat breaks down, it does produce toxic products. So the paroxysome can break down these materials but also neutralize any toxic products. Probably the reason that our cells don't don't wither and die in age way too quickly. So that's the paroxysome. Next, you have the lysosome. I personally think this one's more important. I always call this the digestive system of the cell. Think of it like a stomach. It's a bag basically with dozens of digestive enzymes in it and acid. So just like your stomach has acid and enzymes, the lysosome has the same thing. So this bag of acid with digestive enzymes, I think there's 40 to 50 of them, there's argument there, but lots and lots of different enzymes. So it can break down a whole host of things. It can break down like like food stuff, but it can it can break down bacteria that get in the cell. But one of its major functions is it breaks down damaged organelles. So one of the reasons that our cells can stay alive so long is when organelles have been damaged, they're broken down and replaced and the lysosome plays a major role there. So lysosome think digestive system of the cell. Next here we have microtubules. So just real quickly, microtubules and then a few over their microfilaments. Those both make up your cytoskeleton, the skeleton of the cell. The difference is a microfilament is a solid structure and microtubule would be hollow, but I think they help they help give the cell shape, but they also help with the movement of materials. So things can actually be carried along their surface. So think cell shape, cell structure, but also helping move material through a cell. But they're relatively minor. All right, that's the microtubule, the mitochondrion or mitochondria. This would be the power house of the cell. So think about like a coal burning power plant or something like that. This is where 95% of your cell's ATP, which stands for adenosine triphosphate, is going to be produced. So the reason it's 95% is as we'll cover in the sections on metabolism. Glycolysis doesn't happen inside the mitochondria. So those first couple ATP are produced outside of the mitochondria and the rest are produced inside of it. So mitochondria, I think power house of the cell, 95% of ATP is produced here. Give or take. All right, that's the mitochondria. Next we have the ribosome. So the ribosome, site of protein synthesis or the site of translation if you want to use the more technical term. Key thing here. So as I covered in the bacterial cell structure video, our ribosomes, most of them have a different shape than bacterial ribosomes. This is why so many of our antibiotics attack the 70s ribosomes of bacteria because our ribosomes are called 80s ribosomes or 80 Svedberg units. I don't care about that term. That's not 100% true though because our mitochondria, which you just talked about, they do have their own ribosomes and they are 70s ribosomes. So this is kind of an interesting fact. So ribosomes think protein synthesis or translation, but very important here. I want you to know that there are two types of ribosomes, free ribosomes and fixed ribosomes. So the little dots that are off on their own are called free ribosomes. The ribosomes that are on the surface of the rough endoplasmic reticulum, those would be fixed. So they're attached to something else. Here's the key difference. Free ribosomes think proteins are being produced that are going to be used in this cell by this cell. Fixed ribosomes are going to be proteins that are going to be sent out of the cell. So if the cell is making a protein that it needs, it would be using a free ribosome. If it's making, let's say this is a pancreas cell and it's making insulin, insulin, the protein will be made by a fixed ribosome and then modified and packaged by the rough ER and sent to the Golgi and then secrete it out into the body. So that's the two types of ribosomes, free versus fixed. I already mentioned microfilaments, just a couple more here. The centrosome is where your two centrioles are. So every centrosome has two centrioles sitting at a right angle to each other and these are necessary for cell division. They actually, they align and pull your chromosomes apart during mitosis. So if a cell doesn't have a centrosome or doesn't have centrioles, which is the term I use more often, the cell can't divide. Think about like most of your neurons, for example. So that's the centrosome and the two centrioles that are in it. Then we have the flagella. So our flagella is really just a contractile whip-like flagella versus the rotary motor system of a bacterial cell. So it's actually an area where their cells are more complex than ours. But flagella, think movement, and that's all of them. I know that's a lot. So I'd go through this video a couple times and like I mentioned, I will make more detailed videos on the on the organelles that need it. Okay, but that's a nice walk through of the parts of a eukaryotic cell like our human cells. Have a wonderful day. Be blessed.