 Hi everybody, Dr. O'Hare. This video I'm going to walk through some of the key cell organelles in our human cells, especially the ones that are involved in the production of new proteins and also new plasma membranes. So I'm kind of talking about what's known as the endomembrane system, but I really won't belabor that point too much. But it is, it is the nucleus and as you're going to see the nucleus is directly connected to the endoplasmic reticulum which is then connected through transport vesicles to the Golgi apparatus or Golgi body which is then connected to the plasma membrane. So it really is one big system and that's why it's called the endomembrane system. It's a system within, a membrane system within the cell. So but I'm primarily going to focus on the nucleus and the rough and smooth endoplasmic reticulum and the Golgi apparatus. You see here it's called the Golgi complex, so different terms sometimes. Let's go ahead and jump in. So here's just a close up look at the nucleus, but I also want you to note that it is directly connected to the endoplasmic reticulum. So inside the nucleus we do see the nucleolus here. The nucleolus is the site of the production of rRNA or ribosomal RNA. Like when we're generally, we're talking about transcription and translation, these types of terms. When we talk about RNA, like if I just say RNA, what I mean is mRNA or messenger RNA, that's the actual message that's being converted from DNA and RNA into protein. But the nucleolus makes the ribosomal RNA, the small and large subunits that make the ribosomes, which of course we can't, we can't translate proteins without those. So nucleolus is important. Then you see the chromatin. So chromatin is your DNA with the proteins that it's coiled around. So chromatin is what actually coiled itself into chromosomes. So you don't have chromosomes all the time. Chromatin forms chromosomes prior to cell division. So during, during mitosis, so that's the chromatin there. The nuclear envelope just double, you know, think, I think about like a vault, right? This is what houses and protects your DNA. See bacteria don't have the advantage of having this, this double membrane that protects their DNA. And then they have the nuclear pores, which is how the messenger RNA and other structures leave the nucleus to go to the cytoplasm, the guts of the cell. So that's the nucleus. And then we see how it's connected to the ER. So let's go ahead to this next picture. Here we see the rough and smooth ER. So they both, they both are this, this network of chambers. The difference is the rough ER is rough and the smooth ER is smooth. So what, what is that has to do with the ribosomes. So these little, these little circular spherical structures you see on the rough ER are ribosomes. They're actually called fixed ribosomes because they're attached right there. So, but both, but notice that the rough and the smooth ER are both connected. So this is all big, one big network here. So, so you think about like DNA is actually converted into RNA in the nucleus, then the messenger RNA is going to, once it's processed, we'll cover that separately when we talk about transcription and translation. But once the RNA is processed and cleaned up, it's going to snake out of the nucleus. And if it finds a, if it goes to a free ribosome, that's going to be a ribosome living on its own. If you want to call it that, it's going to be turned, it translated into a protein that's used by that cell. If it finds itself at a fixed ribosome, it'll be producing a protein that's actually going to travel through this endoplasmic reticulum and, and it's going to work its way out of the cell. So DNA becomes RNA in the nucleus. That messenger RNA goes and finds a ribosome. So here, the rough ER is the ribosomes on the surface. I like to use the term bedazzled, but if you're not as old as me, might not know what that means. But the, the rough ER is studded with these ribosomes. And when they make a protein, it's going to be in its primary structure, which means it's just a sequence of amino acids. When it enters the rough ER, it's going to be modified and packaged. So it's going to reach that stage where it reaches its secondary or tertiary structure. So important basic biochemistry terms there. So the rough ER is going to be modifying and packaging these proteins. Now the smooth ER, as you can see, doesn't have any ribosomes. So don't think proteins, but it makes lipids and carbohydrates, but still like wildly important. This is where the cholesterol and the phospholipids for your, for your cell membranes comes from. This would be where steroid hormones are produced. Your ER, especially the smooth ER, inactivates and neutralizes toxins. This would be the structure where glucose is turned into glycogen, like in your liver cells and your muscle cells. So very, very important. So these two are working together. The rough ER is modifying and packaging the proteins. The smooth ER is going to be adding cholesterol and phospholipids and hormones. But then the materials that are produced in this endoplasmic reticulum is then going to move into the Golgi. So here you see at the top, the nucleus, then you see the rough ER. Now the smooth ER has been inserting stuff too. But the rough ER is going to take these modified and packaged proteins and transport them through transport vesicles to the Golgi apparatus or Golgi complex. Now I don't care about the term cis face or trans face, but the cis face is where this stuff is incoming. And then as it travels through the Golgi, it's going to be, it's going to be tagged and prepared for transport out of the cell or, or at least to its final destination. Then when it reaches the trans face, then we're going to have all these products, right? So there's, you'll see that there's secretory vesicles. Those are going to go to the plasm membrane and then dump their secretions out into the environment. They're actually going to be vesicles that will just join the plasm membrane and actually help fix and repair and maintain the plasm membrane. And then also you can't see it in this picture, but there are vesicles produced here that become the lysosomes. So lysosomes are these bags of acid and digestive enzymes. So they're considered the kind of the digestive system of the cell. And their job is to engulf debris, maybe microbes, also old damaged organelles and break them down. So, so hopefully you can see how all of these organelles work together. Well, we'll get into more of the details of protein synthesis when we talk about transcription and translation. But I wanted to give you a background at least of the locations and the basic functions of these organelles. So that should be everything you need to know about the nucleus rough and smooth ER or endoplasmic reticulum and this Golgi complex Golgi apparatus Golgi body. I'm sorry. There's so many different ways to say it. That's, you know, I didn't make up the word. So I truly hope this helps. Have a wonderful day. Be blessed.