Ep 10 - Inside the cell city

Episode 10: Inside the Cell City 🧬

What if your cells weren’t just blobs… but fully functioning cities?

In this episode, we take a tour inside the eukaryotic cell — where proteins are built, packaged, shipped, and even recycled. From the rough ER and Golgi apparatus to lysosomes and motor proteins, every part of the cell has a job.

And none of it was planned.

Every organelle exists because it solved a problem — one solution leading to the next, turning simple cells into something incredibly complex.

🎧 Next: Sexual reproduction — one of the strangest innovations in the history of life.

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Transcript

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Jackie 0:01

Hello, I'm your host Jackie Mullins and welcome to From Cells To Us, how the podcast where we figure out how life went from a single cell to complex creatures like us. So where are we? Well, a cell figured out how to use oxygen for energy. It grew bigger. It grew blebs. It accidentally enclosed its own DNA and invented the nucleus. We have a eukaryotic cell nucleus mitochondria, flexible membrane. The basic house is built. But here's the thing about a house. Having four walls in a roof doesn't mean it's livable. For any of you who ever tried to run away to a tree house, I'm sure this became apparent as soon as you wanted a cup of water, had to go to the bathroom. Or on a more adult note, I suppose if you ever built a house or done a major renovation, red Walden, you know, same thing. Four walls and a roof is just the beginning. You need plumbing, electrical furniture, a system for getting things from room to room away to take out the trash. Today we're doing the full tour, but before we start that tour, let's take stock of where we are. It's roughly 1 billion years ago. We're in the Mesozoic era, and now this could really be called episode 8.5 because what we are covering is what happened after the mitochondria integration, but before the chloroplast integration. So why did I go out of order? Well, the mitochondria and chloroplast story was so similar. I wanted them to be back to back so everything was fresh. Am I second guessing that decision? Uh, yes. Honestly, a little bit. I probably should have just kept them in order. However, what's done is done, live, learn, and then get loves. And, uh, maybe you're like, well, how do we know? That's the actual timeline. Like why couldn't chloroplast have come before the infrastructure of the cell? And that's actually a great question because the answer is what scientists use a lot to help decide timeline. It's called principle of common descent. Plant and animal cells both have the same or very similar organelles. And as a rule, if that happens, it's likely because it evolved once. From a common ancestor and then they split, which makes sense, right? Because a complex organelle would likely only evolve once, not twice. They'd be like giving two people a box of random Legos and coming back and seeing that they built the same exact thing. That's not very likely. What actually happened is they worked together on the first part and made the same base. Then they take their identical bases and wander off in different directions. No drama, no falling out, you know, they just drift. But now they start building separately and slowly their structures start looking different. But that base always the same. Always carrying the memory of what they built together. And it was kind of sweet. And that's the case with animal and plant cells. As soon as a chloroplast came in the picture, they started building with different materials, sunlight. And remember in the first few episodes, I'd be like, cells that figured out how to be with DNA instead of just RNA thrived, and all others died. Well, we've hit a cool part in the timeline Where there isn't just one path forward, evolution has figured out a few ways that work. So even though some eukaryotic cells didn't swallow a chloroplast, you can raise your hand, that's you. Their mitochondria was enough to still keep them thriving just differently. So to clarify, the cell right now has just swallowed a mitochondria and the nucleus has been formed. But eukaryotic cells are mansions, right? That's what I said. Well, today we're talking about all those rooms, all those organelles we're talking about what those rooms do and why each was essential. And this happened like everything else has happened in this podcast, right? Accident selection, accident selection, every organelle. Earned its place by being useful enough to be kept around. You know, there were no Nepo babies here. You know? Oh, you know who? Well, let's get Bobby. Set right up next to the nucleus. No, each organelle started up and did a task better than anything else did before and after. Because there is no second place in evolution. There are only winners. If you're not first, you're last. Every organelle is a solution to a problem. Let's find out what problems they were solving. All right, look at your hand for me. Closer. Closer. Yep. Even closer. We're going to use our magic microscopic vision here. Or you know what, if we're making things up, let's, let's just shrink. Ray it up, honey. I shrunk my audience or, or more accurately that 1966 fantastic voyage movie, right? Where they take a submarine into someone's body, but we are going even smaller because we're going somewhere even more microscopic. Yes, my friends, we are going on a journey. Through your cell. So if everyone will please watch your step, mind the gap. Just don't fall as we load our shrunken submarine to take the tour. First stop is the stuff all around. It's what everything is moving through and just kind of sitting in. Yes, welcome to the cytoplasm. This is the stuff that fills the cell. The cytoplasm is a gel-like fluid called cytosol, a watery solution packed with protein, salt, sugars, and all the raw materials the cell needs to do its job. You know, it's just like that slop you had to eat when they. Unplugged you from the matrix. There is amino acids waiting to be grabbed by ribosomes. There's glucose waiting to be grabbed by mitochondria so it can make precious a TP. Our cells quarters, there's fatty acids waiting to be used for new membrane. Think of the cytoplasm, like the city itself, the air, the ground, the space in between the buildings. Everything exists within it. Everything moves through it. It's not glamorous. Nobody's making a documentary about cytoplasm, but without it, nothing works. And here's the thing about moving through a gel. It's not like moving through air. Things don't just float freely from one place to another. Distances that seem tiny to us are enormous at the cellular scale. A protein that is made maybe to go all the way over to the other side of the cell, and it can't just drift there in this jello like substance. Have you ever tried to move in jello? Well, me neither, but I can't imagine it would be easy, So remember that problem as we move through our tour, but we are not hitting the solution to that problem right now. If you will look to your left or whichever way you picture it, we have arrived at our next destination. The endoplasmic reticulum, usually just called the er. Because, well, I'm sure you can figure that out. You're all on episode 10 now, brainiacs a lot of you now, as you can see, the ER is placed right next to the nucleus. It is an enormous folded membrane system that winds through the cell like a maze. If you unfolded the er, it would cover an area many times larger then the cell itself, it's like one of those magician scarves, right? That just keeps coming out of the pocket. Like how much is in there? How do you not have puffy sleeves like Anne of Green Gables as she's about to go to the big social, you know, the world may never know, but what we do know is that ER comes into flavors. Shall we say there is the rough er and that is covered with ribosomes. Remember Rick, this is where some Ricks reside. A bunch of Ricks saw the rough er. It had good schools parks close by, so they decided to make it their own personal subdivision setting up house, ser house in this maze of the membrane, just waiting to host their parties. So naturally, Mary and Tina come and visit anytime they can. By which I mean anytime daddy DNA starts up the central dogma, so the rough ER is studded with ribosomes all along its surface, which is why it looks rough under a microscope like sandpaper. If you see rough ER in a drawn picture of the cell, they usually just put dots on there representing ribosomes, and those ribosomes are churning out proteins constantly. The er Ricks make proteins to take out of the cell for the cell membrane or for other organelles. You know, these poor Ricks don't get a break here. The suburban life was harder than they thought. However, all Ricks do not live here. Some are free floating hippie ricks, shall we say. And they're living in the cytoplasm, man. They're taking care of their own mother cell 'cause we're all connected. AKA, these hippie Ricks floating in the cytoplasm, not on the er. Make proteins that stay inside the cell and do their job in the cytoplasm. Mostly proteins for cell structure and transport. So the distinction is really destination. If the protein needs to be packaged and sent somewhere specific, it gets made in the rough er. If it's going to hang around in the cytoplasm doing its job, it gets made by a free floating hippie Rick. Also, something fun to know, the ratio of er Ricks to hippie Ricks is basically a job description for the cell. For example, take pancreatic cells, the ones that make your digestive enzymes. Their whole job is manufacturing and shipping proteins out of the cell constantly. So their rough ER is enormous. It takes up most of the cell wall to wall, er, suburban Ricks with briefcases and neck ties. It's basically an Amazon fulfillment center in there. Every Rick on shift, this is full consumerism. Lots of things being made, lots of things getting sent out. But muscle cells, different story entirely. Muscle cells are mostly doing internal work, right? Building structural proteins, maintaining the machinery that makes them contract. Most of their Ricks are hippie Ricks, floating free in the cytoplasm. Local production for local use. Things made for that specific cell. No shipping department needed. Same rick, completely different ratio. Depending on what the cell does for a living. The hippie Ricks and the corporate Ricks, same training, different calling. Now if you turn your head the other way and look out the window to see the other flavor of er. This is the smooth er. This ER has no ribosomes smooth surface, different job entirely. The smooth ER makes lipids, fats, which are essential for building new membrane. Every time the cell needs to grow its membrane, extend a bleb, build a new organelle. The raw materials come from the smooth er. It's like the cell's home depot. Anytime something needs to be built or expanded, a new organelle, a growing membrane, a bleb reaching out to grab something, the smooth er is where you go for the materials. But wait, the smooth ER also detoxifies things. Yes. You heard that right? The smooth ER is both Home Depot and Poison Control. Sounds odd, right? Like why would they be in the same place? Well, they both needed a work space, a desk. And that's the ER membrane. So they basically work on the same desk but just with completely different tools. And the detoxification is obviously just as important. And while it does this in several cell types, your liver cells are where this really becomes a full-time job. The smooth ER is working overtime here. It's the best departed accent I could do. So when you have a night out drinking. And you know, thank your liver for taking one for the team. Get a little more specific. Thank your smooth ER for getting those toxins out, or perhaps curse them the next morning for not doing a better job. So to end our ER tour in the cell city, the rough ER is the city's factory district. If you were playing sim. This is what you would've highlighted as Blue. The suburban Ricks constantly manufacturing products for export. The height of consumerism, the smooth ER is Home Depot and Poison Control your one stop shop for lumber and hangover meds. Okay, we'll continue our tour, but we won't have to go far because the ER needs this to be right next to it. Welcome to the GOGI apparatus. GOGI named after Camilo GOGI and discovered in 1897 and probably had no idea how important it would turn out to be. The GOGI is a stack of flattened membrane sacks. The ER and the GOGI are always drawn pretty similarly, except the ER is like the messy one, and the GOGI is the neat one. Which kind of tracks, because here the ER is just like churning out materials and proteins and then they just release them. But how do they know they're going to get where they need to go? Well, that's where the NEAT and responsible GOGI comes in. The GOGI is the processing and shipping center. So the chaotic rough ER has suburban Ricks churning out proteins. Right after they're made, they get put in little bubbles called vesicles. I kind of picture it like meet the Robinsons when the people are using bubbles to travel and I also can't help but imagine rough ER training their new employees like Mrs. Doubtfire, well, you take these proteins, you box them, you ship them. Then you take these proteins over there. You box those, you ship those. Then the one rick is like, after you box 'em, what do you do? You ship 'em. All right, so this bubble travels to the GOGI and fuses with it. The protein is now free and inside the gogi. Now the protein moves through the GOGI in stages. Remember, the GOGI is a stack of flattened membrane sacks, and the protein gets passed through them one by one getting modified and tagged at each stage, like going through custom checkpoints. Once the protein is processed, the GOGI packages it into a new vesicle, a different box, which is addressed to its final destination. The vesicle travels to where it needs to go, fuses with the membrane there and delivers its contents. Without the GOGI proteins would just be floating around with no address, no destination The cell would be manufacturing things with nowhere to send them. So the rough ER is the factory district, right? The Amazon warehouse, making things constantly. And the GOGI is the distribution center, sorting, labeling, and routing, everything to the right address. And as we make our way out of the Golgi, we will remember its neat stacks and the ER's winding paths, each cell having only one of each. However, as we head to our new destination, we have plenty of opportunities to catch one as there are multiple in each cell. Ah, what luck. Here's one. Now, what you are looking at folks is called a lysosome. Lysosomes are small membrane bound, sacks filled with digestive enzymes. I kind of think of them like the sarlacc. You know that weird sandpit monster with teeth and Star Wars, return of the Jedi, or they almost throw Han solo into it, but get this one that could move. And their job is to break things down, anything the cell needs to get rid of. Old damaged organelles, invading bacteria, worn out proteins, cellular debris. The lysosomes come by with their digestive enzymes and break it apart. And remember, enzymes are like those green ghost warriors from Lord of the Rings. They speed up chemical reactions and they are never used up. That's a big episode two callback. So picture these membrane sacks filled with these Green Ghost warriors ready to fight when called upon. Oh, and I can't believe our luck a bacterium has just been engulfed into our cell. See how the cell membrane wraps around the bacterium and pinches off creating a bubble. The target is now sealed inside its own membrane bubble inside the cell. This bubble now sends out chemical signals essentially saying, I have something that needs digesting. Look how the lysosomes receive the signal and start moving along toward the membrane intruder. Now see how the lysosome fuses with it, like hoses, refueling a spaceship. And thankfully, because we don't want any of those digestive enzymes to get outside their membranes, if they do, they can digest its own cell. Now the two membrane bubbles merge into one big bubble. The digestive enzymes or green ghosts from the lysosomes are now locked in a cage match with the target. Fight The enzymes get to work, breaking everything down. Proteins get chopped into amino acids. Fats get broken into fatty acids. DNA gets smashed into nucleotides. Everything gets reduced into basic building blocks. And those basic building blocks, they don't get wasted. They get transported back out into the cytoplasm and reused the cell. Reuses almost everything. Very environmentally conscious. And the really cool part if you think about it, is that those nucleotides that just got broken down from a bacterium might become part of your cell's new instructions. Your next Mary could be made from parts of an invading bacterium that your lysosome just ate. And so we are all connected in the great circle of life. Mufasa strikes again. Now. I mentioned that the digestive enzymes, the ghost warriors needed to be contained, and that's true if the lysosome pops open. The ghost will wreak havoc and digest things they're not supposed to. But what about small leaks? Occasionally a single cell or a couple ghosts may slip through. You know what happens then? Well, inside the lysosome it's kept acidic, but why? It takes energy and specialized pumps to maintain this, but the cell does it deliberately, and here's why. Think of it like a fish that needs a very specific water temperature to survive. Maybe you try to clean the tank and accidentally put the fish in a different temperature and, well, I'll let you write the ending to that one. That's the same with the few escaped ghosts They get outside the lysosome, their acidic home, and into the neutral cytoplasm. And they don't work anymore. They're useless. That's the fail safe of the cell. However, if there's a full rupture of a lysosome, the dam breaks. If the leak is big enough, the cell might not even survive it. But if it's a small leak, if a few ghost warriors slipping out into the neutral cytoplasm, they stop working and float away harmlessly the fail safe holds. Okay. Now, what about mitochondria? And maybe you're like, what the heck do they have to do with any of this? Well, a lot actually. Because something special happens with them when they get old. When they get damaged, when they stop functioning properly, the lysosomes come for them. Okay, well that's actually no big deal because they do that for any damaged organelle. That's autophagy. But mitochondria gets special treatment. Why? Well, because they have their own DNA and you can't just randomly degrade something with different DNA than your cells. Why? Because if mitochondrial DNA escapes into the cell, it can trigger inflammation. Your immune system treating your own mitochondria like bacteria, which to be fair, to be fair, they basically are, old habits die hard even after 1.5 billion years. So the cell developed a very careful system for dealing with them. Specifically. They can't have any. Tom Dick or Harry Lysosome, come and get them. They got labeled as biohazard. They need the special ops, the lysosomes with the hazmat suits. The guys that handled et, you know, the ones with the white suits that showed up at Elliot's house, completely sealed it off, not taken any chances. So when mitochondria are damaged, they essentially wave a flag that says, I'm done. Come and get me specific proteins. Mark them for pickup. The lysosomes come, the mitochondria gets recycled. They call this process mitia, specifically the recycling of mitochondria. It's part of the same autophagy process that we talked about in episode nine on what happens during fasting. Also something worth noting, lysosomes probably weren't there for the very first acts of phagocytosis. The digesting of cells early phagocytosis was like eating with your hands. It worked. Things got consumed, but it was messy and inefficient. Lysosomes are like eating with proper utensils at a set. Table more organized, more controlled, more efficient. The eating came first. The table manners came later. I think of this kind of like the show Vikings, when King Eckert invited Ragnar and his Vikings friends to eat with him, and they just dug right in without. Saying Grace or using the forks and all the fine folk were like, my word, it didn't look pretty, but they got fed. So in our cell city, the lysosomes are the cell's, garbage disposal, stomach and recycling center, all in one. Okay, well I don't know about you, but the lysosomes were a bit much, let's find something a little less sinister. Ah, yes. Here we are. Welcome to the s. S are essentially storage compartments, membrane bound sacks that the cell uses to store things, water, nutrients, waste products waiting to be dealt with, pigments, whatever the cell needs to keep on hand. Now I know we're not there yet. Evolutionarily speaking, but it's worth knowing in present animal and plant cells that fas are quite different. In animal cells, s are are small and there's usually several of them in plant cells, there's typically one enormous central vacuole that can take up 90% of the cells volume. It's so big, it basically pushes everything else to the edges and it serves a structural function too. When it's full of water, it creates pressure that helps the plant cell maintain its shape. That pressure is called turor pressure, and it's why plants wilt when they're dehydrated, which I always kind of giggle at because Turor rhymes with Igor. And Igor has a hunch just like when plants wilt. So in our cell city. The VAs are the storage units, the water towers, and the structural support system all in one. Not the most glamorous organelle, but you know, you try running a city without storage. It'd be pandemonium. Dogs and cats living together, you know, it just wouldn't work. Now, as I'm sure you're aware by now, these proteins and things are not in a sweet, miniaturized submarine like us. They can't just turn on the engine and make their way through the cytoplasm. Our next stop, or should I say, our next ride, is the cytoskeleton We've talked about the nucleus, the mitochondria, the er, the gogi, the lysosomes. All of these are rooms in the cell city, distinct compartments with distinct jobs. But how does anything get from room to room? No submarines. You know, they're not like teleporting. It's not Star Trek up in here, nothing's beaming anywhere. They need a legitimate way to move around. In real cities, you have roads, highways, delivery trucks, a whole infrastructure that moves, things from where they're made to where they need to go. And the cell actually has that too here in the cytoskeleton. And there's something neat about it. It's not static. It's not like the skeleton in your body fixed and rigid. The cytoskeleton is dynamic. It builds and dismantles itself constantly in real time. You know, it's like the, the stairs from Harry Potter, the cell can reshape its entire infrastructure in minutes. Can you imagine if our bones could do that? Uh. Ew. Wait, I, I actually don't like that. That's way too creepy. But what about highways? Can you imagine if one highway went north and south one day and the next day, east and west, I would literally never be able to go anywhere again. Now the cytoskeleton is made of three main types of protein filaments. There's the micro filaments. These are the thin flexible cables that run throughout the cell. They're involved in cell movement, cell division, and changing the cell's shape. When your immune cells squeeze through the walls of a blood vessel to get to an infection site, that's micro filaments. Letting the cell reshape itself to fit through tiny gaps. You know, that's like Alex Mack turning into a puddle so she could slide under a door. They change their shape to fit where they need to go. Then there are microtubules. These are the highways, larger, more rigid tubes made of a protein called tubulin, which I always imagine proteins yelling. This is tubular as they make their way through them. So these guys kind of look like licorice, whips, thick outer shell and a hole all the way through. Last. There are the intermediate filaments, the structural cables. They are what keeps the cell from being torn apart. When it gets stretched and maybe you're like stretched, what do you mean? Well, think about your skin cells. Every time you bend a finger grip, a steering wheel bump into a doorframe. Like are you ever really thinking, oh geez, I hope my cell doesn't break. No. And that's because of these guys. So to map this into our cell city, the micro filaments would be the scaffolding that goes up when the building is being constructed or renovated. Temporary, flexible shape. Defining the microtubules are the highways, long, rigid directional tracks that things travel along. The intermediate filaments would be the steel framework of the building. The steel rebars inside concrete. They give structure and strength and resistance to being pulled apart. Now, it always makes me laugh when there's a eukaryotic cell diagram because there's always like these. Thin lines, almost like the pencil dropped and scuffed it on accident and they're like, oh, here's, here's the cytoskeleton. The picture really underwhelms you with the importance of the cytoskeleton and how it's actually laced throughout the cell. They are all very important, but the microtubules are the ones I really wanna talk about because of what travels along them. So as we make our way through the licorice whip, like micro tubule, you'll start seeing little helpers. And these helpers are motor proteins because a highway is. Great, but it means nothing if you don't have a vehicle to move things. These motor proteins are the trucks. They literally walk along micro tubule tracks carrying cargo. They have these little feet called domains that take alternating steps along the microtubules surface. One foot. Forward, another foot forward walking along this highway inside your cell. There has been this video going around showing this and it cracks me up. It's literally like this giant footed bozo character carrying something about 1000 times its size, and it's just like, do ddo, ddo, DDO just like humming to itself as it makes its way through the microtubule. And what are they carrying? Well everything. Remember when I was like the GOGI sends proteins places, but also said nothing travels through cytoplasm. I mean, at least not well. Well, this is the solution. Those vesicles are packaged up. Proteins coming from the gogi, mitochondria being repositioned to wear energy is needed. Most chromosomes being pulled apart during cell division. That is what they're carrying. Everything But these little workers aren't doing it for free. They wanna get paid money please. They want their A TP. Each step requires One A TP molecule. That's a lot of a TP, thank goodness. One of our ancestors was hungry for mitochondria one day, or I suppose alpha proteobacteria as it was not fully domesticated yet the whole city runs on a TP, the same currency. So in our cell city, the motor proteins are the delivery trucks. Okay folks. Our tour is winding down to the end, but we have one last trip to make the outer wall, the thing that's keeping everything in this cell safe and in one place, the thing that will prevent any white walker from invading the men of the night swatch, oh wait, my bad, wrong wall. But same basic idea. Keep the bad stuff out. Let the right people through. So let's zoom through a micro tubule and head there now. Now I've mentioned the cell membrane a few times, and I have been known to call it a bouncer. Bad at its job. Too flexible, too leaky. But that was then the membrane has leveled up considerably. And honestly, it had to because it was asked to do two completely opposite things at once. First it had to be as wall like as possible to make up for losing the rigid cell wall. But then the cell city started growing and suddenly it was all like, we need supplies and messages and nutrition. So it needed to keep everything out, but also let the right things through. That's genuinely a tricky combination. Here's how it did it. The foundation is still our spherical Oreo all the way back from episode one. The phospholipid bilayer, same cookie, but now it is studded with proteins doing very specific jobs. Same Oreo, much more sophisticated studs. Some are channels, highly selective gates that only let specific molecules through based on size, charge, identity. These are our new bouncers. You need to be on the list or you being bounced. Some are receptors. These are more like messengers. Hormones don't enter your cells. Isn't that wild? They actually just knock on the door, you know, bind to the receptor on the membrane, and the receptor passes the message inside like a sly handoff, and then the hormone just kind of stalks away. Some are identity markers, these are the proteins that stick out from the surface holding a flag that says, this cell belongs here. Friendly. Do not attack. Please think of them like the town lookout in the watchtower yelling. The moment they spot an invader, your immune system reads these to no self. From non-self, and this is why organ transplants are so complicated, the new organs identity markers don't match the new host and your immune system sees it as a foreign invader and tries to reject it. Your own body attacking something that's trying to save it. And there are adhesion proteins allowing cells to stick to each other in the right configuration. You can think of them like the city planner. Before you can expand the city, you need to know what materials are compatible with what's already there. Liver cells need to find other liver cells. Heart cells need to find other heart cells. The wrong connection and the whole structure falls apart. Four types of proteins, four completely different jobs, all embedded in the same Oreo. The cell membrane isn't a passive boundary anymore. It's one of the most. Sophisticated border control systems have evolved. Deciding constantly what comes in, what goes out, what signals get received, and who belongs in our cell city. The membrane is the border control customs, the watchtower and the city planner all in one. That's a lot. Now, maybe you're like OMG bacteria. If eukaryotes have evolved all this new stuff, what the heck are bacteria like Now, how. Evolved. Are they, what's their new gear? Well, that's kind of the funny part because if the name of this podcast was from Cells to Bacteria, we could cut it from about 50 episodes to 12 because bacteria and AA were doing the same thing as they've always done. No nucleus, no organelles, no elaborate infrastructure, just the same efficient, streamlined lifestyle. They perfected. 3 billion years ago, pro coyotes looked at eukaryotes getting complicated, and they were like, Ugh, geez, that's a lot of work. We're good. We're good. Right where we're at? And they were right. They still massively outnumber us today, but complicated. Unlocked something pro coyotes never managed. Working together, and that's where we're going next. But let's do a checkpoint here. The full city. Let's take stock of what we've built and what we've toured. The nucleus, that's the headquarters, DNA. Protected, controlled, built from episode eights inside out. Bleb model the mitochondria, power plants, former bacteria, episode eight, paying out the city's workers in a TP. The rough ER manufacturing district, ribosomes making proteins for export. Then the smooth ER lipid factory and detox center, home depot and poison control GOGI apparatus. That's the post office sorting and shipping proteins to the right address lysosomes, that's our garbage disposal. Digestive enzymes, breaking down cellular debris and recycling everything. VAs storage units and water towers, cytoskeleton, the roads and structural infrastructure dynamic, constantly rebuilding itself. Motor proteins, those are our delivery trucks. Going along the micro tubular highways carrying cargo, powered by a TP and then the cell membrane, not just a wall. An active border crossing with channels, receptors, identity markers, and adhesion proteins. Our bouncers, message runners and watchtower guy, this is the eukaryotic cell. Fully equipped, fully operational, ready to do something. No prokaryote ever could work with other cells. Alright, so here's the thing about everything we cover today. None of it was planned, right? None of it was designed. Each organelle solved a problem that arose from the cell getting bigger and more complex and more ambitious. The ER developed because proteins needed to be made and shipped. The GOGI developed because the ER needed a sorting system. The lysosomes developed because the cell needed to manage its waste. The cytoskeleton developed because a bigger cell needed an infrastructure to move things around. The motor protein developed because the cytoskeleton needed something to use it. One problem, one solution, which creates the next problem, which requires the next solution. That's how you build a city. That's how you build a cell. That's how you build complex life. Rome wasn't built in a day, right? Well, neither was your cell. And we are now, for the first time in this podcast, looking at a cell that is capable of doing something genuinely new. Not just surviving, not just eating, not just making energy, but potentially working with other cells, communicating, cooperating, specializing on a way we've. Never seen. Next episode, we're going to talk about one of the most significant and strangest innovations in the history of life. Sexual reproduction. Yes, it evolved this early. A very old and ancient custom. I do believe we're still practicing today. Why did sexual reproduction evolve? Why is it actually a wildly risky strategy compared to just cloning yourself? And why did it end up unleashing an explosion of diversity that changed everything? Well, that's a topic for episode 11 and three. Quick notes here before I sign off. One. If any of you are out there thinking, what the heck, I want to get to the real stuff. Screw you, stupid cells to you. I say, fair. I get it. I too was once young and wild. But to understand people, you know, you need to understand a person. To understand a forest, you need to understand a tree. To understand life on earth, you have to understand the cell. There's no escaping it I went to South Africa for a month on an internship with rhinos and elephants many, many years ago now, and a fellow intern in me were asking when we were gonna see some cool big cats. And they went, oh, the Hollywood animals, and kind of rolled their eyes and it stuck with me because yeah, we're drawn to the big, flashy, obvious stuff, right? But most of the time, the really important stuff in biology, well, it's happening somewhere smaller, quieter, easy to overlook. The water bears, the sea slugs that steal chloroplast. The bacteria that we borrowed horizontal gene transfer from to integrate into our newest biotechnology. The tiny things that quietly build everything. Okay. Now number two, I've started a substack. If you don't know what that means, don't worry. Neither did I. It's another platform where I'll be putting episode previews and all my sources and a seven to 12 question quiz after each episode, so you can test yourself if you want. I've already put up a 20 questions. Story so far. Quiz covering episodes one through nine at from sell to us.com. I'll keep the link in the episode description wherever you're listening, if you wanna check it out. And three on a personal note. Thank you so much for listening. If it weren't for you, I'd just be talking to myself, which honestly I'm fine with, but you know, with a script involved, that feels like it's crossing a line. So thanks for keeping me on the right side of that line. Also, a quick shout out to everyone who's listening outside the us. I see you in Vietnam, Egypt, Pakistan, the uk, Australia. And there's someone in Singapore who listens like right away every time I release an episode. It's amazing. I really appreciate it. Thank you. And a shout out to Ashburn, Virginia. There's a sizable chunk of listeners there that started at episode seven and has continued to tune in. So thank you. And the new locations that joined last week. The Philippines, Virginia Beach, Virginia Burbank, Illinois. And Van Nuys, California. Welcome. I hope you stick with us from cells to us has hit 33 countries and 137 US cities. I can't tell you how much that means to me. And truly thank you for joining me on this biological journey. I'm Jackie Mullins, and this has been from cells to us. How I'll see you next time.