Eukaryotic Cell Architecture

Hi in this video we're gonna be talking about eukaryotic cell architecture. So this video is dealing with eukaryotic features. So eukaryotic cells are classified by a few distinct features. Now you can see there's a lot of molded words behind me. But you know all of these terms. These are all terms that you've gone over in your intro bio class and I'm just going to review them here so we can just all refresh and be on the same page of what defines a eukaryotic cell. So the first thing is that a eukaryotic cell stores its D. N. A. In a nucleus. Um that is enclosed by a double membrane terms the nuclear envelope. Now this nuclear envelope within it contains nuclear pores which allows for the nucleus to interact with things outside of the nucleus. So things get transported between the pores and it also contains or at least inside the nucleus contains a specific area called nuclear Y. And this is where ribosome synthesis occurs. Now remember ribosomes are important for gene expression and protein creation. So you carry out its cells have organelles. So they have these internal structures where different types of processes happen. And all of them are membrane brown. So they have these internal structures that are enclosed with membranes. They also contain sido skeletal structural components. So these are different types of proteins that really provide mechanical support to the cell just so it doesn't collapse in on itself. Um And they all like all other cells have a plasma membrane to separate the intra inner of the cell and the extra cellular environment. So like all membranes, this is formed by a lipid bi layer which if you remember, is made up of lipids that both can interact with water and one portion and not interact with water and another abortion. So this is called an to fill it and am empathic and telepathic. And then um each of the terms. So if the part that can really interact with water is called hydro filic in the part that can't interact with water is called hydrophobic. And so like in the nuclear envelope which contained nuclear pores to allow the cell to allow the nucleus to interact and transport things between the nucleus and the external environment. The plasma membrane also has membrane proteins that allow the cell to um interact with the interim exercise of the environment. So here's just a very very very simple drawing of eukaryotic cell. You can see that it has a nucleus. This is pointing specifically to the nuclear Olas. Here with this entire structure in blue is the nucleus. And you can see this orange one here is actually the nuclear envelope separating the nucleus from the inside of the cell. Now, all throughout the cell you have these compartments here's one, here's one, here's another, here's one and all of these are organelles that are brown by membranes and then um all cells including eukaryotic cells have a cell membrane the plasma membrane. Remember the lipid bi layer um that allows the cell to interact with this extra cellular environment. So now let's move on to the next concept.

So one of the common feature of eukaryotic cells is that they all contain organelles. So eukaryotic cells contain numerous membrane bound organelles, Each with a different function. Now you've already gone over these organelles many times beat them to death and by 1.01. So I'm just gonna refresh them here. We're gonna have an image of them at the end. But if you really need to you feel like you just don't have it down you need to know these um these are important for cell biology. So I suggest yes that this review isn't enough. Let's go back to your notes, go back to your textbook, go back to some of clutches videos on in the intro bio class and really review the purpose and function of these different organelles because it's crucial to understanding cell biology. So let's just review them here. Maybe you'll feel refreshed at the end of the like. Oh yeah I got this. So the first one is the endo plasmid particular and this is where proteins are synthesized and then exported to other compartments. So there's two main types rough and smooth and the reason that they are called rough and smooth is because that's how they look under the microscope. So rough is the place of protein synthesis which for protein synthesis to occur needs a lot of ribosomes and ribosomes make it look rough, make it look like it has an uneven appearance under microscope. Whereas the smooth er ectoplasmic particularly are short for that. It's actually a place of lipid synthesis. And so it doesn't need those ribosomes so it doesn't have them and appear smooth. Now the second one is the Golgi apparatus. So this is where once the protein's been synthesized in the er and then goes to the golgi if it needs to be modified, sorted, transported or secreted. So if a protein needs to get somewhere in the cell or needs to be secreted it's gotta go through the golgi. Now the next to our mitochondria and chloroplasts which are kind of unique um organelles because they're really responsible for producing energy. So their mitochondria I'm sure you've heard is the powerhouse of the cell. And this is because it produces a G. P. As an energy storage molecule. And mitochondria actually contain their own D. N. A. In their own ribosomes. Which is a very unique feature of organelles. That's other than chloroplast is the only organ l that actually can do that. So chloroplast is actually a location of photosynthesis meaning that chloroplasts aren't in cells. Humans don't have chloroplasts because we don't photosynthesize. But anything that photosynthesize is including plants and some types of algae have chloroplasts. Um And here this is again it produces these organic molecules sugars um that are responsible for the self survival. It also like the mitochondria contains sienna rib ISMs. Now we start getting to these I'm sure you're familiar with those but now we get to some of these lesser known organelles these are licenses OEMs which are responsible for intracellular digestion. So if something needs to be broken up, it's sent to the life zone, then we have peroxide zones, which is actually just kind of this really interesting organ l so if anything really harmful, like a harmful chemical reaction needs to occur. If it occurs just in the side of saul within the cell, it could really damage some organelles or proteins or something that the cell needs. So instead the cell says, okay, we're just going to put all these harmful chemical reactions into a proxy zone. So um one example of this is, you know, the formation and breakdown of hydrogen peroxide which the cells occasionally need to do and when they do they just put them in proxies zones and say, okay, you're harmful. I'm in a story you hear now another um organ al is called a vacuole and this is a place for temporary storage. So you're probably most familiar with this in plant cells. Um because plant cells contain a single large vacuole that stores water and this is what gives plant leaves, it's really strong structure. Um and that's called turker pressure, the water pressure that allows the cell to or it allows the plant to remain sort of vivacious and up there and when the water is out of the vacuole is sort of wilts. Now vesicles are important. Organ L and they transport cells to other locations. So you remember back the golgi apparatus sort of processes proteins and gets them ready and sorted to their different locations, but vesicles are actually what carry them there. So if something needs to get to another part of the cell or secreted, it's got to be carried there through a bicycle. So this has major roles in endo psychosis, which is entry of products into the cell or exocet Asus, which is exit of materials outside of this home. Now, cellular organelles. And before I actually fill in this word, I just want to say this is important because people really confuse side us all inside of plaza and they say, oh those are the same things but they're not. So how they're different is that cellular organelles are suspended inside us all. So any type of, you know, this acquis gel material in a cell that's not in an organ l is called side of saul but um there's a lot of this gel inside of the organelles as well. So um the cytoplasm is the total of the liquid that's inside and outside of organelles. So these are different. So the side of saul is not an organ, I'll cytoplasm is inside and outside of organelles. And a ton of things happen in the side of saul, that's where things are moved. Um it's where protein and lipid synthesis can occur and so many different chemical reactions occur in the side of saul and also in the cytoplasm. So um here are really two images that I want to show you. So the first is from here over and this is this huge sell um this is a eukaryotic cell obviously and it has all these different organelles. Now there's a lot of there's a few things we haven't talked about yet, mainly in here. Um but it's really important that you see the nucleus, not necessarily these but you'll see as you go through you have the plasma membrane, the golgi apparatus, the rough and smooth er um you don't necessarily need to know acting filaments now but you have the proxy zone license um ribosomes, mitochondria and these are all compartments of the cell and so they are um really crucial that what makeup eukaryotic cells um and are necessary for eukaryotic cell function. Now the second one image on this side is talking about the difference between the cytoplasm and the side of sol. So cytoplasm is made up of the side of saul and the gel inside organelles. But the side us all is just gel outside of organelles. They're not the same. Really important to keep that in mind when we use these terms in the future. So now let's move on to the next concept

So in this video we're gonna be talking about the eukaryotic origins. So multiple theories exist about how about the evolution of eukaryotic cells. So first and I think the basis of really all of the eukaryotic features is through this idea that before they're eukaryotic cells there were all of these pro Karadzic cells of different sizes existing. But eventually these larger um pro chaotic cells began taking up these smaller ones. So really these eukaryotic cells eventually evolved from predatory pro carry out ICC cells. So they sort of consumed the smaller ones. So this first gave them a larger size because of these larger pro chaotic cells are eating all of these are consuming all of these little small ones. They have to get bigger because they have to be able to take up all of these small ones. So first it gave them the south sides but then it also um this predation gives a foundation for what we also termed the endosymbiont theory. And that explains actually the presence of organelles like mitochondria and chloroplasts. So um mitochondria and chloroplasts are unique. Organelles they actually contain their own D. N. A. Which suggests that at some point before they became organelles they were actually these individual organisms. Um And so through this predation process eventually one of these smaller cells that was taken up um decided not to be destroyed sort of stayed there was able to survive and eventually evolve over time to become the organ L. And so what you can see here in this diagram you have this bacteria which remembers a small pro carry out excel. And this right here is a much larger pro periodic sell. Now this large one is consuming right here this small one and eventually over time it is able to remain inside the larger pro cryonics. L. And evolve to become what we now know as the mitochondria. And this is how it's thought that chloroplast also evolved. So this is called the endosymbiont theory. Um the idea of this evolution of mitochondria and chloroplasts and eukaryotic cells. Now one of the things that is currently unknown is whether this large pro chaotic cell was originally a bacteria or an arcadia. Um So are eukaryotic cells derived from bacteria Archaea. We actually don't know. Some people have very strong opinions on it but um right now it's just unknown. So now that we talk about the origins, let's move on to the next concept.

So this day we're gonna talk about structural features that allow for the support of and transport of various materials in the cell. So you carry out its cells are supported through a complex structural system. So the three main components of this um you've already heard about really in your intro class, I just want to review them. Um So first is that first our micro tubules and these are hollow cylindrical proteins that are responsible for motility and cell organization and shape. The second are micro filaments which sometimes are called acting filaments. And these are thin, they're polarized, which if you don't know what polarized means, it just means that the two ends are different. So one end doesn't look like the start of the acting filament is different from the end of this acting filament and that the proteins, these acting filaments are really responsible for muscle contraction. And then the third type is intermediate filaments which provide a stable scaffold for cell structure. So you can kind of imagine these um as really the construction um scaffolds for big construction project is that they really provide support um for the cell. Now these um three structural features do a lot for the cell. One thing that they do is they provide a framework for internal transport. So things in the cell are constantly moving their dynamic, they need to get to one place to another and and these structural features allow for that transport to happen. So for instance, motor proteins transporting vesicles containing important chemicals or macro molecules across the cell um they use these structural features and they also provide the mechanical support for cell division. So there's a lot of movement of the cell when the cell divides, you have all these different organelles, these chemicals and the D. N. A. Going all of these different places um into the two daughter cells and eventually those daughter cells have to actually split from one another. And so the really crucial uh features of a eukaryotic cell that's responsible for this are these structural features of the micro tubules that act in filaments in the intermediate filaments. And then they also which I don't have written down here, but they also just help the cell survive and not collapse in on itself provide support and the basis for life. So I really love this image. And I hope you do too. I like it when I can actually see um real live cells doing something cool. Um So this is real life cells. Um and these are the side of skeletal structures. So you can see acting filaments are in red. So here acting, you see really along the edges here and then you have micro tubules are in green which you can see them throughout the cells here. I grow too. And I think this is really neat um because you can really see that these compartments are throughout the entire cell. Now. There's another feature here which I didn't mention. Um It's blue. Um And this is just the nucleus. And usually in these images you'll see the nucleus are colored and blue. Um So the structural features are throughout the cell, and they have a lot of important functions in eukaryotic cell biology. So now let's move on to the next concept.

in this video. We're gonna be talking about eukaryotic genetic features. So eukaryotic DNA structure and storage allows for tight control of gene expression and cell division. Let's talk about how the D. N. A. Is stored. So eukaryotic DNA is formed into linear chromosomes which I'm sure you remember this is what they look like here. Um These chromosomes and they're packaged by histone proteins. Now you probably never heard of histone proteins which is fine. You don't need to know them right this second we are going to be talking about them a lot later. Just sort of know histone proteins exist and they have something to do with D. N. A. So chrome button which is a term you might be familiar with and should know and that is the combination of D. N. A. And histone proteins. And so why do why does the DNA need to actually interact with the proteins? Why does it need to be packaged? Because it needs to is because the genome is freaking ginormous. I mean it is huge. It wouldn't fit into the cell if it wasn't packaged. And this is because the eukaryotic genome contains these large stretches of D. N. A. Um that really just has this unknown function. It doesn't make any sense. It doesn't code for proteins. We don't know what it does. And so because of this it makes the genome really huge and so it has to be packaged in order for it to be able to fit into the cell. So um D. N. A. D. N. A. Storage stored in these chromosomes and packaged that way. But gene expression is controlled by physically separating the location of transcription and translation. So transcription occurs in the nucleus and translation occurs in the cytoplasm. Now um the fact that we have these two separate compartments where transcription and translation occur is important because that's what allows us to really control gene expression. So if something gets transcribed and it's not supposed to be well it's not going to get exported to the cytoplasm then it can't be translated. It can't exert whatever function that it wasn't supposed to exert super important gene expression control. Now just as a reminder about eukaryotic cell division it has these different processes where it can result in genetically identical cells and that's termed mitosis or genetically similar but not identical cells and that's called mitosis. So if we look back here at this image we can see that um you can see first the DNA double helix which we're familiar with. But then you also see chroma tin which you remember is the D. N. A. Which here is in blue but also these green proteins and these are the his stones some proteins. Now there's other things that were not necessarily going to focus on right now. But then eventually this is packaged into a chromosome which is a structure worth familiar with. So this is how DNA is packaged. So let's now move on to the next concept

this video we're gonna be talking about multi cellular structure. So eukaryotic cells are unique in the fact that they can form these multicellular structures and these organisms. And so because of this, they have to be able to connect cells together in some way so that they interact is one unit instead of all these different separate cells. So one of the ways they do this is to the extra cellular matrix which attaches cells together and provides extra cellular structure, which makes sense extra cellular matrix, extra cellular structure. And so generally this is made up of proteins. Um If you want to know the specific names, they're called collagen and protein glide Ganz, but you don't need to know the exact terms, just know that it's made up of proteins. Um and it attaches cells together, but a really important feature of it is that it's not rigid and instead it's flexible, allowing for movement of cells or organisms. So the fact that we can move and I can move my hand right now is due to the fact that the cells that are connected in my body making up my hand and my elbow. These cells are flexible. They're not rigid and they have the ability for movement. The extra cellular matrix is really important for providing that flexibility. Now plant cells are a little bit more unique because they have cell walls and their cell walls are actually really rigid, which is why plants don't move as much. Um but they still have to be able to connect cells together and interact as a whole organism instead of individual cells. So one of the ways they do this is through a structure called plasma Dis Mata, which forms the cytoplasmic bridges between cell walls. So let's actually look at these. So this here is an example of plasma does Mata down here and you can see there are these small structures, these tunnels almost between the cell walls of plant cells and they connect the cells together and they connect through these cytoplasmic bridges. Now groups of cells together can act as one and this actually allows for the evolution of multicellular so different types of tissues and organisms which is also referred to as cell differentiation. So the ability of a cell one cell to turn into another cell and the presence of both of these different types of cells is due to the fact that they can connect, they can interact and they can have different functions. So I've already shown you the plasma does Mata. But what I want to show you here is this is really the extra cellular matrix which you can write as E. C. M. Um And it's made up of all these different proteins um down here that help to support these cells and connect them together as one unit instead of all of these individual cells. So now let's move on