A Tour of the Cell

[Music] hi it's mr. Andersen and in this podcast I'm gonna take you on a tour of the cell we're gonna talk about the different types of cells and then how the structures inside a cell fit their function first thing though that we need to talk about is why cells are small reasons cells are small is the material moves into a cell through a process called diffusion so oxygen gets in that way and carbon dioxide is going to move out in the same way and so it would take a long time for material to diffuse into

a cell and so what we can do is we can actually make that volume the same but we can increase the surface area and now the distance that material has to move is actually relatively small and you also might think to yourself well why aren't they infinitely small why are they really really tiny well the reason why is that the material inside a cell the information inside the cell like the DNA and the machinery of the cell has to be able to fit inside the cell and so there's like a perfect sweet spot in size

for all the different types of cells that we have another thing I want to talk about is cells are not boring that when I grew up I had this idea that a cell was like a bag of jelly and yet stuff like a nucleus inside and it would essentially float around this is probably perpetuated by biology teachers always an assigning like an edible cell assignment and if you actually look inside a cell it's incredibly complex they have this cytoskeleton that's made up of a number of different macromolecules it's like a lattice inside the cell and

all the organelles fit within that lattice and it works almost like a monorail as materials moved around on this monorail using these motor proteins and I'm not joking they literally walk like that on the on the monorail and so they're incredibly complex cells are but they're oftentimes misunderstood and they were totally invisible to scientists until we invented the microscope in other words we couldn't see in them if you look at your hand you can't see the cells and and scientists couldn't see him either so they didn't know what was going on until they discovered it

and invented the microscope um comes in two different types you basically have optical microscopes and then electron microscopes optical optical microscopes use light and lenses to magnify the image if you've ever used binoculars and then you turn it upside down and hold it close to your hand you actually have a real simple microscope and so that's the way that they work if it's an electron microscope what they're using is a number of magnets and those magnets will be used to focus electrons either through an image or bouncing it off an image so we got transmission

and scanning electron microscopes how does this work well a quick demo would be to take a big magnet and hold it really close to an old television or your computer screen don't do this if you were to do it it would permanently ruin your monitor or your computer screen but basically what it's doing is the magnet is changing the path of the electrons and by doing that we can actually increase the magnification on the specimen so here's some pictures that were taken with these this would be a Paramecium with an optical electrical microscope one that

you have in a typical biology classroom these ones are taken by a transition transmission electron microscope these are little viruses or this would be an ant that you're looking at now these two are dead because of the material in order to look at it the process is actually going to destroy it and in fact it here you have to put a thin layer of metal on it that we can bounce it off on is on a scanning electron microscope and so the future is electron microscopes but it's also what are called the fluorescent optical microscopes

so we're coming up with these beautiful fluorescent dyes you saw one on the first page in this podcast and that we can stain material that can stay alive even so I once named this last summer that was a live dead State and so you would stain it and it would show you all the cells that were alive at that point and dead at that point really cool we're getting some great visualized visualization of the cell thing you should know is there are two major types of cells we have ordered are called prokaryotic cells and then

eukaryotic cells prokaryotic cells are going to lack a nucleus there before the egg if we break down that word so there's gonna be no nucleus eukaryotic cells are gonna have a nucleus what types of things are prokaryotic really only two things bacteria are gonna be prokaryotic and then the archaea bacteria only try to spell that correctly are going to be prokaryotic eukaryotic are gonna be things that you think of as alive that aren't microscopic things like plants animals fungus protists things like that that are really really large and the scale is bad here because if

I were to scale it right the protists or excuse me the bacteria to be about the size of this mitochondria so these are really really small but there are some similarities between the two in other words all cells are gonna have nucleic material so they're gonna have DNA all cells are gonna have a cell membrane around the outside some form a cytosol on the inside and they're also gonna have ribosomes man they may differ but all cells are gonna have those things as we move to eukaryotic cells let me go back again then we're gonna

have organelles so we're gonna have organs within the cell that you're familiar with like a mitochondria I'd be an example of that and so basically prokaryotic cells are simpler I'll talk more though about them when I talk about bacteria but most of the time in this podcast I'm going to talk about eukaryotic cells this would be an animal cell I can tell right away and so let's kind of look through an animal cell so basically these are the major organelles that are found within a cell from the nucleus all the way down to the centriole

and so what I'm gonna do is go through it show you where they are talk about what they do and then you probably want to review at the end and go through all of them and see how much of the information that you actually picked up so let's start with number one and that's the nucleolus nucleolus is gonna be found within the nucleus and I used to be confused on how this actually works what they do is all the chromosomes that are within the nucleus what they do is they put all of their genes to

make ribosomes in one area within the nucleus and that as a result since we have a lot of proteins inside here is going to be a little darker when it gets stained and so this is an area where the chromosomes are all producing ribosomes to make the ribosomes gonna be right there it's kind of a two-step process so basically what happens is in this area they're gonna produce ribosomal RNA it'll roll out here to actually build some of the proteins using ribosomes outside of the cytoplasm then those proteins will move back where we assemble the

building blocks of proteins which are going to be ribosomes so I talked about a lot of different things but what did I mean to talk about well the nucleolus is an area where the ribosomes are assembled inside the nucleus if we go to the next one next one's going to be the nucleus and that's one of the first organelles that was ever discovered there's a beautiful fluorescent dye on the nuclei so what's the function of the nucleus well when I grew up I always heard it was like the brain of the cell that's really over

oversimplifying it what's inside here basically we've got DNA so the genetic material of the cell is gonna be found inside the nucleus and that's gonna determine you know what kind of a cell it's gonna become but it also is gonna control the cell in other words we're gonna make proteins we're gonna make enzymes at a certain time and as a result of that cells gonna do something and so if you still want to think that it's the control center of the cell that's okay but a better way to think about it it's just where the

genetic material is and it's also going to have little pores on the outside that'll become important when we start talking about transcription and translation so they're gonna be little holes on it and that's how material can move out and material can move in through those little holes okay next we get to the ribosome ribosome generally growing up I represented those as little dots inside the cell it's a little more complex than that the two parts of it you're gonna have a small subunit on the bottom you're gonna have a large subunit on the top and

the messenger RNA is gonna move through that and then on the top we're gonna bring in the transfer RNA and we're actually going to build our protein off of it and so the function of the ribosome is going to be to build proteins and prokaryotic and eukaryotic have different ribosomes and that's how some of our antibiotics actually work vesicle is a broad term vesicle basically means a membrane bound container and they're really really small and sometimes they're really really big so a vacuole of the example of a vesicle and they move material around depending on

what they do like a trans vesko would move material around next we get to the level of the rough ER the rough endoplasmic reticulum it's actually a membrane that's that is continuous with the nucleus and so we've got this folded membrane that comes out from the nucleus you then have ribosomes that are sitting on the outside of it that's why it's called rough ER I like to think of this as the factory inside of a cell and so basically what you're gonna have is this membrane so we've got a membrane like this and then you're

just gonna have a ribosome that sits on the top of it and so basically what you can do is as the messenger RNA comes through we can make the proteins that we want to make and so it's like a factory it's gonna be where we make the material it also produced the membranes that are gonna be used within the cell next we get to the level the Golgi body I like to think it looks kind of like pita bread that is folded on top of itself so if we were to say where are these proteins

going they're going to be created in the endoplasmic reticulum they'll then be packaged in a little transport vesicle and move to the Golgi apparatus at the Golgi apparatus we're going to modify that we're gonna add things like carbohydrates to those proteins we're gonna snatch them up a little bit and then we're gonna send them on their way so another way to think about that is it's like a UPS in other words it is a shipping part of the cell things come in as a transport vesicle they're gonna go out as a transport vesicle and they're

gonna go where they need to go within the cell next we got the cytoskeleton cytoskeleton is the structure inside the cell it actually gives it that physical structure as it move as L were to move around that's gonna have to be like an amoeba that's going to do too with the cytoskeleton as well the way I like to think about this is through analogy so it's kind of like a bridge so on a bridge you're gonna have two things those are going to be supporting the bridge but then you're gonna have these really thin wires

that attach it up like on the Golden Gate Bridge and so basically inside a cell we have those two things we have the big things those are called microtubules and they're made from protein called tubulin and then we have these really thin things and those are called microfilaments and what what the what the big things though microtubules do is they provide compressional support just like the weight of the bridge is supported by them and then those thin microfilaments are going to provide attentional support and so if you think of a cell like the Golden Gate

Bridge but kind of inverted inside it that's a good way to think about it what a cytoskeleton is next we get to the smooth ER what's it missing ribosomes what's it producing is going to produce a lot of the lipids cholesterol things like that in the cell it also is really really important in detoxification so breaking down toxins and so if you're an alcoholic hopefully not but if you're an alcoholic basically the more you drink the more your body's gonna build up smoothie or it's inside its cells so you're gonna have to drink more and

more and more and more next we've got the mitochondria mitochondria you know is the area where we're gonna generate energy what's is really generating that's gonna be ATP in the form of ATP it basically has a folded membrane inside a membrane it looks a lot like a bacteria and that's because scientists think that they became parts of ourselves through endosymbiotic theory in other words they became parts of the cell they produce ATP for that cell and then they get a place to live what's some evidence for that well they have their own DNA they produce

on their own through binary fission and so it's pretty much accepted as biological fact now we have the vacuole vacuole is gonna be something that we find inside plants not in animals generally large vacuoles and in this plant cell here what it's doing is its it's storing water and so it stores that balance and pressure that turgor pressure that keeps a cell properly inflated some protists will actually have a contractile vacuole that can pump water out when they're living in a freshwater environment as well we've got vacuoles but they're really small in general and animals

and they're used for like endo and exocytosis next we got the cytosol the cytosol you can think of as like the dissolved material so it's the fluid but it actually contains solutes inside it we used to think that was about it but what we're finding is their concentration gradients within the cell and so even the cytosol itself is pretty complex next we go to the level of the lysosome the lysosome is going to be sometimes it's been coined as like the suicide sack what does it really have inside it it has these digestive enzymes inside

it and it's contained within this membrane and so basically what we can do is we could have that go next to another vesicle that has material that we want to break down and those of enzymes I'll go in there and it'll break it down or where it gets his name from is if we were to pop this lysosome basically what happens is those digestive organ digestive enzymes would go throughout the cell and would kill the cell dissolve the cell and so the process of apoptosis is where it cell kills itself is a product of lysosomes

and finally we have the centrioles centrioles part of what's called the centrosome and basically it's important in positioning within the cell so dependent upon where the centriole is it's also going to set up where is the nucleus going to be and where the other parts of the cell going to be it's also important as a cell divides it's going to be as it migrates to either side it's going to initiate the formation of the spindle and the spindle is going to be attached to the chromosomes and gonna pull it to either side and so we

have those but if you're looking the higher plants that's we they don't have centrioles and their role is somewhat undefined and i think we could say the same thing for all of these that we really have an idea of what they do but they probably do lots of other things that we're really not familiar with and so this is where the podcast becomes scary I'm going to make all those terms disappear and basically if you hit pause could you go through at the beginning and list you know what is number one what is number two

what is number three what is number four what is number one do and if you can't do that you really don't understand it and working with kids in class what I found that when you're trying to learn the parts of the cell sometimes it's easier to just build some flashcards and go through the flashcards because if you can't get it right now then you don't got it and so that's the tour of the cell and I hope that was fun and I hope that was helpful