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Main content
Current time:0:00Total duration:9:38
AP.BIO:
EVO‑2 (EU)
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EVO‑2.C (LO)
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EVO‑2.C.1 (EK)
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SYI‑1 (EU)
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SYI‑1.D (LO)
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SYI‑1.D.1 (EK)
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SYI‑1.D.2 (EK)
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SYI‑1.D.3 (EK)
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SYI‑1.D.4 (EK)
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SYI‑1.E (LO)
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SYI‑1.E.1 (EK)

Video transcript

what we're going to do in this video is give ourselves a little bit of a tour of eukaryotic cells and the first place to start is just remind ourselves what it means for a cell to be eukaryotic it means that the inside the cell there are membrane bound organelles now what does that mean well you could view it as set as sub compartments within the cell membrane bound organelles and in this video in particular we're going to highlight some of these membrane bound organelles that make the cells eukaryotic so let's just start with some of the ingredients that we know is true of all cells so you'll have your cellular membrane here a little bit big so that we have a lot of space to draw things in so this is our cellular membrane I'll doing that little nice shading so you appreciate that it'll actually be 3-dimensional we see so many slices of cells that sometimes we forget that they are more spherical or that they have three-dimensional shape to them they're not all spherical they can have different shapes now all cells and there are some exceptions that we've talked about in previous videos I should say most cells will have some genetic information in them in the form of DNA so that is our DNA right over there now one of the key characteristics of a eukaryotic cell is that that genetic information is going to be inside a membrane-bound organelle and that membrane-bound organelle or the membrane that binds or that surrounds the DNA here that is the nuclear membrane so let me draw the nuclear membrane right over here and I'll put some shading in to appreciate that that also is going to be in three dimensions around the DNA and so that is the first membrane-bound organelle that we're going to discuss the nucleus now the nucleus it turns out is connected to another membrane-bound organelle and we're going to study this in future videos but right here I'm drawing holes or pores in the nuclear membrane and those pores connect to something it's a very fancy word called the endoplasmic reticulum and the endoplasmic reticulum is essentially these layers of these membranes so I'm going to do my best job at trying to draw an endoplasmic reticulum imagine extending from these pores going into a space that has these really these layered membranes that have a lot of surface area and I'm not going to go all the way around at this nucleus but in many cells it will go around all all the way around the nucleus and this right over here and this is just a rough diagram that is our endoplasmic endo plasmic that's plasmic endoplasmic and no plasmic reticulum which I've mentioned in previous videos would be an excellent name for a band and what goes on in the endoplasmic reticulum is when you are in the process of taking that genetic information from DNA and as we talked about in other videos it gets transcribed into mRNA so that mRNA is now containing that information that mRNA will make its way out of that nuclear membrane through one of these pores and then make its way to a ribosome that is attached to the membrane of the endoplasmic reticulum and so that's a ribosome there I'm gonna do a bunch of ribosomes and so as we've talked about in previous videos the ribosomes are really where you take that genetic information from that mRNA and then you translate it into a protein so the ribosomes are the protein synthesis so let me label that so this right over here is a ribosome and some ribosomes might be attached to the endoplasmic reticulum some of them might just be floating out here in the cytoplasm so that would be a free ribosome free ribosome and even from the point of view of the endoplasmic reticulum the parts of the endoplasmic reticulum where you have ribosomes attached this is known as rough endoplasmic reticulum it's the ribosomes that are making them rough it looks that way in a microscope so I'll say rough ER for endoplasmic reticulum for short and then you also have parts of the end up particula where you do not have ribosomes attached and because that looks smooth through our microscope it has been called you can imagine smooth endoplasmic endoplasmic reticulum there are things known as Golgi bodies once again another fascinating name you've got to love these names in biology that look kind of like an endoplasmic reticulum but detached from the nuclear membrane so let's say it's something like that that's my best drawing there that's a Golgi body and these are really good at packaging molecules even proteins that might have just been produced and packaging them so that they can be used outside of the cell for example so and we'll go into detail in other videos where a protein might go to the Golgi body get a little envelope around it get some little processing going on and then make its way outside of a cell now another and this is maybe one of the most famous membrane bound organelles outside of the nucleus is what's known as the powerhouse of the cell and that is the mitochondria and so I'll do the other this mitochondria and magenta cuz that's a nice powerful color so mitochondria and I love mitochondria because it's fascinating how they even came to be mitochondria actually have their own DNA and all of your mitochondrial DNA come from your mother and so that's actually very interesting for tracing maternal lineage but mitochondria this is where you're I'm gonna say let's see we could see inside of this this is where your ATP is produced this is your mitochondria it's really the powerhouse of the cell what's interesting about mitochondria is evolutionary biologists believe that the ancestors of mitochondria because mitochondria have their own DNA they might have been independent organisms independent cells and at some point in our evolutionary past they started living in symbiosis inside of what will what would be the ancestors of our cells and it over time they became so codependent that they started to replicate together and mitochondria in fact it became part of these eukaryotic cells now if this eukaryotic cell was a plant cell or maybe an LG cell you would have something called chloroplast there we don't have them because we don't have photosynthesis but this is a chloroplast if you could see inside you could see the little thylakoid stacks right over here you could see the thylakoids if you could see inside and so this right over here is a chloroplast chloroplast and this would be plants and algae animals do not have these and these are where you have your photosynthesis take place photo synthesis now there's also some other membrane-bound organelles that are maybe is less famous than the mitochondria or the chloroplast or for sure the nucleus and that might be something like a vacuole and in plants vacuoles tend to be very big I could draw it you know this is three dimensional so I'll draw it on top of some of what I've drawn before so if a vacuole right over here this is a in a plant could be a fairly significant compartment inside in fact it can even give structure to the plant itself because it is so big and it contains water and enzymes it's viewed as a kind of a storage compartment but it can also contain enzymes that help digest things that help break things down so that they can be used in some way so that is a vacuole and they don't just exist in plants they can also exist in animal cells but in plant cells they tend to be they can be very very very visible now something that is somewhat related to some of the function that a vacuole plays that are most associated with animal cells but now there's evidence that they also exist in plant cells is the idea of a lysosome so a lysosome right over here that also is a compartment and it's going to contain a whole series of enzymes in it that is useful for licen you could say that is useful for breaking down either waste products as the cell lives or even foreign substances that might not be helpful for the cells so it's going to contain a bunch of enzymes and it helps break down things now I'll leave you there these aren't all of the structures and eukaryotic cells but these are enough of the structures so that you can appreciate that there are a lot of membrane-bound organelles in eukaryotic cells and to be clear even if I were to show all of the membrane-bound structures that's not all the complexity of a cell the big thing to appreciate is cells are incredibly complex there's all sorts of structures in here that help transport things and move things around if you could shrink yourself down and look inside of a cell it would look more complex in the most complex cities there's all sorts of activities things being moved around shuttled around the cell itself is replicating and copying things and so this is just the beginning we're just starting to scratch the surface at the complexity of the most basic unit of life
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