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Main content
Current time:0:00Total duration:6:20
AP.BIO:
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SYI‑1.E.1 (EK)

Video transcript

what I want to do in this video is give an overview of the endomembrane system in eukaryotic cells endo endo membrane system and at a very high level the endomembrane system is all of the the membranes that interact with each other inside of a cell so what membranes are we talking about well you could start off by talking about the cell membrane itself and all of these membranes these have by layers of phospholipids I sometimes my brain malfunctions and I call them by lipid layers but these are by layers of phospholipids so if I were to zoom in right over here if I were to zoom in right over there that line it really is a bilayer a bilayer of phospholipids so it would look like this so you have your hydro hydrophilic heads pointing outwards and your hydrophobic tails pointing inwards so hydrophilic heads pointing outwards hydrophobic tails pointing inwards and it keeps going so you have if we think of it from left to right you have a layer of - or you have a bilayer I should say of phospholipids that's going to be true with a cellular membrane that's going to be true of this of the outer nuclear membrane right over here we drew this one on the video on the endoplasmic reticulum and so over here you see these two membranes you might say okay is this a bilayer no this is actually two bilayers so this membrane right over here is has a phospholipid bilayer and this membrane over here also has a phospholipid by a phospholipid bilayer this the one let me just in another color this one that I'm starting to starting to trace in magenta that's the outer membrane of the nuclear envelope and it's continuous it's continuous with the membrane of the endoplasmic reticulum which I'm starting to highlight right over here and then the one that I'm highlighting in this purple color in this purple color this is the inner membrane of the nuclear envelope and all of this is part of the endomembrane system so I already just I've already started talking about the endoplasmic reticulum and we go into some depth on that the video on the endoplasmic reticulum and the Golgi apparatus but it's also part of the endomembrane system and in the endoplasmic reticulum in particular can represent up to or even more than 50% of the membrane associated the phospholipid membrane associated with the cell and we've talked about what goes on in the lumen of the endoplasmic reticulum so this area right over here right over here we've talked about what happens there proteins can get synthesized actually other molecules like lipids can get synthesized there they can and then they can go to the smooth ER and then the place where they can exit from the smooth ER and we saw that in the video on the endoplasmic reticulum how they can kind of butt out we call this area it's often called the transitional ER so this area right over here we would call the transitional endoplasmic reticulum transitional transitional transitional transitional ER is this place where these proteins are being butted off and they're budding off in vesicles so this is the transitional ER and all vesicles are are little small compartments that have a membrane around it that things like a protein can be transported in and not you know I don't want to beat a dead horse here but all of these lines that I'm drawing even though I drew it as a single line these are phospholipid bilayers so the membrane might be different the phospholipid bilayers might be different when we go from one piece of the membrane to another but they all have that same general notion of having this this bilayer of phospholipids but just as a review these proteins they can they can they can emerge from the transitional ER they can make their way to the golgi apparatus and we've already talked about how in the Golgi apparatus these these proteins can be matured and when I say being matured there's a bunch of enzymes in here there's a bunch of Golgi enzymes in here that can do all sorts of things to the proteins tag them they can actually they can actually add add add saccharides to them so that they become glycoproteins they can tag them so they can be used in the cellular membrane or be used outside of the cellular membrane we used other places in the cell so for example this protein right over here butted off as a vesicle it makes its way to the Golgi apparatus the membrane can then merge and dump the protein into the Golgi apparatus from there it can be matured it may might turn into a glycoprotein who knows what happens to it and then it could butt off again and then this protein that's now butted off it could go to be embedded into the cellular membrane the protein could be excreted from the cell or it could go to other parts of the cell now those aren't everything I've just talked about those aren't the only parts of the endomembrane system you have things like vacuoles which are membrane bound organelles in a Cell in plant cells a vacuole can be used for storage it could be used for structure vacuoles can get quite large and they can actually give kind of the structure of the actual plant in animal cells in animal cells you might have something called a lysosome and a lysosome is a membrane brown structure where essentially things go to for the most part be be recycled or to be to be torn apart so you know maybe something got packaged from someplace this is some molecules over let me do this in another color you have some and I drew that vesicle a little bit too big but maybe this stuff it needs to be destroyed so this membrane is going to it can then merge with that membrane and dump its contents and then dump its contents in here and this has a very low this has a low pH and it can actually kind of break apart this stuff and it can digest this stuff and recycle in it into it's kind of I guess you could say more constituent material so all of this is part of the endomembrane system so once again whole figures you an appreciation for how complex and and a lot of levels beautiful cells can be
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