Hi in this video we're gonna be talking about goldy processing and transport. So in order for proteins to get to the Golgi they first have to leave the E. R. So this is what this video is gonna be about. So um when proteins leave the are they automatically just end up at the Golgi for the most part not everything but most proteins that leave the er end up in the Golgi. And so in order to leave the er they have to be transported out in vesicles. And so the vesicles that actually are going to transport proteins um that are marked for exit from the er and entrance into the golgi by some type of sorting signal. Um These vesicles are called cop to vesicles and that means they have this protein coat for called COP two. And we're gonna go over different types of protein coats and different lessons But just know right now that in order to leave the E. R. And travel to the gold. The they have to transport out through vesicles now. Only properly processed proteins can exit the er for the golgi. So if the protein is unfolded right? If it doesn't look right it's not going to leave the E. R. And the reason is is because chaperone proteins um can come in and they control that folding um And then improperly folded proteins are going to be transported out of the er usually through some type of misfolded protein response or unfolded protein response and left up to the proteus um to degrade them. So if the protein wants to get to the gold it has to be processed properly Now, once it's packed into a testicle it's properly folded, the protein wants to arrive at the Golgi. So that is going to depend entirely on vestigial fusion. Right? So the protein is in the testicle if it wants to get into the gold it's going to have to fuse. So this type of fusion is given a special name, it's called hedorah typical fusion and that is going to be membrane fusion from two different compartments. So the two compartments here are gonna be the er and the Golgi which are going to have slightly different membrane components in them. So it's called hetero typical or you know different types of physical fusion. Now there is this interesting thing that can sometimes happen and I have it here i italicize because you don't necessarily need to know about it but it is interesting and you may read about it and that's called vesicular tubular clusters. So these are actually er vesicles that fuse together to create a big compartment. So these are tiny vesicles that you know add on each other. Make this large er vesicles compartment that will then fuse with the golgi delivering all of its content at once instead of in little spurts throughout between all these different vesicles. So what happens if a protein that wasn't supposed to leave the er actually gets transported to the gold while the these proteins contain retrieval sequences that direct them back to the er If they leave an example of this is a sequence called K. Dell and that KL is just like a tag that says I'm not supposed to be here. Please tell me, please get me back home. And that home is the er so they get directed back to the er through different types of vesicles. So here we have um this is gonna be the er here and we have our gold G. And you can see that there's hetero typical fusion where these little tiny vesicles all go and they're all going to individually fused. And then you have these vesicular tubular clusters which start out as little um vesicles but eventually fuse together with other ones to create this large compartment that will fuse to the golgi. So that is how proteins leave the er and arrive at the golgi. So now let's now turn the page

So in this video we're gonna be talking about what the golgi looks like. So the Golgi complex, you may also see it as the apparatus has a distinct structure that is made up of these flattened membrane enclosed stacks. Um And so each one of these stacks is called a cistern. And they make up the gold G. So there's about 3-20 um per gold deeper. And that number depends on the cell type. Some have more, some have less. Now the gold is gonna be ordered into three sections. You have the cis golgi which is going to face the er you have the trans golgi which is going to face the plasma membrane and then you have the medial golgi which sits in between them both. So if we look here, we have our cysts which is going to face the er So this is a vesicles that's coming in from the er then we have our trans face which is going to face the plasma membrane. And here these outgoing vesicles that are going somewhere out. And then in between here we have our medial and each one of these zac's here, it's called a cistern. So this is the weird blubber ish looking goldie. So with that let's not turn the page

Okay so now we're going to talk about um glad constellation and other protein modifications that happen in the Golgi. So for a protein that wants to get out and do something it's gotta look pretty. So that first starts in the er say with its makeup and then it goes to the Golgi to do its hair. And so the Golgi complex is a major location where proteins are modified. So the first modification I want to talk about is the first one that we talked about in the er and that's gonna be like oscillation. So glide consolation remember is the addition of carbohydrates. Um And it can occur in two forms on proteins and these forms are modified and created in the Golgi. So the first is going to be in linked glide consolation and that is when the sugar is linked to a nitrogen atom so that's going to be an in and then you have linked like oscillation which is going to be added to a hydroxyl group which if you remember what that is is an O. H. 00. Length. And notice also as well that these have been on different amino acids although you don't need to know which amino acids they happen on. Not for cell biology anyways and so protein like oscillation is important for protein folding and stability. So here's your to form so here's your in linked you can see is added here and here's your link which you can see is added here. Um So you have your glide constellation added onto these different amino assets. So there is a term called terminal glide consolation and that is going to be the final modification that happens to glide oscillation. So remember glide consolation all starts out the same way it all starts out with its foundation but all these different modifications can happen to it so that it creates all these different sugars on these proteins. But there is a final one that happens and it's called terminal black oscillation. And this final one occurs in the Golgi. So once it leaves the Golgi it's not going to have any more modifications done to it. So it needs to make sure it finishes it here. So for instance one terminal glide consolation that happens is for in terminal glide consolation that's going to occur in the er and it removes glucose and mono sugars in the bulging. Now you don't need to necessarily know this just know this, this happens here. And so there are some enzymes responsible for this. I've italicized them in case you read about them and I'm just wondering what these do. But these are the enzymes responsible for this modification. Now proteins undergo a lot of different modifications in the Golgi and each modification occurs in a different sister in a location or region or whatever you want to put here within the Golgi. And so each one of the Golgi regions there are functional differences. So the cysts does different things in the trans which does different things in the media. So here we have protein modification. So remember this protein is going to start out here in the er but eventually it gets transferred to the Golgi. Um So this whole thing here is the Golgi and you can see that modification. So it starts out with all these different colors and ends up with these um These modifications are happening in the Golgi before they're transported to the plasma membrane. So the golgi is a major place for protein modification with that. Let's now turn the page.

Hi, So in this video we're going to talk about goldie maturation and protein transport. So so far we've been focusing specifically on getting protein through the Golgi or what happens to proteins when they're in them. But we need to really spend some time talking about how proteins actually travel through the golgi because it has a unique way of traveling. So there are two ways that proteins can move throughout the Golgi. The first is called the vesicular transport model, which means that those Golgi cistern, we talked about don't move, they're just completely stationary, they're always there. And instead what happens is that a protein that needs to travel through the Golgi will do so in little vesicles. Now, there's another model that says cistern, a maturation model and this means that the cistern themselves actually move up so they travel up and eventually it gets to the point where it becomes the last one and then that last one will but off into a bunch of different festivals And it is eventually replaced by the one below it. And so um scientists aren't actually sure you know which one of these is more used, but it's there's been this really hot debate over which one of these happen. Um and so, but current evidence suggests that the proteins actually move using a combination of the two pathways. So let's look at both of these pathways. So here you have the cistern a maturation model. So what you have here is that the cistern themselves are moving. So these are these green arrows here. So these are being transported this way, the entire cistern until it reaches the end and these but off into all these different vesicles and it's replaced by the one below it. Then you have a vesicular model where the cistern a actually don't move so there's no movement here. But instead what you get is you get vesicles movement in between the cistern A that transport proteins throughout the golgi and so it's actually currently thought that both of these methods are moved differently by different proteins. So um protein transport between different organelles in the cell and the golgi occurs in two different ways. This is going to be between organelles. So the first one is called um and interrogate raid transport and that moves um from the er to the Golgi and towards the plasma membrane. So this moves outwards. Then you have retrograde transport which moves the opposite deray. So this is going to move inwards. So this starts at the plasma membrane goes to the Golgi and then goes to the er So in both of these processes, the Golgi acts as a sorting hub. It recognizes sorting sequences and it says okay you're going into this festival because this festival is going to the er where you're going into this festival because this festival is going to the plasma membrane and so there are a bunch of different protein receptors in the golgi that bind these sorting signals and trigger these proper sorting into different vesicles. So here we have the two different types of transport. So, like I said, this transport here is going out out and this retrograde transport here is coming in chew, chew, chew. So those are the two ways that proteins move between the golgi and other organelles. So now let's move on.