Understanding the Structure and Function of the Golgi Apparatus

foreign what's up Ninja nerds in this video today we're going to be talking about

the Golgi apparatus we'll go over its structure and function before we get started if you guys like this video it

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enjoyment also you want some notes illustrations to follow along with me go down in the description box below take

you to our website where you guys can check all that stuff out but Golgi apparatus what is the structure so it's

a really cool structure it's one of the organelles inside of the cell so at this point we've obviously talked

about the nucleus we talked about the endoplasmic reticulum those are all organelles the Golgi apparatus is a

really cool organelle now when we talk about this I like to think about its structure as though it's kind of like

this folded membrane right so it's this kind of like folded membrane if you will and there's a couple different anatomic

or structural points that you need to know so here we have the nucleus right so here is going to be the nucleus we

already talked about this in great detail here we have our rough endoplasmic reticulum we talked about

that in great detail and here you're going to have the Golgi apparatus so again it does have this kind of like

convoluted or kind of like coiled membrane if you will and again it's a phospholipid bilayer around that but one

of the big things is on one Edge so the edge facing the rough endoplasmic reticulum is a very specific size so

this is called the CIS Golgi so the CIS Golgi is the part of the Golgi which is near the rough endoplasmic reticulum the

basic concept behind this that we'll talk about a little bit later is that whenever the rough endoplasmic reticulum

is done modifying and synthesizing particular proteins what it'll do is it'll butt off a little vesicle that

contains its particular proteins that have been modified in a particular way to go to the golgiene that goes on the

CIS side of the Golgi and I told you that one of the ways to be able to remember

that it's destined to go to the Golgi is that we put specific types of proteins on its surface that really kind

of says hey buddy it's time for you to specifically go to the Golgi on the side you guys remember what that protein was

called here these are called your Cop 2 proteins and they're really helpful in being able to send this vesicle from the

rafiar to the Golgi so that's one side of the Golgi the CIS Golgi then you have obviously inside of the Golgi the Lumen

that's where some of the reactions are going to take place that we'll talk about in a little bit but on the other

side of the Golgi this side that is going to be facing towards the cell membrane so here's your cell

membrane here this is called the trans Golgi and the trans Golgi I just want you to

think about in two ways one is after all the modifications occur inside of the Golgi to that protein what it does is it

does something really cool where it'll Bud off the modified protein in a particular way where it's then sent to

either go to the cell membrane and from here it can be excreted or become a part of the membrane or it can also do

something else where it turns into we'll give it a different color so we understand it's a different thing it can

get turned into lysosomes so that's the other aspect of the Golgi and again inside it it'll have this

protein that'll undergo a bunch of different types of modifications so that's really kind of when you talk

about the Golgi the basic structure of it is there's this convex let's actually write that down as well the convex side

also known as the CIS Golgi also known as the side of the Golgi facing the rough endoplasmic reticulum or the trans

Golgi this is the concave side this is the con cave side also known as the trans Golgi also known as the Golgi that

faces the cell membrane or those lysosomes that it's nearby all right so before we move on and start talking

about the function of the Golgi apparatus I want you guys to watch a quick little animated video by our

friends nucleus medical media they got a really awesome video that will give you a quick little recap but in a cool

animated way check that out and then we'll talk about the function of the Golgi apparatus in more detail proteins

and other materials emerge from the endoplasmic reticulum in small vesicles [Music]

where the Golgi apparatus sometimes called the Golgi body receives them as proteins move through the Golgi body

they're customized into forms that the cell can use the Golgi body does this by folding the

proteins into usable shapes or adding other materials onto them such as lipids

or carbohydrates [Music] you will see an organelle called a

lysosome lysosomes are the garbage collectors that take in damaged or worn out cell

parts they are filled with enzymes that break down this cellular debris so we're back

now so one of the big things that I want you guys to understand is Golgi apparatus with the function of it it's a

really cool structure and we have a little bit of an idea here that it has three particular types of functions one

of the biggest functions is it modifies proteins right so it seems those vesicles we already kind of talked about

this a little bit to recap it again because it's always good for repetition inside of the nucleus is your DNA DNA

can get transcribed into something called mRNA mRNA can then leave these vesicles

and then bind onto all these ribosomes that are placed on the rough endoplasmic reticulum and then from here it'll then

do what what we know is it can get translated and when it gets translated it synthesizes some specific molecules

like proteins which are going to draw with these like Globs here these are my proteins now what happens is the

proteins go through a particular process in the rough ER that we already talked about called in-linked glycosylation so

they'll run through the rough ER and then after they run through the rough ER we'll just quickly recap here

what did they have what happened here in the rafiar again well when it's going through the rough ER we said that they

add on a sugar residue and oligosaccharide and they added on to if you guys remember they added on to

asparaging that's why we call it the in-linked glycosylation so if you guys remember just as a quick recap in the

rough endoplasmic reticulum the particular reaction that took place was what's called n linked

glycosylation now some of you might be wondering why do we call it in linked really really

quickly all it is is you take this this blue color here this blue color here this is

a sugar molecule here's your sugar molecule you're going to add it on to a protein but on this protein there's a

specific amino acid and this amino acid here which we're going to kind of show like this is

called asparagine and a spare Gene when it kind of connects or clicks with this sugar

molecule really asparagine has a amino group on it and there's the N that's linked to our sugar residue that's why

we call in-linked glycosylation but protein's been synthesized at the rough ER modified a little bit in the rough ER

via in-link glycosylation and then packaged into a vesicle and then once it's packaged into this vesicle it says

all right baby let's send you on to the next Point here and the next thing I'm going to do is

I'm going to send you over to the gold Gene do you guys remember which part of the Golgi face the rough endoplasmic

reticulum it was the CIS Golgi or the convex side of the Golgi and in it it's got this Protein

that's undergone some small modifications you guys also remember what was the protein on the surface of

the vesicle that determined its transport to the Golgi it was the cop 2.

Cop 2 protein and that will determine its direction of saying hey you need to go to the Golgi and then what it'll do

is it'll fuse with the actual membrane of the Golgi because they're both phospholipids and lipid will dissolve in

lipid we know that so when it fuses here it'll fuse with this Golgi membrane and then release its

contents which is this glycoprotein where right into the Golgi apparatus And Then There She Goes to get further

modified now really quickly before we go on and talk about the Golgi does

there's a reason I mentioned this Cop 2 protein so cop2 protein allows for One Direction this direction from rough ER

to the Golgi well there's probably a cop one protein in there yeah you know it's funny

sometimes if I want certain proteins from the Golgi to go back to the rough ER for whatever reason maybe more

modification processes need to occur whatever it may need to happen sometimes the Golgi will Bud off

particular molecules here it'll butt off little vesicles and these vesicles will then actually contain some specific

protein in them that they want to send back to the rough endoplasmic reticulum so if

I want to send back a protein to the rough endoplasmic reticulum maybe for some particular reason to get modified

further who knows I could actually bug these off and if they go in this particular

fashion where let's say that they move from Golgi to Golgi all the way from the trans side to the CIS side and then from

here it buds off and then tries to move its way backward towards the rough endoplasmic reticulum

where it can then actually do what maybe it fuses and releases its contents back in this is another

particular protein that has to regulate this do you guys know what this protein is that actually is on the outer surface

that determines it going backwards from the trans Golgi to the Cisco due to the rough ER because what that is this

protein on the surface is called cop1 this is called cop1 so what I want you to know is cop1 allows for the transport

of vesicles containing glycoproteins from the trans Golgi to the Cisco Golgi to the rough endoplasmic reticulum cop2

controls the movement of the glycoprotein from the rough ER to the CIS Golgi that's what I want you guys to

understand okay cool next thing is we got the vesicle via

moving anterior grade anterior grade will be cop two retrograde will be cop one

now once this is continuing to move anterior grade towards the the end direction which is cell membrane

lysosomes that's the whole point once it gets into this part here so we're going to release from this vesicle our

glycoprotein once it's released time for it to undergo some specific processes

so there's a couple different things that these enzymes that are present inside the Golgi will do you know what

they'll do they'll do a bunch of different modifications believe it or not so it's

going to run through this like a football player in practice and undergo a bunch of different modifications and

by the time it's completely modified what it's going to have at the end of it now is the fully packaged modified

protein that now has a very specific destination for it so okay now here's my protein and maybe

I've modified it a little bit more here's my protein and then on it let's just say I have here is a little bit of

different I got all these different things that are added onto it what are the reactions that occur here in the

Golgi that are a little bit different let's write these down the first thing is I take this protein

right and let's say here I've already had this process occur I've already had let's say

here I have my in-link glycosylation so this is already occurred in the rough ER

once it goes to the Golgi it can then do three particular things I can

trim a little bit of this I can trim the sugar residues off of this in link glycosylation so that's one thing I can

do so let's write that down first thing I could do is I could trim

the in linked glycosylation and that might just like make the

protein a little bit more specific to be activated so now if I were to have this protein maybe instead

of it actually having all of these things here it's just going to have

a shorter a shorter sugar residue and that might be enough

to activate this particular protein so now all I did was I just trimmed it a little bit and now in this state Maybe

it's active this is an active Protein that's ready to be released or incorporated into the membrane or become

a part of lysosomal enzymes the second thing I could do that's one thing I could do one thing I could do is

I could trim it the second thing I could do is I could add another sugar residue but not to an amine group I could add it

to a hydroxy group the oxygen group and so if I do that we actually call since in linked was I was adding a sugar to

the amine group of an amino acid well o linked glycosylation which only occurs in the Golgi

would be adding a sugar residue onto what onto the hydroxy group here of an amino

acid so you see notice how there's no kind of sugar residue now if I draw this one here look at this puppy here so now

I got this next one here this has gotten a mean group here's I got our nh2 group and maybe it

has again some type of residue here but now off of

this I want to add a sugar residue onto this one so now I have a sugar residue on the hydroxy group of two

particular amino acids you don't have to go crazy but the two amino acids here that it can add

on to and make this one active that you could add on here is one is called serine

is a type of amino acid with that hydroxy group and the other one is called

threonine for the amine group this one here is called we're going to abbreviate asparagine

okay so these are two of the mechanisms so far one is I could trim the sugar on the

Inland glycosylation add a sugar to the hydroxy carbon the O the oxygen carb the oxygen molecule of the protein the

glycoprotein and the third thing I can do which is really important is I could do what's called phosph

orylation so it's the last particular reaction here Foss

forelation and all that happens here is you phosphorylate a particular molecule on

that Sugar residue called mannose so you see how on this there's a sugar residue let's just say

on that one of the sugars I'm gonna put is mannose so maybe on this one there's a little

Mano sugar maybe on this one there's a little Mano sugar same kind of Concepts I'm going to add a

phosphate onto the mannose and when I do that the end result should be

very very important here carboxy group a mean group here you have your nh2 group

here you have hydroxy group let's say that there's a sugar molecule on either one of these it doesn't really

matter sugar molecule here sugar molecule here but the big difference here is that

there is a mano sugar here and a mannose sugar here on that Sugar residue okay if I were to put a phosphate on

these it activates them very very specifically so I put a phosphate group onto this and when I phosphorylate the

mannose of these sugar residues on the glycoprotein it activates it makes it only disestant for one particular point

this is active and it will only be active for lysosomes it'll only these proteins will only go

to become lysosomes super important so this is the protein modification one is I can trim it the sugar on the

in-linked component one is I can add a sugar on the oxygen of serine threatening the third thing is I could

phosphorylate mannose on the sugar residues and make it only particular where these proteins only become a part

of the proteins of lysosomes so now all this is occurring in here what types of things again trim

Ming is one mechanism second is O linked glycosylation

and then the most important one is phosphorylation phosphorylation and this phosphorylation

is specifically for mannose and this will allow for the stimulation of lysozomal

enzymes only that is key okay so now whenever all these modifications occur maybe I add a

little sugar residues on there on different points right or maybe I add a phosphate group somewhere on that man of

sugar all these different things have occurred after it's done it's then said today okay well I've done

what I need to do what I'm going to do is I'm destined for three particular things

one is if I don't have a mannose that's phosphorylated then I have glycoproteins

that have been you know completely activated in a very specific way and they're ready whether it be trimming

whether it be in-link glycosylation o-link glycosylation they're done from here we can do two things with these

one is I could fuse them with the cell membrane second thing is they could fuse with the cell membrane and be excreted

they could be excreted right we've already talked about this a couple times so now this could actually be

excreted out of the cell or it could become what else lysosomes and the only way that we know

that you'll make lysosomal enzymes is you have the glycoprotein undergo a very specific type of reaction it'll have the

inland glycosylation it'll have the oling glycosylation but on that Sugar residue there's one

specific sugar called mannose which I have to phosphorylate and this will become

lysosomes so the destination the Golgi says I know where you need to go I'm going to send you to become a part of

the membrane I'm going to send you to be excreted or I'm going to send you to become lysosomes that's another function

a really cool function of the Golgi apparatus and so from here it can actually determine the three

destinations one is they can say I'm going to package you to go to the lysosomes

so now these vesicles when they butt off this is now a lysosome

or I can send you to become a part of the become a membrane protein so maybe this glycoprotein is going to

be a channel protein maybe it's going to be an ion maybe it's going to be a carrier who knows what the heck it's

going to be or the third thing is it can be excreted via EXO

cytosis so these are the three particular things that can happen from the Golgi so the

Golgi receives proteins glycoproteins modifies them in these three particular ways

and then determines their destination because you know what's really cool is when it modifies it in a particular way

it modifies it to where it gives this thing a specific signal sequence so these have like a specific signal

sequence so it's kind of like a little like a like an Amazon thing like when you go to Amazon they have to package

particular things and determine where they're going to go they put a little tag on these proteins these

glycoproteins that says hey here's where you need to go and then it'll help to guide them towards these particular

locations so if I want this to go to the cell membrane I can actually use specific proteins let's represent this

one with let's do it here with pink why not I can put little proteins on this that coat these and make sure that

they're destined to go towards the cell membrane to either be excreted or to also be again a part of the cell

membrane and these proteins typically tend to be clathrons so clathrin proteins

okay and they'll coat these vesicles and say hey you need to go to the cell membrane to either be released or do

fuse with the cell membrane the last particular mechanism of the Golgi apparatus is it can recycle

proteins so let's say on the cell membrane here I have a particular protein

that it's done its job it's completely finished its life cycle and says hey you're done buddy what I want you to do

is so let's say it's this protein let's say this let's say that the Golgi manufactured this particular protein

right here and it did its job so it helped to be able to modify it determine its destination incorporates into the

cell membrane over time over time the protein becomes old it's time for it

to actually be and we got to kind of fix you up a little bit take you back in what it'll do is it'll invaginate this

puppy and it'll actually bring this in into a little thing called an endosome

and then what will happen is this endosome may get kind of broken down by lysosomes

and whenever it gets broken down what it may do is it may release these proteins back into the Golgi to be further

modified repackaged and sent back out to go back to the cell membrane so that's another

particular function of the Golgi apparatus so again recapping the functions of the Golgi

first thing is it's involved in protein modification receives proteins from who the rough ER going to which side the CIS

Golgi how does it know to go there cop two if there's proteins that are determining it to go back to the rough

ER for maybe further modifications how does it need to go back there from trans to CIS to rough ER cop one is a protein

on the vesicle that determines its destination if it goes to the Golgi protein gets

released into the Golgi the Golgi modifies it by which ways Cuts some of the sugar off of the end

linked point of the amino acid asparagine or add some sugar residues on the hydroxyl or the oxygen group of an

amino acid or what else does it do it maybe takes the sugar residues that you have here

and finds one specific sugar mannose and adds a phosphate group onto it phosphorylation reactions

once it does that that's the three ways that we will activate the proteins and then determine their destination once

we've done this we can then say okay I can send these to become lysosomes membrane proteins are being excreted if

I coat them with clathrons they're usually destined for the membrane or to be excreted if it has this mano6

phosphate on it it's destined to be a lysosome and the last thing is for proteins that

are maybe worn down and need to undergo recycling we need to fix them up a little bit we can bring them in and the

endocytosis this process here going from here to here is a endocytosis and we'll make this thing called a endosome

and endosomes technically they get broken down a little bit by something called a lysosome which you already knew

breaks down some of the proteins a little bit and some of the proteins may actually get

taken back up by the Golgi and get recycled and then if they get recycled we can kind of do some modifications to

them repackage them and send them back out so that's a cool concept all right my friends this video now

covers the Golgi apparatus all the structure and the functional components I hope it made sense I hope that you

guys liked it as always until next time foreign [Music]