Cell Biology | Cell Structure & Function

All right ninja nerds in this video today we are going to be talking about the structure and function of the cell also if you guys haven't already go watch our video where we talk about how i study and prepare for videos within that i kind of gave you guys a sneak peek of how i pretty much went through studied this topic developed notes diagrams and then drew it all on the board now we're going to go through it Before we get into this video though please continue to support us by hitting that like button commenting

down in the comment section and please subscribe all right ninja nerds let's get into it all right an engineer so we're going to take a tour through this cell talking about what all the structures of the cell are and then what they do so the first thing we got to talk about is the brain of the cell the pretty much the center of the cell where everything That a cell is kind of really begins in all centers around and that is the nucleus this is the big mama the nucleus now what we have to talk

about with the nucleus is a couple different components of the nucleus what are the different components of the nucleus well the first part of the nucleus is as you can see you see this kind of like blue membrane that's double layered here So you have an outer layer and then you have a inner layer on this side right so this is our inner layer these two components make up what's called the nuclear envelope so you have an outer layer and then you have an inner layer i know that sounds pretty obvious but there's a different

there's different functions for the outer and the inner layers So the outer layer let's actually first say the nuclear envelope you have two layers the outer layer and the inner layer what is the purpose of these layers so the first thing that you need to remember is that the outer layer is where you have lots of ribosomes so ribosomes are actually going to be kind of found outside on that outer layer the reason Why is in the actual nucleus you make you take dna and convert it into a structure called mrna and mrna has to

move out via the nuclear pores and bind onto ribosomes on these outer membranes which then get moved to the rough er we'll talk about that a little bit later but that's the big thing i want you to remember about the outer membrane the inner membrane has a very very important protein structure that binds to the the dna and Histone proteins and controls a lot of cell division it's this green protein here that green protein that lines the inner membrane is called lamins and lamins are very very important structures that control the structure of the nuclear

envelope they're also important for cell division and interacting a lot with the chromatin there's actually a disorder whenever there's a mutation in this lamins it causes progerias so it's important that We kind of know these two components of the nuclear envelope the next thing is in the nuclear envelope you see these red proteins that are dispersed throughout it those red proteins that are dispersed throughout it these are called nuclear pores so what are these called nuclear pores and the whole purpose is it's honestly pretty straightforward right if we want to move things in ions or

proteins or nucleotides or different Things in and out of the nucleus that's the function of the nuclear pores and there is things we'll talk about this a little bit later in a more specific video where we go more in detail on the nucleus but there's special types of transporters that are associated with those nuclear pores we'll talk about those in other videos but again another important thing that's a part of the nuclear envelope if you Will that actually kind of uh kind of separates different portions where there's little pores is called these nuclear pores and

again the whole purpose of this is to allow for transport and what kind of transport transport between the cytoplasm to the nucleus or nucleus to the cytoplasm that's all it is pretty straightforward the next one is this red diced up structure here called the nucleolus The nucleolus is very very important and the reason why is this is the site of a particular type of rna synthesis you know there is a particular type of rna what we call rrna so we're going to denote this as r rna synthesis this occurs in what structure this occurs within

the nucleolus now the reason why that's important is when you take rrna you synthesize it within the nucleolus and you combine This with proteins so then combine with other types of small proteins guess what you make you make ribosomes so really what we can say is is that the nucleolus which is a component in the nucleus is important for making ribosomes which is made up of rrna and small proteins the last part of the nucleus is all of these blue structures you see all these blue structures that are kind of Dispersed throughout i kind of

made circles around them this is called chromatin this is called chromatin and chromatin is very very important because this is what really makes up who we are as kind of humans and it's very important for us to know the different components of chromatin so within the nucleus you have this structure called chromatin so what in The heck is chromatin chromatin is made up of two primary things dna and proteins but the main protein is histone proteins histones these two things make up our actual genetic material and this chromatin can actually come in two forms two

important forms one is called euchromatin and euchromatine is the loose chromatin And it's the one that's going to be more for expression of the dna to transcribe the dna and make different types of mrna or undergo replication so euchromatin should be more in the center of the actual nucleus and the next one here is going to be hetero the heterochromatin and the heterochromatin is going to be the tight chromatin this is going to be the chromatin that you're actually going to See closer towards the inner membrane of that nuclear envelope so we're understanding this right

so we know the different structures and the different components here of the nucleus the last thing that i want us to understand here is what in the heck does the nucleus do we're going to go into way more detail in this in future videos but what you need to remember is that chromatin which is made up of dna we can Take dna and do a bunch of things with it what can we do with it we can take dna and we can make more dna what is this called dna replication i can take dna and

make rna and that is called transcription and then also you need to know that there's different types of rna what are the different types of rna there is t Rna there is mrna and r rna so it's important for us to understand this kind of things that are happening with inside the nucleus which is what you have dna replication and transcription and particularly making of rna molecules and these are the rna molecules and again we'll go over these In more detail in future videos but this tells us what the function of the nucleus is and

what the components of it are let's move on to the next organelles okay so the next thing that you guys need to know here is this next filamentous membranous structure that is located within the cell this beautiful organelle is called the rough endoplasmic reticulum so it's called the rough endoplasmic reticulum we're going to put E r so the rough er that's commonly how we refer to it as right so the rough endoplasmic reticulum or the rough er now the rough er if you notice it's this filamentous kind of network here but there's another structure here

called the smooth endoplasmic reticulum so you have the rough endoplasmic reticulum and then you have the smooth the smooth endoplasmic reticulum the smooth endoplasmic reticulum and rough endoplasmic reticulum differ in What way this is very simple you see these little red dots that are located on the rough endoplasmic reticulum it's called ribosomes so within the rough er this contains ribosomes on that outer kind of membrane structure on the smooth er there is no ribosomes that's really it there's nothing much more that you have to know about kind of The structure of the rough er and

the structure of the smoothie are you know that it's an organelle and the big difference between these structure wise is roughy iris ribosomes smooth the r does not have ribosomes so now the next thing has to come down to what are the differences in function here that's really where it kind of lays in right so the first thing we have to do is before we move into what it does we have To kind of pick up a quick point here from the nucleus and move to the rough er so you know we said within the

nucleus you have dna and from dna you can undergo transcription what is that called whenever you go from dna to rna whenever i go from dna and i make a molecule called mrna and that mrna then binds with a ribosome Here's our ribosome a little like red dot there that ribosome will then do what it'll undergo the process of translation taking the rna and making proteins well what happens is that ribosome it's going to start synthesizing and making proteins from the mrna so now i'm going to have this protein that gets pushed in here from

the ribosome now that's important because the rough Er is obviously going to be a site of protein synthesis then that's one thing we can say it could be a site of protein synthesis because that's where the ribosomes are kind of sitting on so that's one function of the rough er so one function of the rough er we can say is is it's a site of protein synthesis site of protein synthesis And we're going to talk a little bit because there's different types of proteins that we make proteins that can be within the cytosol proteins that

can be within different organelles proteins that we can secrete proteins that we can put into the membrane generally the proteins that the rough er is making is going to be proteins that will become lysosomes so proteins that will be incorporated Into our lysosomes proteins that will go and get incorporated into the different organelles like the membranes of organelles or the cell membrane or proteins that will be excreted so that is really the big thing that i want you to remember about the rough er site of protein synthesis but particularly for these types of proteins the

next thing is what else does it do with the proteins we know what Synthesizes them but you know what else proteins have to fold a particular way for it to be particularly functional so it also helps with the folding process so it plays around what's called protein folding that's very important so plays around protein folding and the next thing is not only does it help with folding the protein in a particular way it also has little enzymes located kind Of in this actual endoplasmic reticulum that can add on little residues little sugar residues onto this

protein making it active what is this called it's called glycosylation so it can perform what's called glycosylation like cosylation and there's a particular type we'll go into this more in more detail but for the most part it is called in type Glycosylation and all that means is if i were to take a protein here i took it the mrna took it to the ribosome ribosome bound to the rough er it made the protein push the protein in the filamentous network of the rough er it started folding and then once we have that protein here that's

folded properly i'm going to just add on a little sugar residue so this is going to be a little sugar residue and this is going to be my Protein and this is important because this is the way that we activate these proteins so that is the function of the rough endoplasmic reticulum now the next thing one last thing for this is remember i told you that the site of protein synthesis for these particular things so in order for after the rough er has kind of gone through this process of synthesizing it folding it and then

Glycosylating it it then has to package it so then what happens is it'll package off so what happens let's say here's the protein the protein will actually bud into this little portion of the actual rough endoplasmic reticulum and when it does that that'll actually butt off and then i have a vesicle and within that vesicle is going to be my protein What protein will become a lysosomal protein and membrane protein are excreted protein but in order for that to happen i have to move this towards the next organelle which will be the golgi apparatus we'll

get to that one in a second but here's going to be that protein that was coming from the rough endoplasmic reticulum and moving towards the golgi so now we know all the functions of the rough er Now we've got to go over the functions of the smoothie are the smooth endoplasmic reticulum this is a very interesting structure so there's a lot of different types of enzymes located within this smooth endoplasmic reticulum particularly enzymes that are associated with lipid synthesis that's big thing i want you to take away from this so it's primarily associated with what

lipid synthesis there's going to be a bunch of Different enzymes located within these organelles within this organelle and what kind of lipids are we synthesizing fatty acids fatty acids are a big one phospholipids are a big one what else you know there's another really important cholesterol molecule with cholesterol so i kind of give it away so cholesterol and cholesterol is important because this can become hormones steroid hormones testosterone Progesterone estrogen all that good stuff so this is the big thing i want you to remember is this is the site of lipid synthesis so we take

precursor molecules that we get from the cell let's say here's a precursor molecule that precursor molecule for the fatty acids phospholipids cholesterol it will get taken up into this smooth endoplasmic reticulum the enzymes in it will start Using these precursors to pop out little cholesterol or lipid molecules so now from this we're going to have the smoothie r take the precursor molecules perform the lipid synthesis process with the enzymes and then butt off a particular vesicle which is going to contain what fatty acids phospholipids and cholesterol and then guess where we Could send this we

could all send it again to the golgi or maybe even send it to the cell membrane and then from the cell membrane we may release out cholesterol maybe release out fatty acids pretty cool right there's another set of enzymes that are important here the next set of enzymes is called cyp450 you're like what the heck is that cyp450 enzymes are very very important for Detoxification so you know whenever your liver your liver has a very high concentration of these enzymes because that's our detox center right so if you go to your liver there is lots

of this enzyme and the reason why is any drugs any toxins any alcohol you know alcohol ethanol etoh any of these things have to go to the Liver and what your liver does is is it undergoes a process called biotransformation or xenobiotic metabolism and it breaks down these substances and it's because of these enzymes located within the smooth endoplasmic reticulum so it undergoes what's called bio transformation ba-boom That is important the next thing here this is an interesting one you know within our cells we have glycogen right you know glycogen it's basically a a big

polymer of glucose and whenever our body needs energy that glycogen can get broken down into glucose but there's a particular step whenever you're breaking down glycogen into glucose there's an intermediate between This called glucose 6 phosphate well in order for glucose 6-phosphate to get converted into glucose guess what it needs there's a particular enzyme on the smooth endoplasmic reticulum and that enzyme will need to take the glucose in give a little transporter that'll take the glucose 6-phosphate in and then a particular enzyme that'll rip off that phosphate on the six carbon of glucose And make

off glucose 6 phosphate and make glucose so the important thing to remember here is that this actual smooth endoplasmic reticulum is also important for glucose 6-phosphate metabolism so it's also important for glucose 6-phosphate metabolism baboon roasted last one Last function you know this is a smooth endoplasmic reticulum it's in in a lot of different organs but you know organs that contain lots and lots and lots of calcium like in our muscles there's kind of a an analogous structure there called the sarcoplasmic reticulum these can store lots of calcium and you know there's little pumps that

are located on the smooth endoplasmic reticulum and Whenever we need calcium whether it be for different types of transport processes or for muscle contraction guess what we can pump that calcium out into the cytosol and utilize it for all these different types of chemical processes so what is the last function here for the smooth endoplasmic reticulum it also stores calcium ba-boom all right we've covered the functions of The rough er and the smoothie are let's now move on to the golgi apparatus all right ninja nurse so what have we established up to this point so

we know that we've understood the function of the rough endoplasmic reticulum we understand the function of the smooth endoplasmic reticulum and again to kind of go off of that that smooth er again what did we say it could also make the different phospholipids and cholesterol and different types of Fatty acids and that also from the smooth endoplasmic reticulum can get sent to the golgi now the vesicles that are coming from these two areas primarily the rough endoplasmic reticulum we're going to focus on from this point but again realize that everything from the smooth er as

well all right so what is the name of this next organelle that we have to talk about this is a very very important structure called the golgi apparatus Right so we're going to call the golgi now the golgi apparatus is a very important kind of like packaging organelle if you will so it takes these vesicles coming from the rough er from the smoothie are and when it takes it into the golgi there's an anatomical term here on this side of the golgi where these vesicles from the rough yarn smoothie are going to this part of

the golgi here is called the cis Golgi okay or they call the cis face of the golgi but we're going to call it cis golgi then what happens is through these systematic steps these proteins and different types of fatty molecules that get taken to the golgi will go through the golgi and as it goes through the golgi it'll actually bud off right so then you're going to butt off some type of molecule in the golgi Whether that be a protein whether that be lipids cholesterol whatever it buds off and then leaves the golgi this side

where the vesicles are coming out of the gold gene going towards lysosomes or cell membranes or whatever this is called the trans golgi or the trans of the golgi so that's an important kind of anatomical term or structure component of the actual golgi that you need to Know the next thing here is we have to kind of primarily focus on the function so primary function is it's receiving vesicles containing proteins and different types of sugar molecules maybe attached to it as well as different lipids from the rough er and smoothie guard that's the first function

so first function that you need to know here so it's receiving vesicles From the rough er and the smooth er that's the first thing we know it's receiving the vesicles containing proteins or fatty molecules now let's focus on those proteins because that's where it's more important the proteins that are getting taken into the golgi it might have to modify we saw that it was folded and modified a little bit in the rough er but the golgi might have to Modify it even a little bit more and how does it do that so this modification step

is very important and it's again through a couple different reactions remember we have what's called glycosylation reactions that we talked about with the roughy are the golgi can do the same thing it can do what's called a glycosylation but this glycosylation reactions where it adds on sugar residues there's two Types one is the n type and one is o type what's really important to remember is that the golgi is the only one that can do o type glycosylations in other words i'm adding a sugar residue onto the oxygen component of a protein that's all it

really means in type you're adding a sugar residue to the nitrogen component of the protein nothing special the other really important step here Is it also has to phosphorylate specific types of proteins and that is very important there's a disease called eye cell disease and it's actually related to this phosphorylation reaction so that's why we need to know it so it modifies proteins and some lipid molecules through these glycosylation and phosphorylation reactions the next thing is is it packages these molecules Right and then after it packages these molecules into their own little vesicles remember how

we said that these molecules will go through the golgi undergo these modifications get stuck into like a little vesicle butt off and then pop off here it's going to pop off right so now i got my vesicle containing my proteins and my lipids and all these things that have been modified even more Now what happens is these molecules we already talked about where they're going to go they're going to go and become lysosomal proteins they're going to go and become membrane proteins or they're going to go and be excreted out of the cell that is

the destination and the function of the golgi apparatus so now we understand that now that we've done that we have to talk About another little structure here which is our cell membrane it's another component of the cell all right so the next really really important component of the cell is the cell membrane so what we're going to do is we're going to kind of zoom in on a different part here of the cell right which is our cell membrane and there's different components of the cell membrane so if you look here you see like these

little red dots with like Little you know fingers hanging out this is a part of what's called our phospholipid bilayer so when we talk about the cell membrane there's a bunch of different structures that are involved within the cell membrane and they obviously carry out a very important function so what are the different components of the cell membrane the first component here is these little red little thingies what are these little red thingies these Are called this is a part of your phospholipid bilayer so you have two components of it if we kind of zoom

out on this little guy you have these two components this head component of this phospholipid bilayer is actually the phospholipid and what you need to know about this is that this is polar what does that mean polar means it's water soluble so it's the hydrophilic portion it can interact with water Because it has lots of negative charges on it the other component here is the little tail this tail these are fatty acids and fatty acids are really saturated with hydrogen and so because of that they are very non-polar hydrophobic don't like to interact with water

because they have no real negative or slight changes in charge that's the important thing here so we have this on both sides on the inner Cell surface you would have this phospholipid kind of portion pointing inwards on the outer side you would have it pointing outwards and then you have the tails pointing in towards one another the next thing is you see this little green structure which is kind of lodged between these phospholipid this green structure here is called cholesterol Now you're like like what the heck why is cholesterol coming oh and they even add

on here where could that cholesterol come from the smooth er we packaged it sent it to the golgi and then incorporate it into the membrane we're putting things together ninja nerds but the cholesterol is also incorporated in there and the cholesterol is important because it controls like fluidity okay so it controls fluidity all right So again to recap this whole idea of cholesterol with fluidity again it's just important to remember that the amount of cholesterol if you wanted to think about like this the amount of cholesterol in the cell membrane the more of it you

have the less space there's going to be between the phospholipids so there's less fluidity so more cholesterol less fluidity and the less cholesterol you have here the more space there's going To be between the phospholipids and so there's going to be more fluidity so less cholesterol more fluidity so that's an important concept with that the next component of the cell membrane so we have the cholesterol we have the phospholipid bilayer the next big component here is the proteins so the next one that you're going to have here is these little proteins and these proteins here

my pink marker here These proteins there's different types of proteins there's what's called integral proteins and peripheral proteins and what is really really important for these proteins is that they have various different functions they can act as transporters they can act as little enzymes they can act as linker proteins between other cells so they have a lot of different components a lot of different functions to them but again There is integral proteins and peripheral proteins the big thing i want you to take away from this of the cell membrane is that it basically acts as

a barrier i mean i know that sounds super obvious but it is a barrier it's a selectively permeable barrier and only allows for particular types of diffusion that we'll get into later but there is what's called Simple diffusion right there's what's called facilitated diffusion and then there's different types of what's called vesicular transport and all of these types of processes are involving the cell membrane so in other words moving things from outside the cell to inside the cell we have particular types of processes that we'll Have to go into more detail about but again big

thing i want you to take away from the cell membrane is these different components and how it acts as a barrier for particular types of transport processes all right let's move on to the lysosomes all right so the next structure here is going to be our lysosomes our beautiful little lysosomes now these are very very cool kind of Organelles now what lysosomes are important is they're like these little spherical organelles and they contain very interesting little enzymes inside of them and these enzymes are called hydrolytic enzymes and really the simplest way of describing these hydrolytic

enzymes is you have different types you have proteases Which means that they break down proteins you have nucleases which means that they break down nucleic acids you have lipases which means they break down lipids and you have glucosidases which means they break down carbohydrates so all of these hydrolytic enzymes are located within these little organelles so why is that important Any macromolecules that you bring into the cell whether that be from a white blood cell undergoing what's called phagocytosis whether that be you actually undergoing an endocytosis process from uh it's called clathrin-coated mediated endocytosis that

whole process when you're bringing something in you're bringing in particle matter and these lysosomes are responsible for using these enzymes to break down Macromolecules such as proteins nucleic acids lipids and carbohydrates that's all they do so that's important thing to remember from these hydrolytic enzymes is they're going to be responsible for doing what these all break down macromolecules they break down macromolecules their respective macromolecules as we already said okay that's one thing that i really want You to remember the second thing you know when organelles are getting worn down maybe our mitochondria it's just it's

had a rough day maybe the cytoskeleton's starting to get all jacked up maybe our ribosomes have just they've pooped out and they're done when these organelles have reached the end of their kind of let's say functional capacity we don't want to keep them anymore we want to recycle them we want to break out with the old In with the new so what happens is these lysosomes you'll actually take and package let's say that the ribosomes are done they're tired they're pooped out i'm going to form a little vesicle around these ribosomes and then what i'm

going to do is i'm going to send it to the lysosome and what did i say that the ribosomes are made up of proteins and rna so what do you think which enzymes are going to start breaking down this Ribosome if you bring it to this lysosome the proteases and the nucleases and it'll start breaking down the actual organelle what is that called autophagy so another important thing that you have to remember is that this is one thing breaking down macromolecules the second thing is it undergoes auto phagy of organelles ba-boom Last thing let's say

that a cell has actually been severely damaged you've really damaged this cell the point of the cell is at living and surviving anymore is that it's it's not going to happen you know what i'm going to do i'm going to just have these lysosomes bust open and i'm going to have all of these enzymes proteases nucleases lipase Glucosidases guess what they're going to do they're going to break down all the macromolecule components of the cell what is that called that's called autolysis so that's the next thing to remember is autolysis of damaged cells okay so

cells that even if they are damaged and you want to repair them there's no point of even repairing them at that point it's time to just start All over these things will just bust open and release their enzymes and start breaking down the cell this is the functions of the lysosomes they're little angry little buggers aren't they all right next one pretty cool ones these are actually kind of one of my favorite organelles and these are called peroxisomes so peroxisomes these are also spherical kind of like Little organelles and they contain a lot of different

enzymes but by far one of the most interesting enzymes that they contain is there's two of them one is called catalase and the other one is called oxidase they have other enzymes okay they have like other like metabolic enzymes we're going to title them as that because it can be kind of confusing if you get Into more detail than that but these are the big enzymes so the first one i want you to remember is the catalases oxidases and then other metabolic enzymes why am i kind of telling you all of these things well the

catalase in the oxidase is important for free radicals you know whenever a cell normally obtains oxygen that oxygen can get sometimes converted Into what's called a superoxide anion then that superoxide anti can get converted into hydrogen peroxide and then that hydrogen peroxide can get converted into what's called a hydroxyl radical these things right here from here to here all of these molecules are free radicals very dangerous little suckers can bind onto proteins and nucleic acids and cell membrane and just jack the cell up We don't want these things to accumulate the particular one that loves

to accumulate though in these peroxisomes because of what's called fatty acid metabolism is hydrogen peroxide it really likes to accumulate in there so what happens is these peroxisomes have lots of this catalase enzyme and what they do is they take this hydrogen peroxide and use that catalase enzyme To convert this into water and oxygen which is not that's not that dangerous right that's what we want so that's one of the beautiful things be thankful for these suckers these little peroxisomes they're not they're constantly breaking down this hydrogen peroxide which is a potential free radical and

making water and oxygen that's one thing you know it's important For fatty acid metabolism so they contain little enzymes here particularly catalysts you know catalase not only is important for these free radicals but it also can break down fatty acids the first step in fatty acid metabolism so it plays around what's called fatty acid oxidation without going into too much detail there's actually two types alpha and beta and really all this is is there's diff what's that called branch Chain alpha breaks down what's called branch chain fatty acids and then beta breaks down it's called

very long chain fatty acids but either way you're breaking down these fatty acids into what's called acetyl-coa molecules then not only can it break down fatty acids but it can actually break down the fatty acids into acetyl coa and then we can use those acetyl-coa molecules to make Lipids so we can actually make it can make lipids and there's a very particular type of lipid and cholesterol and you know cholesterol is important because this is also important for making different types of hormones steroid hormones and bile acids but this is the one i want to

focus on for a second The lipid that it makes is very important within the white matter of the brain called plasmalogin and this plasmalogin is a very particular type of lipid that is important for the white matter so it's an important component of the myelin within the white matter so you can have an idea that if there's an issue with The peroxisomes and they can't actually synthesize plasmalogen what happens to the white matter there may be a decrease in white matter production and that may lead to some injuries to the actual nervous system the last

thing i want you to remember is that there's also a teensy bit of alcohol metabolism so it also can break down ethanol there's a tiny little enzyme That catalase enzyme again coming into play not only with the fatty acids but also with the ethanol metabolism it can also break down ethanol so these are some of the functions of the peroxisomes very very important type of little organelle now that we've covered that one let's go into the mitochondria all right ninja so the next organelle that we're going to talk about here is our mitochondria now the

mitochondria is a very cool Enzyme i'm sorry a very cool organelle and this thing is commonly just broken down into like the simplest way of explaining it everybody always knows this it's the powerhouse of the cell it's the the site of atp synthesis yes that is true but we're going to explain about how it actually does that atp synthesis but before we do that again let's kind of highlight some of the components of this mitochondria If you look at the mitochondria of an outer membrane so this is the outer membrane and it's important to remember

that the outer membrane is a smooth membrane and also it has a very high permeability there's a lot of transport proteins on the outer membrane if you look here you have this little folded membrane here on the inside that is called the Inner membrane and usually on most cells we call this inner membrane the folding chris stay we call it the chris day of the inner membrane now this inner membrane has less permeability it's less permeable to the transport of different types of molecules going in and out of it okay so that's the basics inside

of the mitochondria you have this Structure in here called the mitochondrial matrix and this is where a lot of the metabolic reactions are occurring and it's also where the mitochondrial dna is found all right so we have an idea of the structure of the mitochondria the next thing is the function so it's obviously the site of atp synthesis but if we were to just take it just a Little step further when we make atp we make it in two primary ways one is called oxidative phosphorylation the other one is called substrate phosphorylation the mitochondria has

little proteins on its inner membrane that are very important and then a component of what's called the electron transport chain so atp synthesis on the mitochondria in the mitochondria occurs via the electron Transport chain and this type of atp synthesis is called oxidative phosphorylation okay and that's carried out by this electron transport chain the other thing that's important with the mitochondria is that there's a lot of metabolic reactions that occur here a lot of metabolic reactions What are some of these metabolic reactions that occur within the mitochondria well some of them as we know the

krebs cycle that's an easy one right so the krebs cycle occurs here where you have a lot of different intermediates that are involved whenever acetyl-coa gets converted into the entire complete structure right where you have the acetyl-coa and then the isocitrate Citrate alpha-ketoglutarate all that stuff there that's a part of this metabolic reaction the other one is you have heme synthesis so you're making the heme component of different types of uh chrome different types of pigment molecules that are part of the electron transport chain as well as synthesis of heme for hemoglobin or myoglobin The

other one is the urea cycle occurs here so the urea cycle is another big one where you're taking different types of molecules like ammonia and turning it into urea the other one is called gluconeogenesis where you're taking things like amino acids and glycerol and odd chain fatty acids and converting it into glucose a new glucose molecule and the last thing that can occur here Is what's called ketogenesis where you're making ketone bodies from acetyl coa so these are some of the metabolic pathways that occur within the mitochondria one other thing to remember is i already

told you about this but in the mitochondria it has its own little dna so we'll put this up here this is called mitochondrial dna And this actually comes from the mother okay so this is actually going to be dna that comes from the mother and this dna can actually make tiny little proteins that can be involved in some of these metabolic reactions on its own all right so the next structure here is going to be our ribosomes this is the next organelle now ribosomes we have already kind of alluded to these already so we're going

to have a pretty quick run through these but obviously we know that These ribosomes let's kind of talk a little bit about their structure there's two components of the ribosome so you have this large ribosomal subunit so this is the large subunit and usually they always like to say this in eukaryotic cells this is your 60s ribosomes s means vedburg unit but again large subunit and then the other one is called your small Ribosomal subunit and in eukaryotic cells this is a 40s or 40s vedburg unit of the ribosome again kind of a very non-essential

thing to remember but again big thing to remember is that there's two units a small subunit and a large subunit the next thing that we have to remember ribosomes are made up of what two things we already talked about this rrna And proteins so that's the next thing the next thing is that ribosomes can be found in two places we already know one it could be found on the rough endoplasmic reticulum whenever ribosomes are bound to the rough endoplasmic reticulum we call these i know it's super obvious but it's called membrane bound ribosomes okay so

membrane-bound Ribosomes but if these are just kind of in the cytosol freely circulating then they are called cytosolic ribosomes or free ribosomes the reason why we should understand the difference between these two is that if you guys remember the ribosomes that were on the actual rough endoplasmic reticulum what happened what do ribosomes do i guess that's the big question to ask let's actually write that down first what do Ribosomes do they take mrna and another structure called trna and make proteins so they're basically a site of protein synthesis right and we also give this a

particular name called translation so whenever you're taking things like mrna and making proteins Well what happens is if you have ribosomes that are bound to the rough er what are those proteins going to become remember what we said those will become proteins that'll be a part of lysosomes those would be proteins that'll become a part of the membrane like integral or peripheral proteins or they'll be proteins that we're going to excrete out of the cell cytosolic ribosomes those are just going to be making little enzymes Different types of proteins inside the cell that will not

leave the cell so that is important so these are going to be making cytosolic proteins and i know that sounds obviously kind of pretty pretty straightforward but again it's something worth mentioning these are making cytosolic proteins like different types of enzymes that are involved in a lot of your metabolic pathways that occur in the cytosol okay so that's important so that gives us the Importance of ribosomes what they uh what their structure is and what they do now let's finish off with the cytoskeleton all right ninja so now we got to talk about the cytoskeleton

now obviously when we talk about the cytoskeleton the cytoskeleton we're only showing in this kind of one point here but if you really were to show the way the cytoskeleton looks it would it would make this board look disastrous because there would just be lines and fibers all Over the entire cell and that's an important thing to remember that even though we're showing this in kind of like a static zoomed in view of these cytoskeletal elements remember they are scattered all around the cell that's an important thing to remember okay when we talk about the

cytoskeleton there are three different structures of the cytoskeleton The first one that i want us to talk about is called your micro filaments your microfilaments and sometimes to be honest with you we just refer to this as actin okay and i know you guys have heard of actin if you guys have watched our videos before you've heard this term actin it's one of the proteins that are commonly used in muscle contraction right so that's an important thing to remember But when you look at actin there's these little monomers of actin and they all come together

and make this long polymer of actin and you get multiple strands of it big thing i want you to remember with this actin structure first thing when we talk about function you know when you have a muscle cell there's another protein that actin binds with to cause contraction and relaxation what is that protein Myosin so whenever you have actin and myosin particularly in a contractile type of cell what can this do this can lead to muscle contraction and relaxation so this is going to be a protein that can be involved in muscle contraction that is

a very important thing to remember so one thing i want you to remember with the microfilaments are actin is that if it's associated with myosin it can be Involved in contraction the second thing you know in a cell if we were to have like a for example there's a process called cytokinesis when a cell is undergoing mitosis you if you imagine here let's say that here i had to a cell that was going to become two cells so here we had one cell that's becoming two cells right around the central portion here You form this

little constriction ring right this little constriction ring around this point here these actin filaments form that constriction ring and eventually squeeze it to the point where guess what happens you butt off from one cell to daughter cells so it's important for the cytokinesis part of mitosis so cytokinesis of mitosis So it forms a little constriction ring around that which helps to split the cells apart the other thing it's important for you know white blood cells if you take a white blood cell let's imagine here i have a white blood cell and i want to move

a white blood cell from the blood i mean from the blood and have it leave and go out into the tissues well here's A vessel and you know the vessels lined with what's called endothelial cells right well what happens is that this actual white blood cell wants to be able to squeeze through those actual capillaries what is that called diabetes in order for it to do that it needs to be able to change the shape of the cell what do we say cytoskeletal elements do they help to control cell Shape structure all that good stuff

so what happens is the actins polymerize in such a way that it allows for this cell to kind of create a particular shape so all the actin molecules will come at this point and create like this little shape where the white blood cell can squeeze out of the cell so what is that called diapedesis diapedesis Of white blood cells and let's take this one more step let's say you have a white blood cell okay and here's a little pathogen out here here's a little pathogen and i want to take this pathogen in in order for

me to do that i need to create these little like things called pseudopods and what happens is i create these like little arms or Little extensions that come out here to surround that pathogen the actin molecules need to come in and help to create these little arms that'll basically wrap around the pathogen and bring it in what is that called phagocytosis so it's also involved in phagocytosis of white blood cells babushka we did it all right next one The next one is the intermediate filaments the inter mediate filaments the intermediate filaments are a very interesting

type of structure and one of the things that we need to know about these intermediate filaments is that they are primarily very tough high tensile not very much movement they don't give they don't have a lot of give to them So why that is important is let's say that we take here a cell here is a another cell okay we have two cells and then you know around the cell there's a lot of protein network out here what is this called all this protein network that sits outside of the cell this is called your extracellular

matrix it's made up of collagen and elastin and a bunch of different types of proteins we know that right Well what happens is we take this protein here let's actually draw it in another color here let's use this blue here this protein here let's say here we have one end of it it can connect to from the cell can connect the cell to the extracellular matrix that's one thing it can do so it can help to hold the cell and anchor it to the extracellular Matrix the other thing here is maybe i have another protein

here another protein here in these cells these can connect cell to cell so they help to anchor and hold the cells to each other and then let's add another thing in here you know these little organelles remember i told you that if you imagine The cytoskeleton they're all over this cell imagine here i draw an organelle a mitochondria or you know the nucleus whatever here's our nucleus right these cytoskeletal elements are also going to be bound to these organelles so it helps to anchor the actual cell to The extracellular mantra matrix anchor cell to cell

and anchor the organelles inside of the cell so they're not just kind of like [ __ ] floating around everywhere right so that is the function of the intermediate filaments so three functions is an anchor if you will and it anchors what things one is cell to cell Two is cell to the extracellular matrix and three is sell to different organelles we done did it okay so the last component here the last part is this microtubules these are very very cool cytoskeletal elements okay and what i really want you to remember about microtubules okay is

they're made up of two different Types of protein units so i drew these in different colors a pink protein maybe that represents what's called alpha tubulin and pretty straightforward right and then with my blue marker here another little dot here is called beta tubulin these things come together and form these little filaments and then like 13 filaments come together and eventually form this entire Microtubular structure why this is important is very very interesting so microtubules one of the really big function here is that it provides what's called intra cellular transport okay now it's a it

seems odd but on these microtubules you have these little proteins imagine here you have like a little protein here okay And these proteins there's two different types of them there's what's called dynein and another one which is called kinesin and these are called motor proteins and what these motor proteins can do is they can bind on to organelles they can bind on to different vesicles which maybe have proteins or lipids or things that you're moving towards the cell membrane are bringing in to the cell These are transporting them throughout the cell to different places that

they need to go to that is very important so again it's acting as the the railway right or the railroad system by which you're transporting different substances by having to use these motor proteins big thing to take away from this this isn't there's no free lunch on this this requires Atp to drive this process this is an atp dependent process for this intracellular motor protein transport the second thing that's important for is cell division you know whenever a cell is going through the mitosis phase there is this phase where you have the chromosomes like this

right and they're all lined up Okay and metaphase well at that point here the centromere there's little proteins on the side called the kinetochore what happens is these microtubules they click in to that kinetochore and what happens is as they start to break down they depolymerize it separates these chromosomes into the two separate sister chromatids so again big thing microtubules connect to the Kinetochore where the centromere is the center part of the chromosome and separate them into sister chromatids so that's the other important thing is cell division particularly separating separates the chromatids okay the third

thing here is it is important for cellular extensions cell extensions And what i mean by these extensions is there's two big structures they form the base of these structures and you form what's called the cilia which is a very important structure and you form what's called flagella these are structures that again you have motor proteins like dyneins and things like that that are incorporated into this these uh cellular extensions but what happens is These cilia and flagella they create a beating like motion or twisting like motion and what that helps for is that if you

have these motor proteins which are constantly utilizing atp to beat and create this movement here cilia is good in our respiratory tract because it helps to clear out mucus it's also in the fallopian tubes you know when you have to move the o or the oocyte or the ovum in this case if it's fertilized you Have to move it towards the uterus we need those things and microtubules make up the base of that cilia flagella in order for the sperm to be able to move towards the oocyte or the in this case the secondary oocyte

it needs to have that type of motion and again microtubules make up the base of the flagella and utilize these dynein proteins to create that whipping motion so now we have an idea what these microtubules do hi ninja so in this Video we covered the structure and function of the cell it was a long one but i hope it made sense and i truly hope that you guys enjoyed it and i hope you guys learned a lot if you guys follow through this entire process of how i study prepare draw and then go through the

lecture i hope that you guys were able to come up with a similar process and i hope it helped all right nigerians as always we thank you love you and until next time [Music] you