Understanding Mitochondria: Structure, Function, and Importance

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

the structure and function of the mitochondria before we get started if you guys like this video makes sense

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below take you to our website where you guys can check those out all right mitochondria it's always referred to as

the PowerHouse of the cell right we're going to dig a little bit deeper okay so when we talk about the mitochondria

let's first go through the structural components of it and then what we'll do is we'll dig into the function of it

step by step kind of not just sticking with the only factors that it produces ATP there are a

lot of things that this son of a gun can do all right so the mitochondria first thing is it's really kind of I'm not

even kidding this is the way that they hold in the textbook a sausage shaped uh kind of like organelle inside of the

cell and when we look at it and actually zoom in on the structure there's a couple different components that we have

to know the first one is that you have this kind of like membrane and it's double layered it has like a outer

membrane out here so this is called your outer membrane and again it's made up of a like a phospholipid layer bilayer

actually Auto outer membrane big thing that I kind of want you to take away from the outer membrane

is the outer membrane is a very permeable membrane okay so it's a very very permeable membrane highly highly

permeable so it's got these big pouring molecules that allow for things to move in and out of the mitochondria one big

thing that you may see on your exam all right so here's the outer membrane then if you look here's the other

component of it right here you see how we have the outer membrane which is this kind of maroon line and then here we

have another Moon line that's called the inner membrane this is called the inner

membrane again another phospholipid bilayer which is pretty cool big thing to take away from this one though is it

is not very permeable has a lot of selective proteins Transporters that are present on it that really are very

closely regulated and determine what moves in and out of the mitochondria so this one is less permeable really kind

of a big just term that I want you guys to take away from these two now there's a space

and that exists right between these two so here was the outer here was the enter there's a little space between these two

and this little space here is called the inter membrane

space really really cool thing about this one and we'll talk about it later is that it

is really really highly concentrated with proton ions which is really really helpful with your electron transport

chain so we'll get into that a little bit later all right so we got outer membrane inner

membrane inter membrane space which is kind of just a little bit of fluid rich in protons okay

we come into the inner part here so one more thing you see how they have the inner membrane if we were to follow this

thing along look how it kind of continues continues and then you get like these like little invaginations

that are coming off of the inner membrane that's a really really important thing so what I want to add on

here is with the inner membrane so with the inner membrane so with the inner membrane we're going

to rewrite it there is a specific type so this kind of invagination is actually called the Christa so it's a

continuation of the inner membrane but invaginates into the center it's all these things here's a Chris Day here's a

Christa here's a Chris Day Chris Day Chris Day Chris day okay the whole purpose of these puppies is to increase

the surface area for a lot of specific types of metabolic reactions that we'll talk about a little bit later okay

so we got outer membrane inner membrane intermembrane space the inner membrane there's a special type of them which

invaginates into the actual center of the mitochondria called the Christa which increases the surface area for a

lot of metabolic reactions the last part is all of this kind of white space here which is basically the

mitochondrial Matrix so really all of this in here is called your mitochondrial Matrix and it has a bunch

of different fluid and solutes in it but two particular things that are really pertinent to The Matrix

um the major the mitochondrial Matrix is what's called mitochondrial DNA which is represented right here see these little

guys right there that's your mitochondrial DNA it's really cool because this is actually maternal DNA so

it's maternal DNA and then the next part here is not only is their maternal DNA which

obviously has some types of genes to uncode to make particular RNA to make proteins but we need certain things that

are helpful in making proteins so mitochondrial DNA can make RNA but we need ribosomes

to be able to translate that RNA and make proteins and some of these proteins the mitochondria can make

on its own to help with its own functions so that's a really really cool thing and we'll get into that a little

bit later but this is the big big thing that I want you to understand so again to recap it this is outer membrane this

is inner membrane a special invagination of the inner membrane into the center is called the crestae which one's highly

permeable outer which one's less permeable inner what's the space between the outer and the inner membrane the

inner membrane space what is it rich in proton ions and then what is all of this fluid here that is in the center of the

mitochondria the mitochondrial Matrix rich in mitochondrial DNA and ribosomes the mitochondrion is an organelle that

is the PowerHouse for both animal and plant cells during a process called cellular

respiration the mitochondria make ATP molecules that provide the energy for all of the cell's activities

cells that need more energy have more mitochondria let's now dig into the function of the

mitochondria specifically what I want to talk about is the membranes so we'll get into the Matrix that's next but what I

want to talk about first is let's talk a little bit about the outer and the inner membrane and what are some of the

functions that this puppy does so let's come down here the first thing that I want to discuss here is it plays

a huge role in protein transport the membranes so what we're doing is we're zooming in this is a cell

sorry so this is a cell here this here is the nucleus so this is our nucleus

here is a ribosome these are free ribosomes and then I'm just zooming in on the

mitochondria so I'm going to represent this as the outer membrane the inter membrane space and the inner membrane

and then what would this be this would be the Matrix so I'm just zooming in onto the part of the

mitochondria now the mitochondria has DNA right it has

DNA here's like some of that mitochondrial DNA and it can make RNA which can helpful to make some proteins

but it doesn't make all the proteins that it needs to be able to function and so sometimes we have to take some of the

proteins from the nucleus so the nucleus will help us to make RNA RNA will then make proteins

and these proteins have to get sent into the mitochondria and that's really really important

so for example here here's our DNA it's going to make mRNA m r and a that mRNA will then come out

via the nuclear pores when it comes out via the nuclear pores here's my mRNA it'll then combine with

ribosomes and from this from the ribosomes will then synthesize what proteins but here's the big thing these

proteins are unfolded oh there we go it's unfolded therefore it's not Super Active it's not the

active form okay so the mitochondria has special Transporters that really are special in

moving these unfolded proteins that it needs to be able to perform reactions inside of this the mitochondria it needs

to transport it across so what happens is this protein here will get chaperoned and then we'll bind

onto this like little receptor here and there is this outer membrane translocase we literally call them Toms translocase

of the outer membrane and what happens is once this unfolded protein binds to the receptor what it'll

do is it'll open up this Tom and move this unfolded protein into the inter membrane space

and the inter membrane space a little chaperone protein will bind to it and bring it to this next point so it'll

bring it to this next receptor on the inner membrane when it binds here it activates this particular stimulated

this receptor stimulated this receptor when it stimulates this receptor it opens up this next channel on the inner

membrane this is called Tim I'm not even kidding so translocase of the inner membrane and when that binds onto the

receptor it opens up and pushes the unfolded protein into the mitochondrial Matrix in the

mitochondrial Matrix we need maybe this protein to perform specific things maybe it's an enzyme that plays a role in a

lot of metabolic reactions and I need him and so what happens is you have specific

types of proteases or other enzymes that will then work on this protein and properly fold him

together and activate him and make him into a specific special enzyme and now this is a active

folded enzyme and it's ready for it to perform its functions inside of the mitochondria

and there's so many different proteins that you need and so it's a really really important point because the

mitochondrial DNA right the mitochondrial DNA it only makes like 15 of the proteins so really when it goes

to make proteins these proteins that it makes is only 15 of what's needed so that means I need a lot of proteins from

the nucleus to help me to perform a lot of the functions so that's one of the cool things the mitochondria accepts

proteins and they're unfolded form brings them into them and then activates them by folding them properly and then

uses those for their metabolic reactions pretty cool right all right that's one of the functions of

the membrane let's go on to another one which is a plays a role in like miscellaneous transport and then we'll

talk about the Big Mac Daddy function of the mitochondria that the membrane plays a role in and that is the electron

transport chain all right my friend so now next one is it also plays a role so with protein transport is a big one but

it plays our own like small miscellaneous things and this may seem like very like straightforward and I I

kind of thought that was common sense it is but it's just a quick reminder of things that also a lot of things move

across the mitochondrial membrane right and what are those things well I want you to understand and we're going to get

into them a little bit but metabolic reactions they're very very heavily involved in the the mitochondria and so

in order for some of these metabolic reactions to occur I have to move things like carbohydrates

right across the actual what across the mitochondrial membrane these have to move in and out

because you'll talk later that we do a lot of different things like glycolysis has to occur inside of the mitochondrial

Matrix or gluconeogenesis has to occur inside of the mitochondrial Matrix right

we have to move things like fatty acids so we move things like fatty acids in here as well because they play a role in

something that we'll talk about later called beta oxidation right we have to move things like amino acids in here

right because they may play a role in something called the urea cycle and so there's a lot of different things that

are actually moving across this cell membrane and that's a really really important point that there's a lot of

ions that are moving across ions and small macromolecules that are moving across the mitochondrial membrane very

very key and again I think one of the big things to understand here is if they were to ask you a question regarding the

transport of things across the mitochondrial membrane which of the membranes is very permeable outer and

which one is very little permeability inner membrane so a big thing to take away

okay now we come on to the next component here the next component that I want you guys

to understand that is very critical to the function of the mitochondria and oftentimes what it's referred to with

that big buzzword term is the PowerHouse of the cell produces ATP ATP is power energy right so this electron transport

chain is huge and it's found primarily on the inner membrane so you don't really see this involved in the outer

membrane primarily in our membrane and we're not going to go into crazy detail of all the different processes

that are occurring on the electronic transport chain we're going to talk about that in the biochemistry or

metabolism playlist if you guys want to go watch that we have a playlist where we go through the electron

transportation in depth and we do an overview of it but the basic concept here is that you have these protein

molecules and they make up these different complexes like complex one complex two complex three complex four

and a very special molecule called ATP synthase and what happens with these

is that they take things you know you have your Krebs cycle and so from your Krebs cycle you take a molecule called

pyruvate right pyruvae gets converted into acetyl COA

and then acetyl-coa goes through this special thing called the Krebs cycle so this is called your Krebs cycle

and from the Krebs cycle which occurs in the mitochondria we form these high energy electron Transporters called

fadh2 and nadhs and they're carrying with them a lot of electrons in the form of like they have them in a hydrogen

what's called a hydride ion and what they do is they take and they transport these electrons onto these proteins and

they drop the electrons off in them and then these guys pass these electrons down the chain from areas of high energy

to areas of low energy and what that does is with each time that that happens it pumps all these protons out into the

inter membrane space pumps all these protons out into the intermembrane space and you guys

remember what I told you was very very rich and intermembrane space I said it for a

reason it's protons and then these protons what they do is they move from areas of in this

situation they move down this ATP synthase and they move down pretty powerfully and what it does is is it

moves down this ATP synthase it creates this energy that the protein can Harvest and when it harvests all that energy

what it allows it to do is is naturally something is bound to this and it's called ADP

and an inorganic phosphate they're kind of stuck to this this ATP synthase but as the protons run down this gradient as

electrons are being passed down it creates this energy that fuses these puppies together and then what it does

is it releases it in the form of ATP and this process where we make ATP via the electron transport chain is a very

specific type and we call this type of ATP production oxidative phosphorylation phosphorylation so a

really really key component here that's happening in this particular inner membrane

one side effect though that comes from these reactions is that all these electrons that are getting passed along

the membrane Sometimes some of these electrons that are really really rich out here

they can actually combine with things like oxygen and they can combine with other molecules and they can make things

like hydrogen peroxide or they can make superoxide free radicals so they basically can increase the formation of

things called reactive oxygen species which is that unfortunate side reaction from the electron transport chain that's

something that can happen as a side reaction of the electron transport chain so again

three functions to take away from the inner and outer membrane outer membrane highly permeable inner membrane less

permeable they allow for miscellaneous things to travel in and out of the mitochondria specifically for metabolic

reactions things like carbohydrates things like amino acids things like fatty acids and we'll talk about those

reactions in a second they also allow for unfolded proteins that are made by the nucleus by

ribosomes in the cytoplasm to be transported into the mitochondria so that they can use them for their

functions they don't make all the proteins that they need they really only make like 15 of the proteins and enzymes

that they need so they need a lot of proteins from from the actual nucleus and the last thing is they have the

electron transport chain specifically on the inner membrane and what does it do it takes high energy electrons from

nadhs fadh2s which are generated from metabolic reactions passes it on to those things they pass the electrons

down this chain and pump protons into the inter membrane space and then allows for it to flow back down into the

mitochondrial Matrix harvesting energy to make ATP via oxidative phosphorylation then an

unfortunate side reaction that can occur from the electron transport chain is you can make reactive oxygen species

unfortunately all right my friends let's now go into a little bit more

detail of what are these reactions that occur in the mitochondrial Matrix we've like clipped off a few of these like

okay there's you know the Krebs cycle there's gluconeogenesis I already said those terms there's the urea cycle

there's fatty acid oxidation some of these things that I've said we're going to kind of quickly go over them and talk

about how they're involved particularly in the mitochondrial Matrix so that if you're asked which of the following

reactions occur in the mitochondrial Matrix and you'll see this when we get into biochemistry you can pick out which

one it is likely that's going to be occurring there all right and then we'll briefly talk finishing about

mitochondrial DNA and we'll talk about ribosomes let's get over there and talk about that all right guys so now we're

going to talk about the next component here which is the functions involved in the mitochondrial Matrix so we went over

the inner membrane and outer membrane how they're particularly involved in things like protein transport

miscellaneous transport of things like nutrients as well as some ions and on top of that we went over the electron on

transport chain a really really big function for ATP production via oxidative phosphorylation

well the Matrix really what's cool about this is that we already kind of gave a little leeway or

kind of like introduced this slightly that there's a lot of metabolic reactions that can occur in the

mitochondria so really what I'm looking at inside of this red membrane here can pretend that this is the combination of

the inner outer membrane and the inter membrane space this is just the entire mitochondrial membrane here and then in

this is going to be your mitochondrial Matrix and that here is going to be your cytoplasm inside of the cell so this is

all cell but we're just zooming in on the mitochondria particularly The Matrix inside there and then the cytoplasm all

out here okay so what's cool is you know whenever you take something

like glucose so you bring glucose into the cell right so let's say that you bring glucose into the cell what we know

is that once glucose gets into the cell it eventually gets converted into something called pyruvate via glycolysis

and then that pyruvate will get brought in to the actual mitochondria when pyruvate is brought into the

mitochondria it then undergoes a conversion into a specific molecule called acetyl COA

and then acetyl-coa will go through these series of like steps which I don't want to talk about every single

substrate we'll do that later in Biochemistry but this process where it goes through this cycle is called the

Krebs cycle and so what you're seeing is two particular reactions that are occurring

here so far one is you're seeing the conversion of pyruvate into acetyl COA and the second thing you're seeing is

the Krebs cycle and we already briefly talked that coming off of the Krebs cycle is those high energy molecules

that carry electrons called nadhn fadh2 and these go to the electron transport chain where they pass off

those electrons pump protons into the inter membrane space and they help to generate something called ATP via

oxidative phosphorylation well what's another reaction that can occur here there's another cool one you

know whenever we take something like fatty acids so fatty acids these are just long chains like sometimes these

suckers can be like 16 carbons long we can bring these in to the mitochondrial Matrix across the membrane

so that's another example of Transport across that and then they can go through these series of metabolic reactions

where they get broken down into acetic OA and then you can use them to make energy

this step here is called beta oxidation this is another one of the reactions that takes place inside of the

mitochondria Matrix so so far we have the conversion of pyruvate into acetyl COA the Krebs cycle and then beta

oxidation of fatty acids what else can occur here there's another really cool one

you know when you take something like amino acids amino acids can get brought into the mitochondria as well

and what happens is amino acids eventually they can get metabolized into something called ammonia right so they

can actually get metabolized and when they get metabolized they give way to products in the Krebs cycle we're not

going to mention which ones but when it does do that it can give off something called ammonia

and ammonia is really really toxic really nasty son of a gun that you don't want to have to deal with

so what happens is ammonia will go through these like series of reactions here

and it's called the urea cycle and what happens is it liberates this molecule called urea Which is less toxic in

comparison to the ammonia and it's easier to be excreted but this cycle here this cycle that occurs kind of in

the What specifically in the mitochondrion even a little bit if you notice over here even a little bit of

the cytoplasm What's this called This is called the urea cycle so this is called the urea

cycle that's another metabolic reaction that takes place where

in the mitochondrial Matrix another one another reaction that's really cool is I

can take something like amino acids I can take something like odd chain fatty acids and I can convert them into

specific substrates but then what I can do which I'm going to represent here with a let's do it with a pink Arrow

is I can convert them back into pyruvate and then back into glucose you know what this is called when you

take something like an amino acid and not chain fatty acids and make glucose from it it's called gluconeogenesis

so that's another reaction which I'm going to represent kind of going in this with the Pink Arrow so I'll represent it

right here as the fifth reaction this is called gluconeogenesis okay so that's another one and then

there's one more reaction from the Krebs cycle you can take some of these intermediates

and make something called heme and some of these molecules of heme are actually synthesized in two

places they can actually be synthesized in both the mitochondrial Matrix

and they can be synthesized in the cytoplasm so both of these so we can make

something called heme there's another reaction so what's that one that's the sixth one so what I'm trying to tell you

here is there are so many metabolic reactions that take place within the mitochondrial Matrix what are some of

them if we were to again recap them we call these reactions first one is pyruvate to acetyl-coa

that's one particular reaction the second one that is also really important here is the Krebs cycle

that's another particular reaction Krebs cycle the third type of reaction here that

also occurs is going to be and I actually made it a two but that should be a three I apologize this is beta

oxidation so this is breaking down fatty acids so the third one should be beta oxidation of fatty acids so we'll put

beta oxidation there's actually another one here

so we go three we go four this is the urea cycle so this is the urea cycle but another big thing that I want to add

on here is that urea cycle can occur in two places as you're noticing by this reaction it

can occur in the mitochondria but it can also occur where and the cytoplasm

another particular reactions beside this one as we go to Five is this involved in what's called gluconeogenesis

this is called gluco neogenesis and what is gluconeogenesis it's taking something like amino acids

or taking something like odd chain fatty acids and converting them back into glucose but did you notice that this one

also takes place in the mitochondria and it also takes place in the cytoplasm another particular reaction is taking

something like Krebs cycle intermediates and making heme and it's involved in two particular places where it's involved in

the mitochondria and in the cytoplasm so that's another particular reaction which is heme synthesis

heme synthesis and again we can find this in two particular places both the

mitochondria and the cytoplasm usually to remember these

combo I remember hug heme synthesis urea cycle and gluconeogenesis as a little mnemonic there is technically one last

one if you really wanted to remember I could take acetyl coase and I could shunt them into making something called

ketones and that would be the last particular reaction that could occur inside

of the mitochondrial Matrix would be something called keto Genesis ketogenesis

so you can see there is a lot of metabolic reactions that take place inside of the mitochondria a massive

amount it's insane I don't expect you to remember every single one of these steps here the big thing I want you to

understand is that the mitochondria is involved in a ton of metabolic reactions that if you try and remember this now

it'll be helpful whenever we get into biochemistry and you'll see a lot of these reactions take place over and over

and over again that we'll go over all right so this is the big thing I want you to take away from this aspect

of the mitochondrial Matrix let's come down and talk about a couple more things with the mitochondria

so so far we got protein transport miscellaneous transport electron transport chain we got a lot of

metabolic reactions seven of them with three of them hug hug heme synthesis urea cycle and gluconeogenesis occurring

in both the mitochondria and cytoplasm the last thing is that this son of a gun can be involved in apoptosis it's

actually pretty crazy I'm not going to go too crazy with this we'll talk about a more detailed cell pathology but

whenever there's some type of process where a cell is infected or is cancerous or it needs to die unfortunately it has

to die there's special molecules present called cytochrome C and it's located inside of the mitochondrial Matrix

now naturally we don't want these things to be leaking out so there's proteins called like bcl2

that really help to prevent this from occurring but what happens is in apoptosis you

decrease the number of these and so now we can't control these cytochrome molecules from leaking out

and the cytochrome C molecules which is supposed to be kept in the mitochondrial Matrix leaks out

and these are nasty molecules because what they do is these cytochrome C molecules they

activate these enzymes called caspases and these are basically proteases and they just

start ripping through a bunch of different cells and so they start just damaging cell membrane damaging

organelles and eventually cause the cell to undergo its death process okay so it'll lead to a lot of signaling process

that will trigger it's programmed cell death that's what apoptosis is it's programmed

cell death okay my friends let's move on to the last particular function here for

mitochondria and that's pertaining to the DNA and the ribosomes what do they really do it's not too hard to

understand it's that here's our mitochondrial DNA with this I could do two things with it one is I can make

more of it what's that called DNA replication this could be important if I want to take maybe and replicate my

actual mitochondria so if I want to take this mitochondria and maybe undergo what's called a fission process and make

two of these puppies here let's say that I wanted to make two of these mitochondria I would want them both to

contain an equal amount of mitochondrial DNA you know what's super interesting believe it or not so

fission is a process where bacteria prokaryotic cells undergo division there's a theory

um back in the day called well it's still there it's called the endosymbiotic theory

the mitochondria back in the day used to just be a bacterial cell a prokaryote and it would have its own DNA and then

what happened is it got engulfed by a eukaryotic cell and then when it got engulfed inside of the eukaryotic cell

it then became something called a mitochondria and so it kind of started down regulating a lot of its genes and

proteins and stuff like that and the nucleus of a eukaryotic cell became the new Factory of DNA and it has it

cytoplasm to make many of the proteins that are needed and the mitochondria just primarily kind of got downgraded to

producing ATP and having some metabolic reactions occur in it so that's something called the endosymbiotic

theory but that's a really cool concept that basically the mitochondria used to be something called prokaryotic cells

and they just got engulfed by eukaryotic cells and they got downgraded to becoming a mitochondria which is kind of

interesting but that's one thing is we can kind of replicate them to make more of these types of mitochondria via

process called fission the other concept here is that we can take this mitochondrial DNA and undergo

transcription and we undergo transcription this makes something called RNA and these RNA molecules

combined with the ribosomes located in the mitochondria and here's another important Point these ribosomes are

called 70s ribosomes you know what they are in the the cytoplasm of eukaryotic cells which we'll talk about soon

they're ads that's another question they could potentially ask you so watch out for that but from this mitochondrial DNA

can replicate to undergo division of the mitochondria or it can make RNA and that's really important because you need

the DNA to make RNA you need the RNA to be translated and the translation process will then synthesize

particular types of proteins and these proteins that it makes generally accounts for about 15 percent of the

proteins that are needed for the mitochondria to be able to perform its functions so that means it needs a

decent chunk about 85 of the proteins to come from the nuclear DNA nuclear RNA than to get translated by the cytosolic

ribosomes and they get transported across the mitochondrial membrane so that it has those functions that's a

really cool concept and my friends that finishes off our discussion on the mitochondria their structure their

function I hope it made sense I hope that you guys take again the step-by-step process we go through the

inner outer membrane we went through the inter membrane space talked about their involves in protein transport the

electron transport chain and the miscellaneous transport and then we dug into the Matrix a little bit and then we

talked a little bit about how the mitochondrial DNA are involved in replicating itself for the actual

mitochondria to divide or making proteins via transcription translating those by ribosomes in them 70s ribosomes

to make proteins for it to function we also talked about all the metabolic reactions that are plentiful and

occurring inside of the mitochondria Matrix I hope it made sense and as always the engineers until next time

[Music] thank you