Understanding the Structure and Function of Peroxisomes: Key Organelles in Cellular Metabolism

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

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

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peroxisomes really cool organelles so they're kind of a spherical membrane so they have a membrane that encloses their

actual contents inside of them and they have four particular functions this is what I want you to remember so they're

Hollow spherical very interesting organelles that again play a role in four particular functions one is fatty

acid oxidation second one hydrogen peroxide metabolism third one ethanol metabolism and the fourth one is

biosynthetic function of particular lipids all right first one fatty acid oxidation all we do with fatty acid I

don't want to get too crazy here because we'll cover this more in Biochemistry but fatty acids can actually naturally

be metabolized by a very cool organelle that we've already discussed called the mitochondria so we talked about the

mitochondria we said one of the things that occurs is something called beta oxidation and then the mitochondria all

it means is we take this fatty acid into the mitochondria and it goes through this process of oxidation hydration and

again more oxidation and then with something called violation and you make something called a acetyl COA and then

what happens with acetyl-coa is generally in the mitochondria it'll go through the electron it'll actually go

through the Krebs cycle generate any of the H's F adh2s and then from there you can make something like uh energy well

particularly fadh2s nadh is they can utilize in the electron transport chain to make ATP

this is beta oxidation that occurs here so when we take this fatty acid we make acetyl COA this is called beta oxidation

now the same thing can happen in peroxisomes but in peroxisomes these are called very

long chain fatty acids and then over here we have another one called Branch chain fatty acids these will actually

get taken into peroxisomes and what happens is the very long chain fatty acids they'll go through the same kind

of process where they'll literally go and they'll make something called acetyl-coa right so you'll break them

down into two carbon chains at a time and when that happens again this process here is called beta oxidation so they

can occur in both the mitochondria and the peroxisomes big thing is for peroxisomes it occurs too very long

chain fatty acids and again this the basic concept is you do eye oxidation hydration oxidation and something called

violation we'll talk about that a little bit more in Biochemistry the other thing is the branch chain

fatty acids so the branched chain fatty acids when they get brought into the actual peroxisome they actually go and

you cut those branches off so when you cut the branches off to turn them into a very long chain fatty acid with no

branches on them this process is called Alpha oxidation so there's two particular process that are going to

occur here in the actual peroxisomes one is beta oxidation a very long chain fatty acids and the second one is Alpha

oxidation of branched chain fatty acids into very long chain fatty acids and what's the end goal here you cut these

things off two pieces at a time these very long chains you cut them into two carbon segments called acetyl COA and

generally you make something called a seal COA which is just a long again carbon chain so this was 16 carbons it

would be 14 carbons and these generally they just go back up and they continue this this vicious cycle until you've

broken the entire fatty chain down this is important particularly in which organelle and peroxisomes

so one of the functions of peroxisomes is to break down very long chain fatty acids into acetyl COA and then usually

one of these molecules that's again just two carbons shorter of this very long chain fatty acid and it gets recycled

and goes back down or you take Branch chain fatty acids and cut the branches off and make it into very long chain

fatty acids it'll just go down the cycle that's called Alpha oxidation okay beautiful

the second function that I want you guys to understand here is hydrogen peroxide metabolism

actually really interesting so in the same concept here you take in these molecules here so we're going to call

one of these this is our Branch chain fatty acid this is the one and we said we also bring the other one in which is

the very long chain fatty acids we said that generally these will undergo a beta oxidation process and what

happens is you make something you make two molecules right one is you make acetyl

COA and the other one is you make a seal COA and we said all that does is it just goes back and gets recycled right this

process here is called beta oxidation the next one is we take the branch chain

fatty acids and we break them down into very long chain fatty acids this is called Alpha oxidation we already talked

about this is occurs and peroxisomes what's really interesting is that in order for us to be able to

take these very long chain fatty acids and to do this process here to make these two molecules we actually have to

use water during the hydration or hydrolysis step and what that does is that takes water and oxygen and uses it

in this step to make something called hydrogen peroxide hydrogen peroxide hydrogen peroxide is

actually a nasty free radical so it has the ability to cause free radical molecules which cause a lot of damage to

proteins and DNA and membranes so we don't want this thing to form this is bad

so how do we actually prevent this thing from continuing to form well we got this cute little enzyme here you see this

pink enzyme this pink enzyme is called a catalase this is called a catalase enzyme and

what catalase does is is it takes the hydrogen peroxide that was formed and just converts it right back into water

and oxygen so we take the free radical which is nasty and turn it back into water and oxygen which is actually okay

and that makes you happy right so that's the big things that I really want you to remember here

for this particular molecule is the Catalyst the same thing you can actually take from you know what's called your

electron transport chain from your electron transport chain when you take fadhs and nadhs these will actually work

on the electron transport chain and generate things like free radicals one of them is hydrogen peroxide and these

hydrogen peroxide molecules can actually go here and get converted into water and oxygen as well this is really important

for preventing free radicals so again one thing I want you to remember here is that hydrogen peroxide is what we refer

to as a free radical and it can cause a lot of damage so this has the ability to damage

proteins and cell membranes and DNA we do not want that so that's what peroxisomes help to prevent

okay so we got fatty acid oxidation beta of long uh beta oxidation a very long chain Alpha oxidation of branched chains

we got hydrogen peroxide metabolism via catalasees and preventing free radical reactions what are the other two

functions the other two functions my friends are actually pretty cool and they kind of

coordinate with something called the smooth ER which you guys better remember so you guys remember the smooth

endoplasmic reticulum we said that one of the functions that they play a role within lipid synthesis

right they synthesize phospholipids they synthesize steroids particularly steroid hormones right well they can actually

derive from cholesterol so you can take cholesterol you can make steroid hormones sex hormones bile salts

lipoproteins all that stuff peroxisomes actually have the ability to do that as well so one of the things I want you to

remember is the smooth endoplasmic reticulum does help with making things like what

it does synthesize things like phospholipids they do help to synthesize things like

cholesterol and they also do help to synthesize a lot of other different things like fatty

acids right but I think this is the big thing to take away is the cholesterol and the phospholipids and then from

cholesterol you can synthesize a bunch of different things steroid hormones bile salts Etc

well in the same concept peroxisomes actually have that ability to do that as well so here's a peroxisome right

from this peroxisome what I can do is I can bring in again these molecules that we talked about the very long chain

fatty acids and the branch chain fatty acids what is this process called we're going to hit this so many times you guys

won't forget it this is called Alpha oxidation where we cut the branches off then we do this and we break these down

into something called acetyl COA and then you can actually recycle this

molecule this acetyl COA or you can make this other molecule here called a seal COA and this can actually

get recycled and continue to go down what's this process called going down this is called beta oxidation

now one of the cool things is that from this acetyl COA I can actually use this to synthesize a

particular molecule I can take the acetyl-coa and I can synthesize something called

what I can actually synthesize I can synthesize cholesterol

and you know what I can do with that cholesterol I can make a couple of different

molecules I can make bile salts or bile acids I can make steroid hormones

steroid hormones just in the same way that the smooth endoplasmic reticulum takes and

makes phospholipids it makes cholesterol from the cholesterol you can make things like bile

and steroid hormones it's the same concept

so we can take the cholesterol that you get from acetylcholate and make steroid hormones or make bile salts isn't that

pretty cool the other thing is I can take this acyl COA which is basically just a fatty acid that's all it is it's

really just a fatty acid it's just a shorter chain of it and what I can do is I can add on things like phosphates

I can add on things like phosphates to it and then convert this into what's called a phospho

lipid and there's one specific fossil because when we talk about peroxisomal disorders

for a U.S Middle East step one for the pathology point the one particular type of phospholipid is called plasmallogen

you know what plasmallogen is actually used in it's used in making myelin so we can actually synthesize phospholipids we

can synthesize cholesterol which can be used to make bile salts and steroid hormones so do you see how with just

this peroxisome from the breakdown products of fatty acid oxidation I can make phospholipids

I can make cholesterol and then subsequently the actual formation of cholesterol I can use it to make bile

salts steroid hormones and the other concept here is that not only is involved in the phospholipids

and cholesterol synthesis it's also even been shown to be involved in the activation of bile salts so you can add

that one in there as well as that it may also be involved in the activation of Basil it's not just the synthesis of

them but also the activation of them in other words your smooth ER helps to be able to make bile

acids not only does your peroxisomes do that as well but they may come in and the peroxisomes may have particular

enzymes that will stimulate or activate those bile acids so that's the last thing so biosynthetic functions my

friend what do I need you to remember they have functions similar to the smooth ER they can help to synthesize

phospholipids from the breakdown products of fatty acid oxidation such as

plasmallogen I really need you to remember that one it's used in making myelin which is important for our CNS

the next thing is you can also use the breakdown products of acetyl-coa to make cholesterol which can then be used to

make steroid hormones or bile acids and the last thing is we can even activate bile acids that come from the smooth ER

that's what I want you to remember okay the last and final function of the peroxisomes is ethanol metabolism

you know uh one of the interesting things here is that the smooth ER is involved in ethanol metabolism right we

know that the cytochrome p450 system so you know that ethanol is metabolized by the cytochrome p450 system in the smooth

endoplasmic reticulum we know that so if we take something like ethanol and it moves through the smooth ER the actual

cytochrome p450 system can metabolize this alcohol and it can convert it into particular metabolites that we're not

going to go into at this moment all right but in the same concept the peroxisomes also have that ability so

you can have alcohol get metabolized by multiple Pathways it could be metabolized by the cytochrome p450

system and the smooth ER but guess what else you can have it be metabolized by this

pathway as well so this is going to be another quick recap so brainstain fatty acids they get metabolized into what

very long chain fatty acids these also get brought in very and this is called Alpha oxidation very long chain fatty

acids get broken down into what we said one of these things is called acetyl COA and the other one is called the acyl

COA which then goes back up here this process is called beta oxidation

now one of the big things here is that we have Alpha oxidation bait oxidation what else did we say happens in this

process another thing that happens in this process here is we take water and oxygen and you convert it into

hydrogen peroxide and then we use this beautiful enzyme here called catalase

and this catalase will take and convert the hydrogen peroxide back into water and oxygen

it's actually really really important because we can use the hydrogen peroxide from the catalase enzyme to break down

ethanol so if I get ethanol so here's my ethanol that I decide to consume I can actually

break this down into a particular intermediate we call this aceta aldehyde

it's called acetylaldehyde acetyl-aldehyde and what happens is eventually this gets

broken down to acetyl COA and then you can use this for many different Pathways so in order for us to be able to again

convert the ethanol into acetaldehyde we actually have to use this Catalyst enzyme and it takes the hydrogen

peroxide and converts it into water and oxygen we already know that that's this enzyme this beautiful catalase enzyme

that helps with this particular process so when you think about it the catalyst is the primary enzyme of the peroxisomes

it helps to be able to convert hydrogen peroxide into water and oxygen reducing free radical formation it also is

important because water and oxygen are used in fatty acid metabolism bad beta oxidation particularly so we need that

water and oxygen to actually make hydrogen peroxide and then we use this enzyme to keep regenerating it so

catalase is indirectly involved in fatty acid oxidation it's directly involved in hydrogen peroxide metabolism it's

directly involved in ethanol metabolism isn't that pretty cool so I think that's an interesting process to understand

here but that is really the big things that I want you to understand about peroxisomes again they're Hollow

spherical vesicular types of organelles they have a membrane that encloses them inside them are many different enzymes

but the most important enzyme is catalase and the function of the peroxisome is as follows fatty acid

oxidation Alpha Beta biosynthetic functions of phospholipids the most particular one is plasmalogen

which is important for myelin of the CNS and cholesterol into the derivatives of that steroid hormones as well as bile

acids they may even activate bile acids and they're also involved in hydrogen peroxide metabolism and ethanol

metabolism via the catalase directly all right Engineers I hope this video made sense I hope that you liked it and as

always until next time [Music] thank you