Metabolism | Cholesterol Metabolism

00:28:10
https://www.youtube.com/watch?v=nurZ2nNovp8

Resumen

TLDRSelles videos käsitletakse kolesterooli ainevahetust, mis on oluline protsess, kuna kolesterool on paljude kehale vajalike ainete, nagu sapisoolad, steroidhormoonid ja lipoproteiinid, ehituskivi. Kolesterooli süntees toimub peamiselt maksas ja selle aluseks on atsetüül-CoA molekulid. Protsessis osalevad mitmeid ensüüme, sealhulgas HMG-CoA reduktaas, mis on väga oluline ja reguleeritud etapp. Selle etapi inhibeerimiseks kasutatakse statiinravimeid, mis on mõeldud kõrge kolesteroolitaseme alandamiseks. Kolesterool osaleb ka rakumembraanide moodustamises, steroidhormoonide tootmises ning lipoproteiinide ja bile soolade sünteesis, mis aitavad rasvade emulgeerimisel ja transpordil kehas.

Para llevar

  • ✅ Kolesterool on aluseks paljudele olulistele biomolekulidele.
  • 🧬 Kolesterooli süntees toimub peamiselt maksas.
  • 🔄 HMG-CoA reduktaas on kriitiline ensüüm kolesterooli sünteesis.
  • 💊 Statiinid vähendavad kolesterooli sünteesi, inhibeerides HMG-CoA reduktaasi.
  • 🏗️ Kolesterool mängib olulist rolli rakumembraanide struktuuris.
  • 🔍 Kolesterooli reguleeritakse kehas rangelt, et vältida ületootmist.
  • ⚖️ Insuliin ja glükagoon mõjutavad kolesterooli sünteesi tasakaalu.
  • 📦 Kolesterool pakendatakse lipoproteiinidesse transportimiseks.
  • 🌿 Kolesterool osaleb steroidhormoonide ja bile soolade sünteesis.
  • 🛡️ Kolesterooli transport ja tasakaal on keha tervise jaoks kriitilise tähtsusega.

Cronología

  • 00:00:00 - 00:05:00

    Video räägib kolesterooli metabolismist ja selle olulisusest organismis. Kolesterool on vajalik sapisoolade, steroidhormoonide ning rakumembraanide koostises. Samuti on oluline kolesterooli transport lipoproteiinide abil. Peamine kolesterooli süntees toimub maksas, alustades glükoosist, mis läbi mitmete biokeemiliste radade muundub atsetüülkoensüümiks A (acetyl-CoA).

  • 00:05:00 - 00:10:00

    Atsetüül-CoA liigse olemasolu korral suunatakse see erinevatesse radadesse, sealhulgas ketoonkehade ja kolesterooli sünteesi suunas. Kolesterooli süntees algab atsetüül-CoA-st, mis katalüüsitakse atsetoatsetüül-CoA-ks ensüümi tiolaasi abil. Jätkukatalüüsid ja ensüümid, nagu HMG-CoA süntaas ja HMG-CoA reduktaas, mängivad kriitilist rolli kolesterooli tootmises.

  • 00:10:00 - 00:15:00

    HMG-CoA reduktaas on kolesterooli sünteesi võtmeensüüm, mille aktiivsust reguleerivad nii insuliin kui statiinid nagu Lipitor. HMG-CoA muundamine mevaloonhappeks tähistab olulist metaboolset etappi. Juba mevaloonhape läbib mitmeid muundumisi, millest olulisim on squalene süntees, millest lõpuks moodustub kolesterool.

  • 00:15:00 - 00:20:00

    Kolesterooli saab rakendada mitmetes bioloogilistes struktuurides, sealhulgas rakumembraanides, vähendades membraani voolavust ja ennetades faasimuutusi. Samuti on kolesterooli võimalik sünteesida steroidhormoonideks nagu testosteroon ja östrogeen, ning samuti ka sapisooladeks, mis aitavad seedida rasvu.

  • 00:20:00 - 00:28:10

    Lisaks moodustatakse kolesterooli põhjal lipoproteiine nagu LDL ja VLDL, mis transpordivad kolesterooli erinevatesse kudedesse. Liigne LDL on tervisele kahjulik, ning selle reguleerimiseks kasutatakse statiine. Video rõhutab kolesterooli metabolismi olulisust ja keerukust, samuti selle reguleerimise tähtsust organismis.

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Mapa mental

Vídeo de preguntas y respuestas

  • Mis on kolesterooli metabolismi tähtsus?

    Kolesterooli metabolism on oluline, kuna kolesterool on aluseks sapisooladele, steroidhormoonidele ja lipoproteiinidele, mis on vajalikud keha erinevate funktsioonide jaoks.

  • Kus toimub kolesterooli süntees peamiselt?

    Kolesterooli süntees toimub peamiselt maksas.

  • Millist olulist ensüümi mainitakse kolesterooli sünteesil?

    HMG-CoA reduktaasi, mis on oluline ja reguleeritud samm kolesterooli sünteesi protsessis.

  • Kuidas mõjutab insuliin kolesterooli sünteesi?

    Insuliin stimuleerib kolesterooli sünteesi, aktiveerides seeläbi HMG-CoA reduktaasi.

  • Mis on statiinide funktsioon?

    Statiinid on ravimid, mis inhibeerivad HMG-CoA reduktaasi, vähendades seeläbi kolesterooli sünteesi.

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Desplazamiento automático:
  • 00:00:06
    iron engineers in this video we're going
  • 00:00:08
    to talk about cholesterol metabolism so
  • 00:00:11
    cholesterol metabolism is extremely
  • 00:00:13
    important because cholesterol is the
  • 00:00:14
    basic unit for a lot of different things
  • 00:00:16
    one of the things that we'll talk about
  • 00:00:17
    is four bile salts which are really
  • 00:00:19
    really important for being able to help
  • 00:00:21
    with the emulsification of large fat
  • 00:00:23
    globules that we take in through
  • 00:00:24
    ingestion they're also important for a
  • 00:00:26
    lot of the steroid hormones that we
  • 00:00:28
    utilize on our body like testosterone
  • 00:00:29
    progesterone estrogen vastra and
  • 00:00:31
    cortisol and they're also important
  • 00:00:34
    because they are actually packaged
  • 00:00:35
    there's specific molecules specifically
  • 00:00:37
    called lipoproteins and we'll talk about
  • 00:00:39
    a couple of them in this video we'll
  • 00:00:41
    have another video on more detail on
  • 00:00:42
    that but we'll talk a little bit about
  • 00:00:44
    how they're involved in actual transport
  • 00:00:47
    of cholesterol and then also it's a very
  • 00:00:48
    integral component of the membrane but
  • 00:00:50
    we'll talk about all that but the
  • 00:00:51
    significance of this whole video is to
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    see how we're going to be able to
  • 00:00:55
    synthesize cholesterol with a basic unit
  • 00:00:58
    of acetyl co a and how that can be used
  • 00:01:00
    for synthesis mechanisms we'll talk
  • 00:01:01
    about a couple enzymes along the way
  • 00:01:03
    okay so cholesterol metabolism is
  • 00:01:05
    primarily going to be occurring inside
  • 00:01:06
    of the liver we can take cholesterol in
  • 00:01:08
    through an exogenous pathway via through
  • 00:01:11
    the ingestion of foods and we can take
  • 00:01:12
    them transport them to different tissues
  • 00:01:15
    via what's called chylomicrons but the
  • 00:01:17
    endogenous pathway of cholesterol is
  • 00:01:19
    actually going to be taking place within
  • 00:01:20
    the liver so let's see how we do that
  • 00:01:22
    well if you guys remember from a lot of
  • 00:01:26
    these videos we could take a molecule
  • 00:01:28
    called glucose and we could take glucose
  • 00:01:32
    and what can we do with them if you guys
  • 00:01:34
    remember we could take glucose and we
  • 00:01:36
    could eventually convert that glucose
  • 00:01:38
    into pyruvate through glycolysis right
  • 00:01:40
    and then another thing we could do is we
  • 00:01:42
    could take that pyruvate and eventually
  • 00:01:45
    convert it into acetyl co a but what can
  • 00:01:50
    happen with the acetyl co if you guys
  • 00:01:51
    remember acetyl co a can actually go
  • 00:01:53
    through a specific sequence of cyclic
  • 00:01:55
    steps right which is called the Krebs
  • 00:01:58
    cycle and then from the Krebs cycle what
  • 00:02:00
    do you generate you generate a lot of
  • 00:02:01
    NADH is you generate a lot of fadh2s
  • 00:02:07
    even generate a little bit of ATP
  • 00:02:09
    through substrate phosphorylation but
  • 00:02:11
    these guys are generally taking their
  • 00:02:13
    information to thee what the electron
  • 00:02:16
    transport chain and what happens if the
  • 00:02:18
    electron transport chain you make ATP so
  • 00:02:22
    that is the overall goal of this process
  • 00:02:24
    right now what happens though whenever
  • 00:02:28
    we have too much acetyl co a what
  • 00:02:32
    happens if you guys remember the main
  • 00:02:35
    anabolic hormone I want you guys to
  • 00:02:37
    really really remember this one that
  • 00:02:39
    hormone was called insulin insulin is
  • 00:02:42
    the main anabolic hormone of the body
  • 00:02:45
    okay so insulin is extremely important
  • 00:02:48
    in this process of cholesterol
  • 00:02:49
    metabolism so what is he going to do
  • 00:02:51
    we'll talk about that in a second well
  • 00:02:53
    now let's see how this if there's too
  • 00:02:55
    much acetyl co a we already know that it
  • 00:02:57
    can go into two different pathways that
  • 00:02:59
    we talked about one was a tiny little
  • 00:03:01
    pathway we can say over here that we can
  • 00:03:03
    make ketone bodies if you guys remember
  • 00:03:05
    through ketogenesis
  • 00:03:06
    and then what can happen with these
  • 00:03:08
    ketone bodies if you remember they can
  • 00:03:10
    be taken up by two different specific
  • 00:03:12
    tissues the brain the central nervous
  • 00:03:14
    system tissue as well as the muscles and
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    can be utilized to make what they can be
  • 00:03:19
    utilized to make ATP but there's another
  • 00:03:25
    side pathway that we can push acetyl
  • 00:03:27
    COAS into and that is into a cholesterol
  • 00:03:30
    synthesis so now let's talk about that
  • 00:03:32
    so let's say that I take this acetyl co
  • 00:03:34
    a I put it right it'll actually no let's
  • 00:03:36
    bring it over here then let's say that I
  • 00:03:37
    take these acetyl co eggs and we start
  • 00:03:39
    here and see how this is all happening
  • 00:03:41
    so now acetyl co a let's say I take an
  • 00:03:44
    acetyl co a here and I take another
  • 00:03:48
    acetyl co a and I'm going to react these
  • 00:03:52
    two molecules together so I'm going to
  • 00:03:54
    take these two molecules and I'm going
  • 00:03:56
    to react them together so let's say I
  • 00:03:57
    react these two together and I'm going
  • 00:04:00
    to use them together when i fuse acetyl
  • 00:04:03
    co a and acetyl co a together there's a
  • 00:04:05
    special enzyme there's a lot of
  • 00:04:08
    different names for it but I like the
  • 00:04:09
    simple names it's easier for me to
  • 00:04:11
    remember so I like thiolase it's just an
  • 00:04:14
    easier time to remember as compared to
  • 00:04:17
    like acetyl co a acetyl transferase Idol
  • 00:04:20
    I just like the thiolase
  • 00:04:21
    okay but there is another enzyme that
  • 00:04:23
    you could utilize for this
  • 00:04:24
    step okay now in this step what am i
  • 00:04:29
    doing I'm taking a seat Ocoee and a CoA
  • 00:04:32
    and reacting them together in this first
  • 00:04:34
    step of the reaction but what am I going
  • 00:04:36
    to get out of this out of this I'm going
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    to produce a molecule called a cito
  • 00:04:43
    acetyl co a now this might seem very
  • 00:04:47
    very familiar if you guys have already
  • 00:04:49
    watched our ketone body videos the
  • 00:04:51
    actual beginning steps of this process
  • 00:04:53
    is going to be almost exactly the same
  • 00:04:55
    as the ketone bodies now we're not going
  • 00:04:57
    to go through every single step to make
  • 00:04:59
    cholesterol it's about 30 steps long so
  • 00:05:01
    to do that would be ridiculous we want
  • 00:05:03
    to get the significant components out of
  • 00:05:04
    this video but here's what we we need to
  • 00:05:07
    notice look at this we have acetyl co a
  • 00:05:10
    an acetyl co a how many of utica ways is
  • 00:05:12
    that that's I'm sorry how many Co ways
  • 00:05:14
    is that that's two Koei's then what I
  • 00:05:16
    did is I converted that into a cito
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    acetyl co a there's only one Co a there
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    so what did I lose in this stuff
  • 00:05:22
    I lost a co a so in this step I lost a
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    co enzyme a and I made a cito acetyl co
  • 00:05:30
    a now and the next step I'm going to do
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    this reaction and what I'm going to do
  • 00:05:36
    is I'm going to combine another molecule
  • 00:05:37
    and this next molecule is exactly the
  • 00:05:40
    same as what we had over here guess what
  • 00:05:42
    I'm going to have coming over here I'm
  • 00:05:43
    going to have a seat okole so I'm going
  • 00:05:45
    to feed another acetyl co a into this
  • 00:05:48
    reaction so now I'm going to take this
  • 00:05:50
    acetyl co a and feed it into this
  • 00:05:52
    reaction here okay so let's actually
  • 00:05:54
    show this in the same color then so that
  • 00:05:56
    we make it look all nice and Purdy
  • 00:05:58
    acetyl co a here with the acetyl acetyl
  • 00:06:01
    co a is going to react and what am I
  • 00:06:04
    going to do I'm going to lose another Co
  • 00:06:07
    a so out of this reaction what's going
  • 00:06:09
    to come popping out I'm going to pop out
  • 00:06:11
    a CO a now now I'm going to form a very
  • 00:06:18
    special molecule now there's two there's
  • 00:06:19
    actually two names for this the
  • 00:06:21
    abbreviation I'm just going to call it H
  • 00:06:23
    M G Co a but there is another name for
  • 00:06:30
    it I will mention it but it's easier to
  • 00:06:35
    do this one but it actually goes 3
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    hydroxy
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    three methyl blue Carol Calais or beta
  • 00:06:42
    hydroxy beta methyl gluten okay now you
  • 00:06:45
    guys probably get why I would just call
  • 00:06:46
    it a gym GK it's easier to say that but
  • 00:06:49
    the whole point is that we do have a
  • 00:06:50
    hydroxy group on the third carbon and
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    then we have a methyl group on the third
  • 00:06:54
    carbon and then it's a glute arrow kolay
  • 00:06:56
    okay what enzymes catalyzing this step a
  • 00:06:59
    very very important enzyme and this is
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    called hmg-coa synthase okay he is
  • 00:07:07
    catalyzing this stuff he's stimulating
  • 00:07:10
    this step to fuse acetyl coa with acetyl
  • 00:07:13
    co and make HMG coa now we go into the
  • 00:07:17
    most most important one of the most
  • 00:07:19
    regulated steps of all metabolism in the
  • 00:07:22
    entire body
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    okay let's make sure that we understand
  • 00:07:26
    that so I'm going to do this in a really
  • 00:07:27
    really thick red arrow here this is one
  • 00:07:31
    of the most regulated enzymatic steps in
  • 00:07:35
    the entire body
  • 00:07:38
    okay the enzyme that's regulating this
  • 00:07:40
    step here I specifically called h mg co
  • 00:07:45
    a reductase so hmg-coa reductase is the
  • 00:07:51
    rate limiting step here it's very very
  • 00:07:53
    important I'm going to put below it it
  • 00:07:55
    is the rate limiting step so it's one of
  • 00:08:03
    the slowest step it's one of the most
  • 00:08:04
    important and most regulated steps so
  • 00:08:07
    this is one of the most regulated steps
  • 00:08:09
    in our body here this step right here
  • 00:08:10
    why because it's very very crucial that
  • 00:08:15
    we regulate how much cholesterol is
  • 00:08:17
    being made so how do we do that well you
  • 00:08:22
    know you know there's actually drugs you
  • 00:08:24
    know people have really really high
  • 00:08:24
    cholesterol they have to take certain
  • 00:08:26
    types of drugs to be able to lower the
  • 00:08:28
    cholesterol you know how they actually
  • 00:08:29
    do it one of the drugs that you guys
  • 00:08:30
    have probably heard of called lipitor so
  • 00:08:33
    you've probably heard of the drug called
  • 00:08:34
    lipitor and we're like its branding the
  • 00:08:38
    lipitor lipitor is actually what's
  • 00:08:41
    called a statin so there's different
  • 00:08:42
    type of statins and statins are
  • 00:08:45
    basically just drugs that can come and
  • 00:08:47
    inhibit this enzyme
  • 00:08:49
    so this hmg-coa reductase could be in
  • 00:08:52
    by certain types of drugs which can
  • 00:08:54
    inhibit the cholesterol synthesis which
  • 00:08:56
    is good for people who have high
  • 00:08:57
    cholesterol levels they've been eating
  • 00:08:59
    too much Burger King too many whoppers
  • 00:09:01
    right so we need to cut that down take
  • 00:09:03
    their lipitor and watch what they're
  • 00:09:04
    eating but anyway this HMG co-reductase
  • 00:09:06
    is very very important because it's
  • 00:09:08
    what's controlling the conversion of HMG
  • 00:09:10
    calais and to another very important
  • 00:09:12
    molecule which is going to be the
  • 00:09:13
    precursor so this molecule is called
  • 00:09:17
    methyl on it Armel ilanic acids doesn't
  • 00:09:21
    matter I'm just going to call it neva
  • 00:09:24
    law neat so this next enzyme again is
  • 00:09:28
    called methyl on eight
  • 00:09:29
    now methyl on e is actually important
  • 00:09:32
    because he's going to be the precursor
  • 00:09:34
    for the synthesis of cholesterol now
  • 00:09:36
    like I said we're not going to go over
  • 00:09:37
    every single enzymatic step it's
  • 00:09:39
    ridiculous there's so many will come
  • 00:09:41
    some of the more significant ones like
  • 00:09:43
    you know mevalonic can actually be
  • 00:09:45
    converted into another molecule which is
  • 00:09:47
    called isopentyl pyrophosphate so that
  • 00:09:52
    molecule is called ISO pencil pyro
  • 00:10:00
    phosphate now why am i mentioning this
  • 00:10:02
    because whenever this methyl Ani he goes
  • 00:10:05
    through a couple steps and eventually
  • 00:10:07
    gets converted into isopentyl
  • 00:10:08
    pyrophosphate isopentyl pyrophosphate
  • 00:10:12
    is going to be kind of the building
  • 00:10:14
    block for this also because what happens
  • 00:10:16
    is I'm going to take a whole bunch of
  • 00:10:18
    different types of isomerase forms of
  • 00:10:21
    the isopentyl I saw pyrophosphate or
  • 00:10:23
    just the isopentyl pyrophosphate itself
  • 00:10:25
    and I'm going to combine a ton of them
  • 00:10:29
    I'm talking boatloads of these isopentyl
  • 00:10:32
    pyrophosphates and eventually I'm going
  • 00:10:35
    to form a very special molecule and this
  • 00:10:38
    process right here I'm completely
  • 00:10:42
    bypassing a lot of important information
  • 00:10:44
    here or I'm sorry not a lot of
  • 00:10:46
    information because you know just for me
  • 00:10:48
    to convert this isopentyl pyrophosphate
  • 00:10:49
    into this next molecule this next
  • 00:10:52
    molecule is called squalene
  • 00:10:57
    so isopentyl pyrophosphate technically
  • 00:11:02
    in between here if I were to actually
  • 00:11:04
    kind of have an in-between step here
  • 00:11:05
    isopentyl pyrophosphate let's actually
  • 00:11:08
    just do it here in this step I just do
  • 00:11:10
    here we say that we take the isopentyl
  • 00:11:12
    pyrophosphate and I take and I actually
  • 00:11:14
    convert that and to these molecules
  • 00:11:16
    which are called isoprene units I so
  • 00:11:22
    preen units and these isoprene units are
  • 00:11:26
    important because it takes a ton of
  • 00:11:29
    isoprene units to eventually get
  • 00:11:32
    converted into a very important molecule
  • 00:11:34
    called squalene okay so now we'll talk
  • 00:11:37
    about the scaling so squalene in order
  • 00:11:41
    for me so this is a complete
  • 00:11:43
    oversimplification because simply going
  • 00:11:45
    from these isoprene units to the scaling
  • 00:11:48
    can take up to 21 steps so let me write
  • 00:11:51
    that down because it's significant me
  • 00:11:53
    going just from the isoprene units to
  • 00:11:55
    the scaling it can take up to 21 steps
  • 00:11:58
    now one of the more important enzymes in
  • 00:12:01
    throughout this process green is called
  • 00:12:04
    squalene synthase and the squalene
  • 00:12:10
    synthase is an environments helping with
  • 00:12:12
    in these processes to convert these
  • 00:12:14
    isoprene units into squalene now
  • 00:12:16
    squalene is then going to be the
  • 00:12:19
    precursor to make another molecule and
  • 00:12:22
    this molecule is called 7d hydro
  • 00:12:29
    cholesterol so 7d hydro collector I
  • 00:12:32
    guess apply heard of that whenever we
  • 00:12:33
    talk about the parathyroid hormone with
  • 00:12:35
    toughly to make vitamin D so you can
  • 00:12:38
    actually make vitamin D from this point
  • 00:12:39
    here but look we're going to make
  • 00:12:41
    another molecule called 7d hydro
  • 00:12:43
    cholesterol then what happens at 7d
  • 00:12:46
    hydro cholesterol okay now here's where
  • 00:12:54
    we get into the good stuff so now this
  • 00:12:57
    7d hydro cholesterol what can happen
  • 00:12:59
    with this molecule there's 70 hydro
  • 00:13:02
    cholesterol I'm going to put this
  • 00:13:03
    squealing synthase under here that we
  • 00:13:05
    have some room to come back down again
  • 00:13:07
    this is called squalene synthase now
  • 00:13:13
    here's where it's important so let's
  • 00:13:15
    make this a really big line here
  • 00:13:17
    7d hydro cholesterol
  • 00:13:19
    can be converted into the molecule that
  • 00:13:22
    we know as cholesterol so in this
  • 00:13:26
    process here what am i doing I'm taking
  • 00:13:29
    the 7d hydro cholesterol and I'm
  • 00:13:31
    converting it into a molecule called
  • 00:13:33
    cholesterol now this cholesterol that
  • 00:13:39
    I'm making you it's crazy to see how we
  • 00:13:42
    just take these two carbon fragments
  • 00:13:43
    acetic aways and we synthesize a huge 27
  • 00:13:48
    carbon molecule like you would guys want
  • 00:13:49
    to know what I a cholesterol looks like
  • 00:13:51
    I'll tell you I know you guys are
  • 00:13:52
    excited you guys are chomping at the bit
  • 00:13:54
    to see the structure of cholesterol so
  • 00:13:56
    look here because I know you guys are
  • 00:13:57
    chomping at the bit for so look I'm
  • 00:13:59
    going to have three six carbon rings
  • 00:14:03
    like this right then I'm gonna have
  • 00:14:06
    another six carbon ring like this and
  • 00:14:09
    then I'm going to have a five carbon
  • 00:14:11
    ring like this then I like to put a
  • 00:14:13
    methyl right here and a methyl right
  • 00:14:16
    here
  • 00:14:16
    so now let's number all of these puppies
  • 00:14:19
    here this right here is number one two
  • 00:14:22
    three four then I'm going to come over
  • 00:14:26
    here to five six seven eight nine and
  • 00:14:31
    then I come to this last point here ten
  • 00:14:33
    okay
  • 00:14:34
    then I'm going to come up over here 11
  • 00:14:36
    12 13 I'm going to go over here 14 15 16
  • 00:14:42
    17 then we come over here
  • 00:14:46
    18 19 but I told you all the way exact
  • 00:14:49
    you said it was 27 it is 27 coming off
  • 00:14:52
    of the 17th carbon I'm going to have a
  • 00:14:54
    branch like that 1 2 3 4 5 so 1 2 3 4 5
  • 00:15:00
    and then like this and now let's count
  • 00:15:02
    these carbons over here 17 18 19 this is
  • 00:15:06
    going to be 20 21 22 23 24 25 26 27 why
  • 00:15:15
    am I telling you all this because
  • 00:15:17
    there's important points throughout all
  • 00:15:19
    of this on the third carbon there's a
  • 00:15:22
    special thing that's going to determine
  • 00:15:23
    the difference between certain types of
  • 00:15:25
    steroid hormones on that third carbon
  • 00:15:27
    there's usually a alcohol okay and then
  • 00:15:31
    in between the fifth
  • 00:15:33
    in the six-carbon there should be a
  • 00:15:35
    double bond so now I like to just call
  • 00:15:40
    this a ring the B ring C ring and the D
  • 00:15:45
    ring and then you got this little
  • 00:15:47
    antenna structure this is our
  • 00:15:48
    cholesterol molecule now we synthesize
  • 00:15:51
    this cholesterol what is this
  • 00:15:53
    cholesterol used for because it's
  • 00:15:56
    extremely important we said that it's
  • 00:15:57
    important to be able to take this
  • 00:15:58
    cholesterol and synthesize a bunch of
  • 00:16:00
    different structures so now let's take
  • 00:16:01
    this cholesterol and see what we can
  • 00:16:02
    actually do with this cholesterol okay
  • 00:16:06
    so I told you that I could take this
  • 00:16:08
    cholesterol molokai I'm not going to
  • 00:16:10
    drill every single carbon again I'm just
  • 00:16:12
    going to take this carbon unit so that
  • 00:16:13
    you can see that we have cholesterol
  • 00:16:15
    here and what we're going to do with
  • 00:16:18
    this cholesterol is we're going to take
  • 00:16:19
    this cholesterol and use it to make a
  • 00:16:23
    whole bunch of different molecules and
  • 00:16:24
    again we can if you want to a ring B
  • 00:16:27
    ring C ring D ring okay what I can do
  • 00:16:32
    with this cholesterol is I can put it
  • 00:16:36
    into the actual cell membrane you're the
  • 00:16:37
    cell membranes are really important why
  • 00:16:39
    why is the cell membrane important let's
  • 00:16:41
    say that I have here the cell membrane
  • 00:16:43
    and in the cell membrane here you know
  • 00:16:47
    we have phospholipids that are making up
  • 00:16:49
    the actual cell membrane if I were to
  • 00:16:50
    kind of zoom in on this a little bit
  • 00:16:52
    let's say here's my glycerol okay and
  • 00:16:56
    then coming on one side have the fatty
  • 00:16:58
    acids right but you know that this
  • 00:17:01
    specifically the cell membrane is a
  • 00:17:03
    lipid bilayer so on the other side I'll
  • 00:17:05
    also have another group of phospholipids
  • 00:17:10
    but now here's the important thing
  • 00:17:14
    phospholipids are you know they're
  • 00:17:17
    they're basically they can make things
  • 00:17:19
    not as fluid like but cholesterol is
  • 00:17:21
    making it better and not being so fluid
  • 00:17:23
    like making a little bit more rigid so
  • 00:17:26
    if I take this cholesterol molecule and
  • 00:17:28
    I put this cholesterol molecule into the
  • 00:17:30
    structure let's say I erased this part
  • 00:17:32
    here and I put my cholesterol molecule
  • 00:17:35
    in here so now what I do is I take my
  • 00:17:37
    cholesterol molecule and I incorporate
  • 00:17:41
    this cholesterol molecule into this
  • 00:17:46
    structure
  • 00:17:47
    what is that going to do what this does
  • 00:17:49
    is it's actually first off it does two
  • 00:17:52
    things two things that this does being
  • 00:17:54
    cool incorporate into the membrane one
  • 00:17:56
    is it makes the membrane less fluid like
  • 00:18:02
    Les like les fluidity less fluidity okay
  • 00:18:06
    that's one thing so it's going to make
  • 00:18:07
    it less fluid the other thing it's going
  • 00:18:10
    to prevent drastic changes in phase
  • 00:18:13
    transitions so changing from different
  • 00:18:15
    phases so it prevents it prevents phase
  • 00:18:23
    transitions you know it's another
  • 00:18:26
    important thing it's also combining with
  • 00:18:30
    a molecule that is present in this area
  • 00:18:32
    let's say here I have a molecule special
  • 00:18:34
    molecule that it's combining with to
  • 00:18:36
    form a very special structure what is
  • 00:18:38
    this green molecule here called this is
  • 00:18:40
    called glyco sphingo lipids
  • 00:18:46
    so these glycosphingolipids are
  • 00:18:49
    combining with the cholesterol and as a
  • 00:18:52
    structure they're forming this whole
  • 00:18:54
    thing here if I were to kind of encase
  • 00:18:56
    it here they're forming what's called
  • 00:19:00
    the lipid raft which is important in
  • 00:19:03
    certain types of signaling pathways as
  • 00:19:05
    well as a lot of other processes so
  • 00:19:07
    again what's one thing that we can do
  • 00:19:10
    with this cholesterol right away one
  • 00:19:11
    thing I can do with this cholesterol is
  • 00:19:13
    I can incorporate this cholesterol into
  • 00:19:15
    the cell membranes because it's
  • 00:19:17
    naturally in normal physiological levels
  • 00:19:20
    is helping the membrane become less
  • 00:19:22
    fluid helping it to be more rigid and
  • 00:19:23
    hold up its actual structure the other
  • 00:19:25
    thing is preventing excessive phase
  • 00:19:27
    transitions okay also it's combining
  • 00:19:30
    with these glycosphingolipids within the
  • 00:19:32
    cell membrane to form lipid rafts
  • 00:19:33
    structures which are important for a lot
  • 00:19:35
    of different functions like cell
  • 00:19:36
    signaling processes what else can we do
  • 00:19:38
    with the cholesterol so that's one thing
  • 00:19:40
    we can do with it another thing that we
  • 00:19:43
    can do with this is we can take and
  • 00:19:45
    convert it into steroid hormones steroid
  • 00:19:49
    hormones are very very important so I
  • 00:19:51
    can actually make steroid hormones what
  • 00:19:52
    kind of steroid hormones can I make you
  • 00:19:54
    know there's many many different types
  • 00:19:56
    of steroid hormones
  • 00:19:58
    we talked about some of them and
  • 00:20:00
    endocrine I can make testosterone I can
  • 00:20:06
    make estrogen I can make corticosteroids
  • 00:20:11
    which includes your out dosterone and
  • 00:20:13
    your cortisol I can make tons of
  • 00:20:15
    different things progesterone a lot of
  • 00:20:19
    different molecules that can come from
  • 00:20:20
    this right so we can make steroid
  • 00:20:21
    hormones we can make progesterone
  • 00:20:23
    testosterone estrogen a lot of different
  • 00:20:25
    corticosteroids like cortisol AB astron
  • 00:20:27
    can add a corticoids so many different
  • 00:20:29
    types of things that we could do with
  • 00:20:30
    this so that's another basic unit for
  • 00:20:34
    the cholesterol so cholesterol can be
  • 00:20:36
    used for its cell membrane structures
  • 00:20:37
    steroid hormones what how it's going to
  • 00:20:39
    be used for it also could be used for
  • 00:20:43
    bile salts you know there's these things
  • 00:20:45
    called bile salts and these vile salts
  • 00:20:47
    are important because bio salts are
  • 00:20:51
    important you know there's let's call
  • 00:20:52
    Kolok acid there's called Kolak acid and
  • 00:20:55
    then there's another one called
  • 00:20:57
    deoxycholic acid and these are bile
  • 00:21:02
    salts and they're important for what you
  • 00:21:04
    know they're important we actually make
  • 00:21:06
    this in the liver and they're
  • 00:21:07
    incorporated into the bile which is
  • 00:21:08
    excreted into the small intestine like
  • 00:21:10
    specifically the duodenum what does that
  • 00:21:12
    help for it it helps with the
  • 00:21:14
    emulsification of lipids you know taking
  • 00:21:21
    lipids that are very very water
  • 00:21:23
    insoluble and trying to make them more
  • 00:21:25
    water-soluble by spreading them out into
  • 00:21:27
    smaller fatty droplets that we'll talk
  • 00:21:30
    about called me cells okay and a lasting
  • 00:21:33
    we'll have another video specifically on
  • 00:21:36
    this in detail but you know what else we
  • 00:21:39
    can do with that cholesterol we can
  • 00:21:41
    package this cholesterol and we can send
  • 00:21:44
    it to other tissues so I can actually
  • 00:21:46
    package this cholesterol and to do
  • 00:21:48
    special lipoprotein molecule so let's
  • 00:21:51
    say I take that cholesterol but you know
  • 00:21:53
    in order for me to take this cholesterol
  • 00:21:54
    and put it into this actual vesicle I'm
  • 00:21:57
    sorry this lipoprotein structure I need
  • 00:21:59
    a special enzyme and this enzyme is
  • 00:22:01
    called a cat
  • 00:22:05
    and a cat is an enzyme that basically
  • 00:22:08
    converts cholesterol into a cholesterol
  • 00:22:10
    ester so again what what am i convert so
  • 00:22:12
    if you guys remember here on the a on
  • 00:22:14
    that third carbon I had an alcohol what
  • 00:22:18
    I'm going to do is I'm going to take in
  • 00:22:19
    this vesicle here I'm going to convert
  • 00:22:23
    inside here I'm going to take and I'm
  • 00:22:25
    going to basically take and add an acyl
  • 00:22:27
    group onto it so you know a cat is
  • 00:22:30
    basically an ACO Co a and specifically
  • 00:22:34
    what I'm doing here is I'm transferring
  • 00:22:36
    on a a so group so in other words let me
  • 00:22:39
    show you what I'm doing here so I'm
  • 00:22:41
    going to take that actual group here I'm
  • 00:22:43
    going to put on a double bond like I see
  • 00:22:47
    CH 3 there so let's say I add on a 2
  • 00:22:49
    carbon group there now this is a
  • 00:22:50
    cholesterol ester and if I were to draw
  • 00:22:52
    the rest of the structure here you guys
  • 00:22:54
    would get the point here that basically
  • 00:22:57
    I'm packaging this molecule into a nice
  • 00:23:01
    big vesicle so let me draw a big vesicle
  • 00:23:04
    here lipoprotein molecule so now this
  • 00:23:07
    lipoprotein is going to have my
  • 00:23:09
    cholesterol ester in it so again what is
  • 00:23:11
    this molecule here called this is a
  • 00:23:13
    cholesterol ester and this a cat enzyme
  • 00:23:19
    is transferring that a co group that 2
  • 00:23:22
    carbon group onto the cholesterol
  • 00:23:24
    molecule so it's acting as a a co
  • 00:23:27
    cholesterol transferase enzyme and then
  • 00:23:30
    after we package this into a protein
  • 00:23:33
    covering so now this is actually going
  • 00:23:34
    to be the actual cholesterol component
  • 00:23:36
    and around that I'm going to have my
  • 00:23:37
    protein component and on the protein
  • 00:23:40
    component I can have specific types of
  • 00:23:41
    April proteins that we'll talk about
  • 00:23:43
    depending upon the type of life of
  • 00:23:45
    protein it is so for example this can be
  • 00:23:48
    one type you know what this one is
  • 00:23:50
    actually then we can actually call this
  • 00:23:51
    one LDL bad cholesterol okay and this
  • 00:23:59
    one is actually very dangerous if it's
  • 00:24:02
    if there's really really high LDL levels
  • 00:24:04
    that's why whenever people have high
  • 00:24:06
    cholesterol mainly LDL you want to give
  • 00:24:08
    them statins or lipitor because if you
  • 00:24:10
    remember that's going to inhibit the
  • 00:24:12
    hmg-coa reductase enzyme so you don't
  • 00:24:14
    make as much cholesterol so you can't
  • 00:24:15
    utilize it in the lipoprotein pathway so
  • 00:24:17
    again what is the small
  • 00:24:18
    you're called it's called a lipo
  • 00:24:21
    proteins so it's very important for
  • 00:24:25
    making lipo proteins which can go and
  • 00:24:26
    get transported to other different
  • 00:24:27
    tissues you know there's another one
  • 00:24:29
    that you can make here there's another
  • 00:24:31
    one it's actually called VLDL we talked
  • 00:24:33
    about that in the triglyceride synthesis
  • 00:24:35
    video the only difference is is that
  • 00:24:38
    instead of having a significant amount
  • 00:24:39
    of cholesterol you also add in
  • 00:24:42
    triglycerides triglycerides are also
  • 00:24:49
    added into the vldls and significant
  • 00:24:51
    amount there's a lot of triglycerides
  • 00:24:53
    and not as much cholesterol esters but
  • 00:24:56
    nonetheless your liver can make vldls
  • 00:24:58
    and LDL s it can also make other
  • 00:25:01
    lipoproteins which you guys are probably
  • 00:25:02
    heard of called HDLs which are going to
  • 00:25:03
    help for being able to pull some of the
  • 00:25:05
    cholesterol off of the vessel walls but
  • 00:25:07
    we'll have an individual video on that
  • 00:25:08
    but again understanding all of this is
  • 00:25:12
    important but understanding the
  • 00:25:13
    significance of why the cholesterol
  • 00:25:15
    metabolism is occurring is more
  • 00:25:16
    important understand that I can use this
  • 00:25:18
    for synthesis pathways incorporating
  • 00:25:20
    into the cell membrane making steroid
  • 00:25:22
    hormones making bile salt and actually
  • 00:25:25
    helping to make lipoproteins for other
  • 00:25:26
    different tissues because if you imagine
  • 00:25:29
    LDL is actually taking and transporting
  • 00:25:32
    some of that cholesterol to like the
  • 00:25:33
    adrenal cortex you know in the adrenal
  • 00:25:35
    cortex they need that cholesterol they
  • 00:25:36
    need that cholesterol to be able to make
  • 00:25:38
    their steroid hormones so it's very
  • 00:25:40
    important that we have that cholesterol
  • 00:25:41
    so taking it to the testes to be able to
  • 00:25:43
    make testosterone and estrogen so
  • 00:25:45
    without that there could actually be
  • 00:25:47
    potential like life-threatening problems
  • 00:25:48
    but too much of it is also pretty bad
  • 00:25:51
    and again knowing that out of this this
  • 00:25:54
    is one of the most important metabolic
  • 00:25:55
    steps in the entire body you know not
  • 00:25:58
    only lipitor isn't actually inhibiting
  • 00:26:00
    this oh and another thing I'm so sorry I
  • 00:26:03
    didn't mention this this step right here
  • 00:26:06
    we need NADPH too in a dp+ if you guys
  • 00:26:14
    remember this was a very very strong
  • 00:26:16
    reducing agent and we need him in this
  • 00:26:20
    step because of his reducing power NADPH
  • 00:26:23
    is utilized in a lot of different
  • 00:26:24
    pathways you know not just in steroid
  • 00:26:27
    synthesis not just in triglyceride
  • 00:26:29
    synthesis but also for nucleotide
  • 00:26:31
    as well and even to train the synthesis
  • 00:26:33
    of neurotransmitters - so NADPH is
  • 00:26:35
    actually utilized in this step but
  • 00:26:37
    remember this is a highly regulated
  • 00:26:38
    enzyme another thing that can actually
  • 00:26:41
    inhibit this guy at this point here is
  • 00:26:44
    also going to be cholesterol cholesterol
  • 00:26:48
    itself can inhibit this HMG co-reductase
  • 00:26:52
    so high amounts of cholesterol can act
  • 00:26:55
    on this hmg-coa reductase and actually
  • 00:26:57
    inhibit the synthesis of himself he does
  • 00:26:59
    it by activating specific proteolytic
  • 00:27:01
    enzymes so he activates proteolytic
  • 00:27:03
    enzymes that will actually help to
  • 00:27:09
    specifically inhibit this hmg-coa
  • 00:27:13
    reductase but like I told you before
  • 00:27:15
    insulin is also extremely important
  • 00:27:18
    because insulin is also going to try to
  • 00:27:21
    stimulate this enzyme activating this
  • 00:27:23
    enzymes for certain types of second
  • 00:27:25
    messenger intra cellular pathways to
  • 00:27:27
    stimulate this enzyme whereas the actual
  • 00:27:31
    guy who tries to oppose insulin is
  • 00:27:33
    glucagon and you guys know that glucagon
  • 00:27:36
    wants to be able to do what - this
  • 00:27:38
    enzyme he wants to inhibit this enzyme
  • 00:27:40
    inhibit the actual synthesis of
  • 00:27:41
    cholesterol use it for making glucose
  • 00:27:44
    use that ASC decoy to make glucose or to
  • 00:27:46
    help to be able to generate ATP instead
  • 00:27:49
    primarily let it make glucose okay so
  • 00:27:52
    very very highly regulated enzyme here
  • 00:27:54
    alright so in this video we covered a
  • 00:27:57
    lot of information I hope it all made
  • 00:27:58
    sense I hope you guys really did enjoy
  • 00:28:00
    it I hope it clicked if it didn't if you
  • 00:28:02
    guys enjoy - hit that like button
  • 00:28:03
    subscribe put a comment down in the
  • 00:28:05
    comment section guys we really look
  • 00:28:07
    forward to hearing from you guys
  • 00:28:08
    alright engineers until next time
Etiquetas
  • Kolesterool
  • Metabolism
  • Ensüümid
  • HMG-CoA reduktaas
  • Steroidhormoonid
  • Sapisoolad
  • Lipoproteiinid
  • Maks
  • Atsetüül-CoA
  • Günekoloon