Dear /sci/ When was the existence of the lipid membrane proven?

Then you havent fucking tried very hard. Phospholipid membranes are extremely well studied, and there are even commercial sites that will ship refine products (functionalized proteins and lipids, cholesterols, etc) to your lab for experiments.

There are literally thousands of published articles that deal with this subject.

>>6912364
OP has posted this many times in the past, it's a mistake to take him seriously.
https://warosu.org/sci/?task=search2&ghost=&search_text=lipid+membrane&search_subject=&search_username=&search_tripcode=&search_email=&search_filename=&search_datefrom=&search_dateto=&search_op=op&search_del=dontcare&search_int=dontcare&search_ord=new&search_capcode=all&search_res=post

>>6912367
Ahh ok thanks. Whats with the shitposting today, we getting raided by /retarded/ ?

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I've posted something like this several times, and I have yet to get a convincing response. 90% of the responses are:
>You're so stupid
>Go read a book
>You must be a troll

Occasionally someone actually provides an intelligent response, but I have yet to see one that was convincing. People have claimed that freeze fracturing and osmium tetroxide prove the existence of the lipid membrane, but I researched each and found that neither of them do.

It just seems like the lipid membrane was suggested, then everyone just assumed it was true and never bothered to verify it. Now everything is interpreted in that context. Meanwhile, evidence that appears to contradict the lipid membrane model (like Gilbert Ling's entire life's work) is just ignored.

So I don't find the lipid membrane model particularly compelling. Responses like "There are literally thousands of published articles that deal with this subject" don't really prove anything. 100 years ago, you could have said the same thing about the luminiferous ether, which turned out to be false.

>>6912809
why is -the lipid membrane- of all things your particular bugbear?

>>6912815
It seems like an important issue. It's the foundation of modern biology.

I fucking hate you and this retarded thread. The lipid membrane model is supported by shitloads of evidence. Maybe look at a fucking picture of a cell you dumbass. That dark outline on the edge wouldbe the membrane. There is no question if it is there since we can physically see a fucking membrane. We know it's made of a lipid bilayer as well. The lipid molecules act as predicted in a fuckton of experiments such as fluorescence recovery after photobleaching. go fuck yourself and read a journal

>When was the existence of the lipid membrane proven?
never, science cannot prove things, only indicate them to a high degree of confidence.

>>6912829
way to be anti-intellectual, moron

i don't agree with OP at all and have argued with him in every thread he's made, but understanding the philosophical bases by which we arrive at our knowledge is critically important for all scientists

just saying "it just is that way" without trying to construct a reasonable answer for people like OP isn't science, it's scientism

>>6912837
I'm not being anti intellectual. This thread has been made multiple times and I have seen very convincing evidence in every thread. I gave a technique and told him to read a journal.

Op is fully aware he/she is being a fucking dumbass. There is nothing philosophical about the question

>>6912829
The dark outline is the dye that accumulates on the edge of the cell. How does that imply the edge of the cell is two layers of phospholipids?

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Oh look, it's this thread again

People will provide legitimate arguments and linked sources over the duration of the next few days and OP will continue to deny any of them as evidence while providing no sound alternative for the makeup of a membrane

We can infer the existence of a thin membrane at the cell's edge by examining high-resolution x-ray crystallography and comparing it to our knowledge of protein chemistry and by using genetic tools.

We can see that many proteins possess structures that form a hydrophobic region on external surfaces of the protein and hydrophilic regions on internal surfaces of the protein. The existence of proteins such as these is not indicated by the association/induction hypothesis.

Part of the association/induction hypothesis is that cellular water is oriented in a polarized multilayer structure rather than a single thin membrane. However, if we use modern genetic and molecular biology tools, we can do things like attach fluorescent proteins to other proteins in a genetic fusion and examine where they go in the cell. If we do this, we can observe that some of those proteins we were previously examining, with the exposed hydrophobic regions, are localized to a single, thin layer at the periphery. We can even start to perform more complicated experiments such as BiFC or FRET microscopy, where protein interactions facilitate fluorescence. Evidence from these experiments can be used to show that some proteins have distinct domains on exclusive sides of the thin layer observed in microscopic assays.

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>>6912867
>We can infer the existence of a thin membrane at the cell's edge by examining high-resolution x-ray crystallography
In a previous thread like this, someone posted this picture of the outside of a cell. What I find interesting is the hexagonal pattern. In the model of the cell that I believe, the cell water should be arranged hexagonally, which agrees with this observation. To what high-resolution x-ray crystallography are you referring?

>We can see that many proteins possess structures that form a hydrophobic region on external surfaces of the protein and hydrophilic regions on internal surfaces of the protein. The existence of proteins such as these is not indicated by the association/induction hypothesis.
The shape of a protein inside a cell may differ from its shape when examined in isolation. Can you give me an example of what you describe?

>However, if we use modern genetic and molecular biology tools, we can do things like attach fluorescent proteins to other proteins in a genetic fusion and examine where they go in the cell.
Can you provide an example of this? Someone did before, in a similar thread. They claimed to show hydrophobic proteins in the cell membrane. When I read the study, the first step involved grinding up the cell into its components and separating them out by solubility. I'm not sure how that demonstrated the location of anything.

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>>6912895
oops I posted the wrong picture. This is what I meant to post; it's the outside of a cell. Notice the hexagonal structure.

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>>6912895
>To what high-resolution x-ray crystallography are you referring?
I wasn't referring to crystallographic examination of membranes.

>Can you provide an example of this?
Sure. Pic related. The top image is an example of a membrane protein genetically fused to GFP. The middle and bottom images are in plant protoplasts - the little ball things inside the cell are chloroplasts.

>The shape of a protein inside a cell may differ from its shape when examined in isolation. Can you give me an example of what you describe?
You're absolutely right, the crystallized structure is not necessarily the in vivo structure. However, that doesn't happen all that often in practice, and if the structure we observed in the crystallized protein is consistent with other lines of evidence, we can conclude that it's likely to be the in vivo conformation. For example: http://www.plosbiology.org/article/info:doi/10.1371/journal.pbio.0000075 If we observe structures of aquaporin, we can note that there are lots of polar and charged residues in the surfaces we believe to be exposed to aqueous surfaces and very few in the surfaces we believe to be exposed to the membrane interior. This observation is consistent with microscopy experiments showing it to be localized to what seems like a thin membrane at the edge of the cell and genetic experiments showing that disrupting aquaporin gene expression disrupts permeability of the cell to water.

>>6912900
Can you post a picture that's not for ants? And a source?

>>6912943
I don't know the source. Someone else posted that in another thread. I saved the thread, but all I have is the thumbnail.

>>6912942
Thank you for providing a genuinely intelligent response. I will look into this and return with a response.

>>6912950
>>6912943
Ah, I looked it up myself. Those pores are not the membrane itself. They're a porous substrate used to create nanodrums of defined shape that they then poke with an AFM probe. You can read about it here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1479081/

It's not the outside of a cell being displayed, it's an artificial system used to study membranes.

>>6912961
Ah, okay. In that case, the guy who originally posted it did not know what he was posting, though I suppose it makes me look bad to blindly repost it.

>>6912950
Also I'd like to suggest that you stop thinking of this in terms of proving one theory or disproving the other. Instead, think of it like this: There are two competing theories, both of which can be used to explain data to some degree. We will never know for sure if any theory is absolutely true; the best we can do is come to a reasonably confident conclusion that a theory might be true.

We have phospholipid bilayer theory and AIH theory. The question you should be asking is not "is there a smoking gun that proves lipid bilayers", but "which theory is most consistent with all the evidence available".

>>6912942
>chloroplasts
Wait, what
What

>>6912976
It's a plant protoplast.

>>6913007
No, why the hell are there chrloplasts in what looks to be an animal cell

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>>6913012
*chloroplasts

>>6913012
That's because it's not an animal cell.

Protoplasts are prepared by cutting leaf tissue into strips and incubating it in an enzyme mixture that dissolves cell wall. The plant cell is released into solution, and you can perform transient expression experiments and protein analyses on an individual cell basis.

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>>6912852
You must be trolling

The head of a single fosfolipid molecule is hydrophylic and the tail is hydrophobic. A single layer wouldn't even be possible. There have to be 2 layers with the hydrophylic parts on the outside (towarda the cell and the ECM) and the hydrophobic parts have to be inbetween.

There isn't even a doubt whether this model is correct or not.

>Also what are transport proteins

>>6913033
Ah. Learn something new everyday.

>>6912866
/thread

>>6912837
denying well-established scientific facts with as only reason 'it ain't sitting well with me', without proposing an alternative, in the light of an abundance of empirical and theoretical reasons to believe said fact, is the toppest of anti-intellectualism, good sir.

>what is Popper

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>>6912942
What you're describing sounds interesting but I'd need to see more to be convinced. How do you know the orientation of the proteins? How do you know which parts are hydrophobic in vivo? I read the study you posted but it was just a review paper.

>>6913045
You must be trolling if you call it a fosfolipid. I am aware of the alleged structure of the alleged lipid membrane. But seeing a picture in which the dye formed two distinct curves does not seem to conclusively prove that the edge of a cell is two layers of phospholipids and the dye is accumulating at their polar heads. In fact, if the dye is polar, then it doesn't tell us anything about the presence of a lipid.

>>6913195
If you want an alternative, here's one: the Association Induction Hypothesis. Though I find it amusing that you're responding with what's essentially an Argument from Ignorance. I asked for the justification for something supposedly well-known. If it's so well-established, it should be easy to prove.

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>>6913225
Have you honestly never heard of cryotem? There are no dyes involved, you take a cell, freeze it almost instantly in liquid nitrogen, shave it with a diamond razor into sections only 100 nanometers thick, pop that shit into an electron microscope, and take fucking pictures.

picture related, the cell membrane.

with biochemistry you can also isolate and confirm the specific types of phospholipids involved. with biophysics, you can do all kinds of awesome interactive stuff, like binding specific phospholipid binding proteins to the surface, which is what i did for my masters.

fuck you and your thread, OP, nobody is that ignorant unless they are brain damaged. ergo you are just full of shit.

>>6913225
Perhaps you're right. Maybe AIH is a sound alternative. But demanding indisputable proof for an empirical hypothesis is unreasonable, and if AIH truly is the better way of understanding a cell, then you should focus on showing the benefits of this approach over the classical one, in stead of coming here and demanding to be convinced of something which most people accept.

Claiming everybody is just following this dumb and false idea while you see it as it is comes over as arrogant, in my opinion.

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>>6913250
moar. here they have identified actual transmembrane proteins in the cell membrane.

eat such a giant bag of dicks, OP.
http://biochem.web.utah.edu/frost/research_nih.html

>>6913250
>Have you honestly never heard of cryotem?
Did you even read the thread?

>>6913225
>How do you know the orientation of the proteins?
There's lots of ways. There's multiple different technologies which can be used to detect protein interactions in vivo. For example, you can use Bimolecular Fluorescence Complementation (BiFC), which involves genetically fusing half of a fluorescent protein to your proteins of interest, such that protein interactions restore the intact protein and create fluorescence. If you use one half of the FP on a known cytoplasmic protein and the other half of the FP on the putative transmembrane protein, you can distinguish the orientation of the protein. There's also technologies that rely on photon transfer between immediately adjacent fluorescent proteins that allow you to infer physical proximity of proteins.

>How do you know which parts are hydrophobic in vivo?
Chemistry. The basic chemistry of amino acids doesn't change when you take proteins from an in vivo context to an in vitro one. Hydrophobic amino acids will be hydrophobic everywhere. Calculations of protein surface chemistry are performed by examining the chemical profile of the amino acid residues which are closest to the surface.

>>6913278
what the fuck are you even on about, did i read the thread?

yes. its full of OP saying nobody has proved the lipid membrane "model", which is utter bullshit. I also noticed that nobody mentioned cryo-tem or posted actual pictures of the membrane, so there you fucking go.

or do you have a problem with proof as well?

>>6913284
>I also noticed that nobody mentioned cryo-tem
if you had actually read the thread you would have seen that OP mentioned freeze fracturing in the fifth post.

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>>6913250
I see that the edge of the cell looks different from the rest of the cell. How do we know that it's a lipid?

>>6913278
>The basic chemistry of amino acids doesn't change when you take proteins from an in vivo context to an in vitro one. Hydrophobic amino acids will be hydrophobic everywhere. Calculations of protein surface chemistry are performed by examining the chemical profile of the amino acid residues which are closest to the surface.
My question is more about protein structure. For example, if a protein curls into a helix, the polar amine and carboxyl groups may bind to each other, hiding them from the outside environment. This would effectively make the protein more hydrophobic.

If the hydrophobicity of a protein is determined by its structure, then you would need to verify the structure to make the argument that hydrophobic regions collect in the lipid membrane.

>>6913297
>the polar amine and carboxyl groups may bind to each other, hiding them from the outside environment. This would effectively make the protein more hydrophobic.
Side chains, not amino/carboxyl groups. The backbone of a protein is inherently hydrophilic and polar; it's the exposed side chains which confer hydrophobicity, and we know the exposed side chains through high resolution structures.

And yes, you're correct, we have to verify that the structures we see in vitro are what happens in vivo - and that is usually done. And like I said earlier, while it's technically possible that you can get a structure which doesn't exist in vivo, it doesn't happen all that often. Usually, what you get when you crystallize is what you see in the cell.

>>6913304
>Usually, what you get when you crystallize is what you see in the cell.
How do you know that?

>>6913297
>you can isolate phospholipids from cells in large numbers

>you can mix them in a testube with water and they spontaneously form membranes

>you can image either artificial membranes or actual cell membranes with cryotem and they are identical

>you can use membrane binding proteins that bind SPECIFICALLY to certain phospholipids to further show that the membrane contains these phospholipids

it goes on and on and on and on... face it, you are a faggot.

>>6913307
Sometimes, the evidence is internal - for example, it's not unheard of for a protein to crystallize with a known ligand binding to a region which has been experimentally demonstrated to be critical for protein function, so you can see right away that the protein is probably in its natural form.

You can also use alternative technologies, such as NMR, to validate the structure.

And finally, you can do a lot of very computationally expensive assessments to verify that the structure you've found is something that makes sense given everything we know about the physics and chemistry of an aqueous environment.

The way it turns out is that we do usually get pretty good structures, although extensive, stringent validation is required before you publish any protein structure.

>>6913324
Anon, you need to try harder. Most of those points are only evidence for phospholipid bilayers if you already assume that phospholipid bilayers exist. What OP is asking for is evidence that points to phospholipid bilayers alone and can't be used to explain other theories regarding cell structure.

>>6913337
you seriously need to try harder yourself if you think that argument is true.

done argueing with retards in this thread, enjoy the basement.

>>6913348
What argument? Read the thread, I'm arguing for bilayers.

I just think you need to choose your arguments better.

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>>6913324
Can you show me an experiment that demonstrates this?

>>6913327
That sounds reasonable. Do you know of an experiment that clearly shows hydrophobic sections of proteins collecting in the lipid membrane?

This almost sounds like a reversal of the original model. Originally, the lipid membrane was invoked to explain polar substances being excluded from cells and fatty substances entering easily. But you're describing the polar portion entering the cell and the fatty portion being stuck in the membrane.

Also, on the topic of NMR, that technology was invented by a guy who believed in the Association Induction Hypothesis. Clearly, that does not validate the model, but it's interesting.

>>6913337
>most of those points

Do you even read what you post before you hit enter? Anon listed very strong evidence, both direct and indirect, for the existence of phospholipid bilayer membranes in cells. The onus at this point is on OP to both a) successfully refute the evidence and b) provide a reasonable alternative theory.

So far he has failed to do either.

>>6913367
>Anon listed very strong evidence
he did not provide evidence. He asserted the existence of evidence. Providing evidence would mean posting a link to an experiment.

>provide a reasonable alternative theory
In my original post, I simply asked when the lipid membrane was first validated. That seems like a fair question. But now, apparently, it's my responsibility to provide a better model. Why? Do you believe the lipid membrane model because you can't think of a better model? That's called the Argument from Ignorance. Also, if you want another model, look up the Association Induction Hypothesis.

>>6912852

There is no dye in an electron micrograph.

>>6913406
Okay, but how do you know the phenomenon you see on the edge of a cell is a phospholipid bilayer?

>>6913364

>can you show me an experiment that demonstrates this?

http://www.youtube.com/watch?v=I-Y78ARn0Ys

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1302330/

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>>6913417

http://blanco.biomol.uci.edu/bilayer_struc.html

>>6913364
>But you're describing the polar portion entering the cell and the fatty portion being stuck in the membrane.
No, you're not interpreting my post correctly. I'm not talking about proteins moving in and out of a cell, I'm talking about proteins embedded within the membrane.

What you're talking about - polar molecules being excluded from a cell - has to do with transport across the cell membrane. I'm talking about the composition of things inside the membrane.

>>6913367
Yes, I read what I posted.

>Anon listed very strong evidence, both direct and indirect, for the existence of phospholipid bilayer membranes in cells.
Not really.

>you can isolate phospholipids from cells in large numbers
okay, there's phospholipids in the cell - it's only without our current knowledge regarding membranes that we know this fact is relevant to membrane composition. with the same line of reasoning we could say that the membrane is composed of proteins or nucleic acids.

>you can use membrane binding proteins that bind SPECIFICALLY to certain phospholipids to further show that the membrane contains these phospholipids
this is not incompatible with alternative theories. working under AIH, we could propose that the same phospholipids observed as a component of cells are uniformly distributed throughout the cell interior, and what you are observing in this

In order to convince OP of bilayer theory, we need to present evidence that points to bilayers alone, not to both bilayers and AIH. In order to do this, we must carefully consider AIH and the information gained from our experiments.

>>6913425
The second link is not an experiment; it is people making a prediction based on a model.

The first link shows what appears to be a cell splitting into pieces. How does this show a phospholipid bilayer? Any reasonable model of a cell should include the ability of a cell to divide.

>>6913544
Sorry to misinterpret you then. Do you know of an experiment that clearly demonstrates proteins in the membrane, such that the hydrophobic portion is in the lipid region?

>>6913449
That's a paper stating what the author believes; it's not an experiment demonstrating it

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>>6913579
>Do you know of an experiment that clearly demonstrates proteins in the membrane, such that the hydrophobic portion is in the lipid region?
We can perform experiments which demonstrate that proteins are located in the region where we think the membrane is located, and we can perform experiments where we remove the genetic sequence which encodes the regions we think are embedded in the membrane and demonstrate that the protein now permeates the cytoplasm rather than stays bound to the membrane.

>>6913639
Can you give me an example?

>>6913557
>samefagging OP

>>6913666
Nope.

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>>6913579

>The first link shows what appears to be a cell splitting into pieces. How does this show a phospholipid bilayer?

Because they made it out of lipids and you can physically see the bilayer.

>it's not an experiment demonstrating it

Yes it is. Take another look at that picture. They used x-ray and neutron diffraction to determine relative locations of the various parts of the lipids.

>>6912809
We already settled this in the last thread. Various methods of lipid bilayer characterization all show direct evidence of the lipid membrane, including clear pictures showing the bilayer with lipid-specific dyes. Ling fails to explain how all of these methods are giving false positives, and his own model predicts completely different results.

>>6913609
x-ray diffraction is not an opinion.

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>>6913662
Here's one. http://www.ncbi.nlm.nih.gov/pubmed/12034898

In this paper, the authors describe experiments where they fucked around with the transmembrane domain and observed changes in cellular localization.

>>6913689
>lipid-specific dyes
Are you referring to osmium tetroxide? Because I looked into that and it definitely does not prove the existence of a lipid membrane.

>>6913676
They're not describing an experiment; they're describing the conclusions they drew, based on an experiment.

>>6913707
>Are you referring to osmium tetroxide? Because I looked into that and it definitely does not prove the existence of a lipid membrane.
Oh wow. You looked into it. That's just great. Too bad it does. If Ling was correct then osmium tetroxide should should pass through the membrane. What is it binding to?

>>6913707

>They're not describing an experiment; they're describing the conclusions they drew, based on an experiment.

Multiple experiments, actually. Check the bottom of the page. Citation 8 is the complete synthesis of all their data. And unless you can falsify or refute that x-ray diffraction data, all you can say at this point is "nuh-uh".

>>6913676
Also, the video you posted does not appear to be a video of a cell. And they just described it as "mixed lipids." Did they say somewhere that they used phospholipids? Did they demonstrate that the phospholipids collected on the edge of these droplets?

>>6913715
Osmium tetroxide is a strong oxidant and a Lewis acid. In the model I believe, cell water is a Lewis base. So it makes perfect sense that osmium tetroxide would bond to it.

Also, the original claim was that osmium tetroxide only binds to lipids and that its presence indicates the presence of a lipid. So I asked why osmium tetroxide forms two curves, instead of one. The response was that osmium tetroxide oxidizes, forming a polar compound, which diffuses into the region with the polar heads of the phospholipids.

Thus the original claim is invalid. Osmium tetroxide is supposed to indicate lipids, yet it is admitted to form something polar. It is admitted to diffuse into the region with the polar heads of the phospholipids. How does that imply that it interacted with a lipid membrane? All we see is polar activity. It forms something polar, it allegedly bonds to polar heads of phospholipids, and we're supposed to assume that it was previously a lipid and interacted with lipids before this happened.

Meanwhile, it's a Lewis acid, which is not a lipid.

What's your suggested alternative and why would it be better?

Are you also implying that all of biology is wrong in their conlcusions and that in vivo experiments are all wrong or would you just like to change a name and nothing else?

If it's the latter I suggest you change the flow of electrons instead because it really is "wrong" thanks to guesswork predating the experiments.

>>6913733
I've seen your threads before, and it usually seems like you won't take anything as evidence for the existence of lipid membranes. What, short of shrinking you down to the size of Osmosis Jones and showing you a physical lipid membrane would convince you of their existence?

>>6913733
That doesn't make sense. If Osmium tetroxide binded water molecules you would see it accumulating everywhere there's water, not just in on the bilayer.

>>6913748
A suggested alternative would be the Association Induction Hypothesis.

>>6913776
Water is not a Lewis base; hydroxide is. In the model I believe, cell water has excess hydroxides.

>>6913733
>Thus the original claim is invalid. Osmium tetroxide is supposed to indicate lipids, yet it is admitted to form something polar. It is admitted to diffuse into the region with the polar heads of the phospholipids. How does that imply that it interacted with a lipid membrane?
The phospholipid heads are polar you idiot. That's why osmium tetroxide only binds to the inside and outside of the bilayer. You are repeating the argument as if it's an argument against osmium tetroxide binding phospholipids.

>>6913788
>The phospholipid heads are polar you idiot. That's why osmium tetroxide only binds to the inside and outside of the bilayer.
Yes. The inside and outside of the bilayer, which is polar. Not a lipid. Osmium tetroxide was initially mentioned because it supposedly indicated the presence of lipids. If you're admitting that it binds to polar substances, then it does not indicate the presence of lipids.

You can't have both of these statements:
>Osmium tetroxide binds to lipids and its presence indicates the presence of lipids
>Osmium tetroxide binds to polar substances and its presence indicates the presence of polar substances.

>>6913785
>Water is not a Lewis base; hydroxide is. In the model I believe, cell water has excess hydroxides.
Yes, that's what I said. hydroxides are everywhere in aqueous solution. Now you are simply arguing that water is acting exactly like the lipid bilayer. Except we would see lots of behavior we don't see if the membrane was made of hydroxides. For example, we would see Sodium reacting with these hydroxides and accumulating around the cell. That is not what happens at all.

>>6913794
>Yes. The inside and outside of the bilayer, which is polar. Not a lipid.
You said yourself the phospholipid head IS polar. Which is it?

>>6913733

>Also, the video you posted does not appear to be a video of a cell. And they just described it as "mixed lipids." Did they say somewhere that they used phospholipids?

What difference does it make? It's a liposome and all amphiphilic molecules behave relatively similarly.

>Did they demonstrate that the phospholipids collected on the edge of these droplets?

Do you have any idea what refraction is? Why else would the edge of the droplets show two well defined concentric circles if the whole thing
was homogenous?

>>6913794
Osmium tetroxide doesn't bind to all polar substances. Now you are just equivocating by making vague characterizations of my argument. Osmium tetroxide is specifically known to bind to lipid bilayers in the way it does to the cell membrane. It doesn't bind that way to aqueous solution. That's why it's used to characterize bilayers. IT would be extremely stupid to use a dye for characterization when the dye isn't specific. So you are essentially arguing that every single methodology is plagued by amateurish mistakes. Except the only reasoning you have to make this claim is that it is necessary to believe your pet theory.

>>6913794

Osmium tetroxide wouldn't selectively bind in concentric circles if there weren't lipids. What would it be binding to otherwise that wasn't also distributed inside?

>>6913794

>which is polar. Not a lipid.
Your argument is based on ignorance.

>Amphiphile (from the Greek αμφις, amphis: both and φιλíα, philia: love, friendship) is a term describing a chemical compound possessing both hydrophilic (water-loving, polar) and lipophilic (fat-loving) properties. Such a compound is called amphiphilic or amphipathic. This forms the basis for a number of areas of research in chemistry and biochemistry, notably that of lipid polymorphism. Organic compounds containing hydrophilic groups at both ends of a prolate molecule are called bolaamphiphilic. Common amphiphilic substances are soaps, detergents and lipoproteins.

>http://en.wikipedia.org/wiki/Amphiphile

>Phospholipids have amphipathic character.

How about you get some rudimentary knowledge of the subject in general before you create a 100+ post shitstorm over it?

>>6913800
Sodium has a hydration shell which would make it difficult to penetrate the water structure.

>>6913804
Wtf? I get the impression you have no idea what I'm saying. You act as if I've contradicted myself.
>You said yourself the phospholipid head IS polar.
Yes, that is what I said.
>Which is it?
It's polar. That's what I just said. I don't believe in a cellular phospholipid bilayer, but phospholipids have polar heads. I'm not sure how to make this clearer, but I'll restate it:

When osmium tetroxide was first mentioned, it was proposed as a refutation of my claims, because it was called a lipid and thus should diffuse into a cell like other lipids.

But it is not a lipid and does not act like a lipid. If you admit that it bonds with phospholipid heads, then you admit that it does not act like a lipid. So the entire reason it was invoked is invalid.

Is that clearer?

>>6913817
no one has ever claimed that osmium tetroxide is or acts like a lipid. if that's what you inferred, you did so erroneously.

>>6913817
>I don't believe in a cellular phospholipid bilayer.
I don't believe in your brain existing. It seems my camp have more proof than yours.

>>6913821
>no one has ever claimed that osmium tetroxide is or acts like a lipid. if that's what you inferred, you did so erroneously.
Here is a quote from someone else in this thread:
>>6913689
>Various methods of lipid bilayer characterization all show direct evidence of the lipid membrane, including clear pictures showing the bilayer with lipid-specific dyes.

Here is a quote from a previous thread, in which osmium tetroxide was first introduced:
>So how does osmium tetroxide, a lipid stain,...

Perhaps you disagree with the claim that osmium tetroxide only stains lipids, but that is what they had claimed.

>>6913817
>Sodium has a hydration shell which would make it difficult to penetrate the water structure.
Exactly. Why don't we see sodium accumulating around the outside of the cell? How does sodium get into the cell?

>Wtf? I get the impression you have no idea what I'm saying. You act as if I've contradicted myself.
You said it right here >>6913733
>it allegedly bonds to polar heads of phospholipids

>Perhaps you disagree with the claim that osmium tetroxide only stains lipids, but that is what they had claimed.
It only binds to lipid bilayers in the manner it binds to the cell membrane. That is why it is used as a lipid dye.

>>6913828

It interacts with and associates strongly with lipids. That doesn't mean it *acts like* a lipid. Lipids are amphiphilic. Osmium tetroxide is completely non-polar.

>>6913828
you're not showing me anything that says that anyone besides yourself claimed that osmium tetroxide acts like a lipid or is itself a lipid.

people said that it is a dye which preferentially bonds to phospholipids. that is true. that does not mean it is a lipid.

>>6913832
You've got to be trolling. Yes, I did say:
>it allegedly bonds to polar heads of phospholipids
This would only be a contradiction if I also said the opposite of this. Where did I claim the opposite?

>>6913838
Okay, here are more quotes from a previous thread:
>OSMIUM TETROXIDE BITCH, NONPOLAR YET BINDS TO THE CELL MEMBRANE
>NONPOLAR

>But Osmium tetroxide is non polar.

>Osmium tetroxide is nonpolar.

>>6913843
Here you said the bilayer is not a lipid because it's polar:
>Yes. The inside and outside of the bilayer, which is polar. Not a lipid.
So which is it?

>>6913785
>Association Induction Hypothesis
I briefly skimmed the wikipedia article.

And sorry to say but if you believe in this bullshit in the molecular biology era of the year of the lord 2014 then you're obviously weaned on it and have never bothered to learn anything about modern real biology.

Magic water and perpeetum mobile ion diffusion, sound likely. Not.

>>6913843
It binds to the cell membrane because the interior of the cell membrane is nonpolar. It then oxidizes into a charged form which preferentially interacts with the polar head region of the phospholipid.

Nothing is inconsistent here.

>>6913843
You "reasoned" right here that because the lipid bilayer is polar it can't be a lipid:>>6913794
>Yes. The inside and outside of the bilayer, which is polar. Not a lipid. Osmium tetroxide was initially mentioned because it supposedly indicated the presence of lipids. If you're admitting that it binds to polar substances, then it does not indicate the presence of lipids.

>>6913845
WHAT THE FUCK? PHOSPHOLIPID HEADS ARE POLAR. THE TAILS ARE NOT. I NEVER CLAIMED OTHERWISE.

>>6913851
See >>6913850

>>6913855
Okay, I see what happened. You misinterpreted me, but I see why. I said:
>The inside and outside of the bilayer, which is polar. Not a lipid.
What I meant was:
>The inside of the bilayer, i.e. the polar heads of phospholipids, which are allegedly next to the cytoplasm, are polar.
>The outside of the bilayer, i.e. the polar heads of phospholipids, which are allegedly next to the extracellular space, are polar.
>The middle of the bilayer, i.e. the hydrocarbon tails of phospholipids, is non polar.

When I said "inside" and "outside," I was referring to the parts "inside" and "outside" the cell. I see now it was ambiguous.

Anyway, to get back on track, if osmium tetroxide bonds to polar things, then that doesn't tell us anything about a lipid membrane. It just tells us the edge of a cell is polar.

If osmium tetrode is a Lewis acid and the cytoplasm is a Lewis base, then it's consistent with the model I believe.

>>6913755
>Osmosis Jones
kek

>>6913879
>It just tells us the edge of a cell is polar.
it tells us more than that. if that was all it was telling us we'd see uniform staining throughout the cell. we don't see that, which means that somehow the osmium tetroxide is being concentrated in one location before it's oxidized. that is consistent with the lipid bilayer model

>>6913888
>if that was all it was telling us we'd see uniform staining throughout the cell.
Why would we see that? Polar substances are usually excluded from cells, not distributed evenly among them

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I've seen this thread a few times now, and never has anyone actually posted unambiguous, objective experimental evidence for lipid membranes. I'm starting to lean over to OPs side now.

>>6913892
water is a polar substance

>>6912837
Maybe he's just tired of having to read posts made by morons. After 6 years of browsing 4chan I don't even try to argue anymore, it's no use to spell it out to the uneducated, clueless ignorants since they are on a completely different level.

>>6913901
>Maybe he's just tired of having to read posts made by morons.
Then he should just not post.

>>6913899
Yeah, and it's the water that excludes the other substances.

The exclusion of polar substances from cells was the original reason a lipid membrane was invented.

>>6913904
>water that excludes the other substances

>water, aka "the universal solvent"

explain

>>6913917
You can watch it in real time:
https://www.youtube.com/watch?v=i-T7tCMUDXU

If you're impatient, skip to about 5:40. Structured water excludes other solutes.

>>6913935
I'll give you that, but it appears to be a function of the hydrophilic substance attracting water to the exclusion of other substances rather than the water alone.

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OH LOOK ITS THIS RETARD AGAIN

10/10 MAKING ME POST

>>6913935
>tedx
top kek

https://www.youtube.com/watch?v=zhBymLCRIU8

>>6914007
Yes, and intracellular proteins can do the same thing. In the model I believe, the structured water excludes polar substances. No lipid membrane needed.

>>6913935
that was particles in the video, not solutes.

he says "solutes... particles, whatever" with no demonstration of the former claim, and he says it in such a way that he may just be correcting himself and not claiming the exclusion of solutes.

also it's TEDx

>>6914054
Solutes and particles are excluded. You can read more about this; the guy has published plenty of papers. I just posted the video because it's easier to watch. Here's a paper by him:
http://faculty.washington.edu/ghp/images/stories/pubPDF/2006-Zheng_Pollack-Solute_exclusion_and_potential_distribution.pdf

Note the title:
>Solute exclusion and potential distribution near hydrophilic surfaces

>>6913904

The AIH states that layering of water begins at the proteins and extends outward to some apparent limit of 5-7 layers. If the water is stacked H down at some places and O down at other places, how would there be a distinctly visible, organized bilayer like in pictures such as >>6913676 ?

Also, we know of the existence of exosomes and vesicles. We know that the proteins that mediate these and how they interact with lipids. We know that certain knockouts eliminate cells' ability to undergo cytokinesis and other processes that use proteins that are known to interact with lipids. Phospholipase C ring any bells?

A while back you said:

>I see that the edge of the cell looks different from the rest of the cell. How do we know that it's a lipid?

You went on later to talk about OsO4, which you claimed can accumulate in a double layered sphere due to the geometry of the water there (I've yet to see you explain how a hydration sphere could double up and flip polarity to form a double layer. That can't happen with non-amphilic molecules), but what of covalently fluorescently tagged lipids?

http://www.pnas.org/content/96/15/8461/F1.expansion.html

>>6913935
>>6914065
babby's first diffusiophoresis does not disprove cell membranes nor basic laws of chemistry

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>>6914074
>The AIH states that layering of water begins at the proteins and extends outward to some apparent limit of 5-7 layers.
5-7 layers? Where did you get those numbers?

>You went on later to talk about OsO4, which you claimed can accumulate in a double layered sphere due to the geometry of the water there (I've yet to see you explain how a hydration sphere could double up and flip polarity to form a double layer.
If the cell water is charged, that would create an electrical double layer.
http://en.wikipedia.org/wiki/Double_layer_(interfacial)

>but what of covalently fluorescently tagged lipids?
I'll look that up now.

>>6914065
none of this explains the behavior of cells placed in hyper/hypo-tonic solutions

if the cell was a mass of structured water then placing it in solutions of varying salinity should have no effect. we know this not to be the case.

>>6914114
Read the paper by Gerald Pollack:
http://faculty.washington.edu/ghp/images/stories/pubPDF/2006-Zheng_Pollack-Solute_exclusion_and_potential_distribution.pdf

He found that adding solutes to the water decreased the size of the exclusion zone.

If the cell is an exclusion zone, then this is consistent with the shrinking observed when a cell is placed in a hypertonic solution.

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why do people still reply to this guy

>>6914129
So are you proposing that structured water, unlike all other instances of water, is highly compressible?

>>6914137
What? Structured (EZ) water is denser than bulk liquid water, but I don't think its density is especially variable.

>>6914139
Then the cellular volume can't be defined by an exclusion zone around structured water, because the changes in cell volume observed due to changes in salinity are far greater than water at that state can change its density.

>>6914145
The changes in cell volume are due to changes in the number of water molecules. When the exclusion zone shrinks, previously bound water molecules are released.

>>6914103

>5-7 layers? Where did you get those numbers?

Cursory glance at its Wiki. In addition, the solvation shell states

>The hydration layer around a protein has been found to have dynamics distinct from the bulk water to a distance of 1 nm with effects on the surrounding water network extending beyond 2 nm

That isn't large enough to form an organized system of water molecules the size of cells.

>If the cell water is charged, that would create an electrical double layer.

I'll look into this more later. The Walking Dead is on.

>>6914234
I think you read found the reference to 5-7 layers here:
>Parenthetically, by multiple layers, of water this means no more than a few layers (5, 6, or 7 layers of stacked-up water molecules) on each protein chain (and there are a vast number of such protein chains in a typical cell).
That appears to be describing Ling's older model.
>In 2003 Dr. Ling published a new theoretical foundation for the polarized-oriented multilayer theory of cell water[13] that shows that under ideal conditions, a checkerboard of positive and negative sites at the right distance apart can polarize and orient multiple layers of water molecules ad infinitum.
Anyway, Gerald Pollack's work shows that water can be structured far beyond 5-7 layers of molecules.

Also, I read the abstract of the study on covalently fluorescently tagged lipids. The abstract was unclear, but it looked like they were talking about vesicles of cholesterol and phospholipids with nothing polar on the inside. If that's the case, it does not seem like a good model of a cell. If that's not the case, then I really need to read the actual paper because the abstract alone was vague.

>>6914234
Okay I found the full paper. It looks like they used purely lipid vesicles. So it does not seem like a good model of a cell. Also, the whole thing is artificial. The experiment did not study cells; it studied their proposed model of a cell.

If their model is a good model of a cell, then it tells us about cells. But I don't think the experiment proves the validity of the model.

>>6914129

I'm not sure how it took me this long to think of it, but oh well. How does this hypothesis account for aquaporins?

>>6914359
This model does not require aquaporins. Aquaporins were invented to compensate for the lipid membrane, which would otherwise exclude water.

>>6914351

That's beside the point that these tagged lipids have also been used extensively in actual cells, so that ruins your entire argument.

>>6914363

>Aquaporins were invented

lolwut? I'm sorry to break the news to you, b there are aquaporin knockout studies.

>>6914372

but*

>>6914372
>That's beside the point that these tagged lipids have also been used extensively in actual cells, so that ruins your entire argument.
Then show me an example in a real cell.

>lolwut? I'm sorry to break the news to you, b there are aquaporin knockout studies.
Show me an example. If knocking out a gene causes cells to maintain a different level of water, that does not imply that a cell has a phospholipid bilayer embedded with channels through which water can enter. It just means the gene is involved in water regulation.

If you can prove the existence of an aquaporin, please do so.

>>6914377

>aquaporins are a conspiracy!

Jesus Christ. I shouldn't even bother.

>Then show me an example in a real cell

http://link.springer.com/article/10.1186%2F1746-4811-8-28#page-1

>Show me an example

http://www.ncbi.nlm.nih.gov/pubmed/10990371

Too bad we know aquaporin structure and function in extreme detail.

http://www.ks.uiuc.edu/Research/aquaporins/

>>6911604

Are you questioning the existence of phospholipids as the main constituents of the eukaryotic membrane bilayer because you wish to posit an alternate theory of how a cell membrane works?

>>6911604

>What is the flippase enzyme?

>>6914420

Fuck. I though I got him good when I remembered aquaporins. Completely forgot about flippase.

>>6914410
I don't believe cells are surrounded by phospholipid bilayers, because I don't believe cells have lipid membranes.

>>6914402
http://www.ncbi.nlm.nih.gov/pubmed/10990371
All that shows is the gene they knocked out inhibited the rodents' ability to maintain water. You could knockout the gene for vasopressin and get a similar effect. It does not demonstrate that cells are surrounded by a phospholipid bilayer.

http://www.ks.uiuc.edu/Research/aquaporins/
That's not an experiment demonstrating the existence of aquaporins; it's a review article in which an author states their opinion.

>falling for this guy again
/sci/entists when will they learn

>>6914424
>All that shows is the gene they knocked out inhibited the rodents' ability to maintain water.
Oops. That should read:
>All that shows is the gene they knockout out promoted water retention. Knocking out the gene inhibited the rodents' ability to retain water.

>>6914424

How do you explain the existence of phospholipids? How about cholesterol?
How else do you propose a cell exclude its aqueous environment if not with a hydrophobic layer?

>>6914424

>You could knockout the gene for vasopressin and get a similar effect

You know what vasopressin does, right?

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC42627/

See figure 3 of this-

http://ajpcell.physiology.org/content/292/5/C1867

Put 2 and 2 together. We know its structure, its effects, and where it's expressed. We can see it under SEM when we freeze fractionate membranes. Oh, also, explain how freeze fractionation works with just water.

http://www.nature.com/aps/journal/v32/n6/fig_tab/aps201127f1.html

>That's not an experiment demonstrating the existence of aquaporins; it's a review article in which an author states their opinion.

It's a review OF experiments determining the structure and function.

>>6914437
>How do you explain the existence of phospholipids? How about cholesterol?
They exist within a cell. They don't form a membrane.
>How else do you propose a cell exclude its aqueous environment if not with a hydrophobic layer?
See:
>>6913935

>>6914446
>You know what vasopressin does, right?
Vasopressin causes water retention. It's speculated to involve aquaporins, because people believe in aquaporins. What's observable is that vasopressin decreases urination.

>See figure 3 of this-
Those proteins appear to be involved in water regulation. How does that tell us they're small tunnels in a phospholipid bilayer membrane?

>Oh, also, explain how freeze fractionation works with just water.
What do I need to explain? You can freeze water and shave off slices of it.

>>6914457

How does Ling account for the mere existence of phospholipids in cells? What is their purpose, if not for forming the bilayer?

>>6914461
I don't know the purpose of phospholipids.

Nevermind everyone, I figured it out.

I was wrong all along.

Sorry.

>>6914466
Ha. Someone is impersonating me, so I'm using this hash code now. That's annoying.

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>>6914466
cool
nice get

I, like probably the rest of the people on this board, am a little bothered that you don't "believe" in lipid membranes. I'd advise you to look at detergent behaviors, other amphipathic molecules. They group according to phobicity, creating micelles. These behaviors are due to inherent properties of lipids and detergents, have both hydrocarbon ends and polar ends, either alcohols or other charged molecules such as sulfur, in SDS's case. We "know" that the layer is made by lipids because of the ability to isolate and study membranes, and also how their properties make them the only candidate for transmembrane proteins: concentrated hydrophobic residues are within the membrane or trapped in oil droplets inside the cell.

>They exist within a cell. They don't form a membrane.

Again, we can tag those and see where they are.

Figure 3 shows where they are. Add that to the diffraction data that elucidates their structure and how water flows through them from the review link. The combination of all that gives you the structure, location, and mechanism of action.

>What do I need to explain. You can freeze water and shave off slices of it.

Slices of it that can be analyzed and shown to be composed of lipids.

http://www.ncbi.nlm.nih.gov/pubmed/15629118

>>6914486
From your link:
>No membrane-associated particles are observed.

>>6914483
Soap forms bubbles, which are somewhat analogous to a cell. Except bubbles are extremely fragile and the slightest disruption destroys them. Cells are amazingly resilient. I don't deny that lipids can form micelles, but I don't think cells are such an object.

>>6914490

"Membrane particle" means exosome, endosome, vesicle, etc.

http://pharmrev.aspetjournals.org/content/64/3/676.full

>>6914500
Do immunocytochemistry on highly hydrophobic molecules or protein sequences and you'll see your answer, as I mention in my previous post, that they are localized to the membrane or found in lipid droplets. Look at EM pictures, look to characterization of transmembrane receptor proteins and channels that has been done. You'll find even more support.

>>6914514
Okay, let's look at freeze-fracturing more closely. When I looked up freeze fracturing before, I found that later papers all assumed they were seeing the lipid membrane and cited earlier papers as justification. So I read the early, foundational papers that were being cited. Here's one:
http://www.pnas.org/content/55/5/1048.full.pdf

Read the "Discussion" section. The last sentence of the first paragraph. It's essentially saying, "this must be the lipid membrane, because we can't find any other space where it could be." That's not proving the lipid membrane; it's assuming it. Then later papers cite this one and now it's taken as fact.

>>6914525
>Do immunocytochemistry on highly hydrophobic molecules...they are localized to the membrane or found in lipid droplets.
Can you provide an example? People basically said the same thing to me about osmium tetroxide and it turned out to be totally different.

I'm off to bed. I'll check this thread again in the morning.

>>6914528

From that paper:

>20-A thick layers separated by a lighter 35-A thick layer

There's a bit of variance due to different chain lengths, but that fits two layers of lipids pretty well.

As for the sentence you're referring to, I'm not exactly sure what they mean, but it certainly isn't what you're saying it is.

>For similar reasons these confluent ridges cannot be mere eutectic mixtures or organized, but nonmembrane, cytoplasmic components, as this would reduce the dimension of the biological membrane to that of a Euclidean plane.

And how, exactly, does that refute direct analysis of the slices from >>6914488 ?

http://jcb.rupress.org/content/107/6/2511.full.pdf

cheap niggers

>>6914599

Good one

>>6914644

In retrospect, that seems like it could be interpreted as sarcasm. None meant.

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>>6914596
>And how, exactly, does that refute direct analysis of the slices from >>6914488 ?
I don't think your link says what you think it says. It does not talk about a phospholipid bilayer. It just says they found some lipids in a blood cell. We don't even know exactly what they did, because all we have is an abstract (unless you have the full version, which I don't). They even admit that what they're seeing has "undergone considerable rearrangement from the original membrane." So either what they're seeing doesn't match what they expected to see or their methods genuinely disrupted the cell structure. Either way, I don't see any sentences saying "we found a phospholipid bilayer and were able to peel it off and examine it with freeze fracturing." It's more like "we found some lipids. Some of them were different from what we expected."

>For similar reasons these confluent ridges cannot be mere eutectic mixtures or organized, but nonmembrane, cytoplasmic components, as this would reduce the dimension of the biological membrane to that of a Euclidean plane.
The Euclidean plane has no width. Read that whole paragraph. They're trying to justify that what they're seeing is the lipid membrane. They say what they're seeing cannot be non-membrane components, because that would leave no space for a membrane; the membrane would need to be infinitesimally thin to fit. That's what a Euclidean plane is. Infinitesimally thin.

>What we're seeing cannot be non-membrane components because then the membrane would need to be infinitesimally thin to fit!

The other conclusion to draw is that the membrane simply isn't there.

>>6915080

>It just says they found some lipids in a blood cell.

It says they found lipids when they took a thin sheet off the very top of a cell, not from within the cell.

>So either what they're seeing doesn't match what they expected to see or their methods genuinely disrupted the cell structure

That's not at all what they mean by that. They're talking about the normal membrane vs. membrane rafts, not pre-treatment vs. post-treatment.

Also keep in mind that in the old paper what they saw was not affected by etching, a common tool used in freeze-fracturing to remove WATER.

http://www.ncbi.nlm.nih.gov/pubmed/17406618

If they take the very edge of a cell and find lipids and they sublimate ice after they took off what they assumed was the top of the bilayer and see no change, how does that reconcile with your hypothesis?

How do you explain radiolabel studies where cells are given tagged lipid precursors which we can then see accumulate at the edge once they're metabolized?

http://www.jbc.org/content/246/16/5162.full.pdf

>>6915080

Isn't it such a weird coincidence too that freeze fracturing artificial membranes gives similar results as freeze fracturing live ones?

>>6911604
>proven to be false
Citation needed

We have directly observed the phospholipid bilayer

>>6912809
Last time I saw you post this we provided a substantial amount of evidence, disproved your theory, and discredited your sources.

Go home

>>6912852
Because the phospholipid molecules are what the dye is adhering to

>>6915579
>a substantial amount of evidence
Post it again, now I'm curious.

>>6915571
>Citation needed
Do you disagree that sodium can enter cells and potassium can leave cells? This is the reason the sodium/potassium pump was invented.

>>6915579
Why bother proving your point when you can just declare you've already won? It's so simple! If only I'd thought of that!

>>6915598
That's your interpretation of the evidence. The actual evidence is just one or two dark rings around a cell.

>>6915560
Hold on. These responses either come in big waves or not at all.

>>6915571
Behold, sodium can enter cells and potassium can leave cells:
http://jp.physoc.org/content/134/2/278.full.pdf

Observations like these led to the invention of the Na/K ATPase. Which is strange, because a lipid membrane should prevent sodium from entering. This situation would be explained without a lipid membrane, but adding a lipid membrane necessitates the pumps. So rather than abandoning a model that did not match the evidence, they made the model more complicated to compensate. But what does the lipid membrane do? Something that is not observed.

>>6915626
Pure sophistry. Models can and should be changed to account for new data. The fact that something needed to be added to the model does not invalidate the new model. And in fact we have separate evidence of ATPase existing.

>>6915649
Then answer the question in the original post. When was the lipid membrane first proven? What experiment validated it?

>>6915560
>If they take the very edge of a cell and find lipids and they sublimate ice after they took off what they assumed was the top of the bilayer and see no change, how does that reconcile with your hypothesis?
What do you mean?
>they sublimate ice
>see no change
If they see no change, how do they know they anything sublimated?

>That's not at all what they mean by that.
It sounds like we are interpreting their abstract differently. If you can show me the full paper I'll read it, but otherwise it seems like this won't go anywhere if we can't agree on what they mean.

>It says they found lipids when they took a thin sheet off the very top of a cell, not from within the cell.
Lipids usually accumulate on top of water. Anyway, we really need a full paper, rather than trying to interpret an abstract.

>http://www.jbc.org/content/246/16/5162.full.pdf
I'm reading it now.

>>6915615
>>6915674
All evidence needs to be interpreted. So essentially no possible evidence could be provided to you that you would not reject. This is not science, it's religion. Let's look at the many pieces of evidence showing a lipid bilayer and NOT a water membrane:

1. Applying a voltage to a cell and measuring the current shows a high resistance. This is due to the hydrophobic core of the lipid membrane. If the membrane was water we would see a lower resistance.

2. Fluorescence microsocopy with lipid stains shows the structure of the bilayer. And no if the membrane was made of water, these dyes would not adhere to the membrane. They would not be useful as lipid stains if they also adhered to water.

3. Electron microscopy is used on rapidly frozen and dissected cell membranes and shows the lipid bilayer structure.

4. P-NMR spectrosocopy shows the specific spectra of lipids in the membrane.

5. Atomic force microscopy is used to probe the bilayer. This is done without dyes and even through water. The probe does not respond to water in the same way it does lipids.

All of these techniques concur on the lipid bilayer nature of the membrane. It is simply foolish and dogmatic to claim that all of these varied methods are completely wrong and giving the same false positive. The AIH cannot explain these results.

http://link.springer.com/referenceworkentry/10.1007%2F978-3-642-16712-6_564

Scientists know it exists because they took a picture of it, and as pictured does not contradict the current theory

>>6915716
>Applying a voltage to a cell and measuring the current shows a high resistance
Okay
>This is due to the hydrophobic core of the lipid membrane.
That's your interpretation.
>If the membrane was water we would see a lower resistance.
It depends on the state of the water. "EZ" water is charged, as has been demonstrated by Gerald Pollack. Cell water is not liquid bulk water.
>Fluorescence microsocopy with lipid stains shows the structure of the bilayer.
That's your interpretation.
> And no if the membrane was made of water, these dyes would not adhere to the membrane.
I don't think you appreciate the model I'm presenting, because you misrepresent it.

>The AIH cannot explain these results.
Your incorrect impression of the AIH cannot explain these results. If cell water is charged, it creates an electrical double layer.
http://en.wikipedia.org/wiki/Double_layer_(interfacial)
That explains the double-ring image you see.

>>6915721
It takes more than just a picture to prove a model. Explain this:
http://jp.physoc.org/content/280/1/105.full.pdf+html

It directly contradicts the idea of a lipid membrane. In fact, the entire purpose of the experiment was to disprove the lipid membrane, and it appears to do so.

>>6915741
>That's your interpretation.
No, it's the interpretation of scientists whose job is to interpret the evidence. This is not a response to the argument, it's a non sequitur.

>It depends on the state of the water. "EZ" water is charged, as has been demonstrated by Gerald Pollack. Cell water is not liquid bulk water.
That's my point. Charged water would show low resistance. Nonpolar hydrophobic molecules resist electrically charged species, which means high resistance.

>Your incorrect impression of the AIH cannot explain these results. If cell water is charged, it creates an electrical double layer.
http://en.wikipedia.org/wiki/Double_layer_(interfacial)
That explains the double-ring image you see.
It doesn't explain it at all. Lipid stains are not attracted to charged water.

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>>6915626

>invention of the Na/K ATPase

That's weird, considering we've been able to isolate that enzyme and study it on its own.

http://www.ncbi.nlm.nih.gov/pubmed/9416006

4chan doesn't like google's link shortener, apparently. Picture also related

>>6915615

>The actual evidence is just one or two dark rings around a cell.

Dyes like HTMA-PFP behave the same in artificial lipid membranes and in vitro/vivo. We know how they bind to lipids in artificial scenarios, so if you think that lipids are distributed evenly inside cells, why don't these dyes permeate the entire interior? They should if the lipids aren't concentrated in a bilayer on the exterior.

>>6915777
>No, it's the interpretation of scientists whose job is to interpret the evidence.
Appeal to authority.

>That's my point. Charged water would show low resistance. Nonpolar hydrophobic molecules resist electrically charged species, which means high resistance.
Then give me an example of what you mean.

> Lipid stains are not attracted to charged water.
Give me an example. People said the same thing about osmium tetroxide and it turned out to be totally different.

>>6915756
That assumes the cell membrane doesn't spontaneously reform after cutting, which we already know lipid membranes. It's pretty silly that Ling doesn't even consider such an obvious possibility. But then again it's understandable given that he is trying to prove his own pet theory.

>>6915791
>That assumes the cell membrane doesn't spontaneously reform after cutting, which we already know lipid membranes
First, this does not seem realistic, based on experience. A punctured bubble pops; it does not reform. If a lipid membrane were punctured, one would expect the hydrophobic portions to congregate, rather than to push through the water to re-connect.

Anyway, someone made the same argument before and posted an experiment that supposedly showed the "spontaneous reforming" of the lipid membrane. That's not what it showed.

In the experiment, they punctured the cell and measured the amount of calcium that leaked in. Because very little calcium leaked in, they took that as evidence that the lipid membrane reformed. I don't believe in a lipid membrane and structured water has already been demonstrated to exclude solutes, so their interpretation is not the only one.

This is what I see every time. Someone conducts an experiment and they interpret the results under the assumption that the lipid membrane exists. Then they present this experiment to me and say "See? This demonstrates the lipid membrane!" No. You interpreted it in a way that involves a lipid membrane.

Can you show me an experiment in which the lipid membrane definitely reforms?

>>6915790
>Appeal to authority.
As opposed to your appeal to... yourself? An appeal to authority is better than no argument at all.

>Then give me an example of what you mean.
Resistance represents the ability of some material to resist electrical current. For example, deionized water (as little charge as possible) has a conductivity of 5.5 μS/m while sea water (lots of charged ions) has a conductivity of 5 S/m.

>>6915560
Also, I read most of your study:
http://www.jbc.org/content/246/16/5162.full.pdf

I don't think it shows what you think it shows. They "ruptured" cells and collected what was left over. They assumed this was only the membrane, because they assumed that the rest of the cell would leak out without a membrane to hold it together. That's their assumption.

Then they showed these "membranes" incorporated the various tagged substances, like fucose (a sugar). You call these lipid precursors. I admit fucose, as a sugar, can be a lipid precursor. Sugars can be converted into fat via de novo lipogenesis. But this study gave no indication that this had happened. They just found fucose in the "membranes."

So really what happened is they punctured cells, exposed them to fucose, and found fucose in whatever was left in the cells. If cells have no membrane and the cytoplasm sticks together all on its own, then the cell would still be somewhat intact after the rupturing. So it's not surprise that it absorbed some sugar.

I don't see how this proves a lipid membrane. And why would a lipid membrane take up sugar?

>that one guy that insists on pointing out which porn stars will sleep with asians
>that one guy that doesn't think lipid membranes be like it is
what are some other nutters here bros

>>6915808
I asked for an example, not a definition of resistance. Show me an example of resistance across a cell membrane.

>>6915789
>Dyes like HTMA-PFP behave the same in artificial lipid membranes and in vitro/vivo. We know how they bind to lipids in artificial scenarios
Show me an example. People basically said the same thing to me about osmium tetroxide and it turned out to be totally different.

>>6915790
http://en.wikipedia.org/wiki/Nile_red

Nile red is attracted to and fluoresces in lipids, but not in aqueous solution.

>>6915802
>First, this does not seem realistic, based on experience. A punctured bubble pops; it does not reform.
A bubble of fat surrounded by water will close itself instantly after being cut. This is basic lipid behavior and the basis for vacuole formation.

>In the experiment, they punctured the cell and measured the amount of calcium that leaked in. Because very little calcium leaked in, they took that as evidence that the lipid membrane reformed. I don't believe in a lipid membrane and structured water has already been demonstrated to exclude solutes, so their interpretation is not the only one.
https://www.youtube.com/watch?v=KPtsEmfFrNI#t=23

>>6915819
http://www.pnas.org/content/69/12/3561.full.pdf
http://www.bme.umich.edu/labs/biomembrane/publications/papers/insulating_tethered_lipid_bilayers.pdf
There are several more, google it yourself.

>>6915834
Show an example of evidence for AIH. You've been given several pieces of evidence. All you've done so far is either ignore them or call them interpretations. Both are unresponsive.

You have not explained why charged water would have a high resistance. You have not explained why charged water would be detected by forced microscopy. You have not explained why freeze fracturing and dissecting the membrane shows lipid molecules. You have not explained how every lipophilic stain is being fooled by charged water. You have not explained why P-NMR of the membrane shows lipid spectra. All you have is a single piece of circumstantial evidence from the slicing of a frog cell which isn't even frozen, based on the assumption that lipid membranes don't reform, which is false. You have nothing. You failed. If we give a minute fraction of the level of skeptical scrutiny you have given to the lipid bilayer theory to your own hypothesis, it fails immediately.

>>6912867
>Part of the association/induction hypothesis is that cellular water is oriented in a polarized multilayer structure rather than a single thin membrane.

Are there even any explicit solvent computational simulations that are routinely done with complex proteins to back this purported "structured water" phenomena, using known laws of physics? Does it produce any meaningful (aka testable and falsifiable) difference from the membrane models? To be science, you must be testable and falsifiable.

>>6915818
>what are some other nutters here bros

>IQ threads
>Troll threads
>closet dualists
Most of this place is terrible.

>>6915834

I just went back and followed that whole osmium tetroxide exchange toward the beginning. You said that-

1. Cell water has excess hydroxides
2.Osmium tetroxide selectively binds to hydroxides

If hydroxides are all over inside cells, why would the tetroxide be concentrated at the outside?

Going back to a link I posted yesterday that you didn't address.-

http://link.springer.com/article/10.1186%2F1746-4811-8-28#page-1

Fluorescent lipid analogues concentrated where the membrane would be. Lipids of all varieties strongly associate with each other in aqueous solutions. If the interior of the cell were homogeneously inhabited by lipids, the fluorescent ones would not be limited to the outside.

What would these lipid analogues have a higher binding affinity with in vivo?

>>6915809

>But this study gave no indication that this had happened. They just found fucose in the "membranes."

Is that a common occurrence? Why would unincorporated fructose do that?

>And why would a lipid membrane take up sugar?

If you're denying the existence of glycolipids on the surface of cells, then you have a whole other can of worms trying to explain cell self-identification.

>>6915874
Originally, I asked for evidence for the lipid membrane. Your response is now to ask me for evidence for the model I believe. I'd still like to know what I originally asked, i.e. when was the lipid membrane first proven? Which experiments verified it?

>Show an example of evidence for AIH
Gerald Pollack's work was posted earlier in this thread. He has demonstrated that hydrophilic surfaces structure water in a way that excludes solutes. That is the basis of AIH. You can see it happen in real time. Solutes are excluded, no lipid membrane necessary.

Here's more evidence for the AIH:
http://jp.physoc.org/content/280/1/105.short

Among the alkaline metals, the ion with the highest atomic number is accumulated, while all others are excluded. This contradicts the lipid membrane model, in which the Na/K ATPase always pumps potassium in. Also, to be consistent with the lipid membrane model, accumulation of rubidium would require a rubidium pump. Yet somehow, this pump also reverses in the presence of cesium.

>You've been given several pieces of evidence. All you've done so far is either ignore them or call them interpretations.
They are interpretations. When we see two dark rings around a cell, that's an observation. When we say it's because the dye is binding to phospholipid heads, that's an interpretation. It's not directly evident. It's the lipid-membrane-model's explanation of the evidence.

>You have not explained why freeze fracturing and dissecting the membrane shows lipid molecules
I don't think it does. This was discussed earlier:
>>6914528

Freeze fracturing shows something, and it was assumed to be the lipid membrane, because that was the only way to interpret it consistent with the existence of the lipid membrane.

>You have not explained how every lipophilic stain is being fooled by charged water.
People said osmium tetroxide is a lipid stain and that turned out to be totally wrong. That was also discussed earlier in this thread.

>>6911604
This is the worst of all the periodic threads on /sci/

Surely you can find some new gimmick to troll /sci/ and feel important each week.

>>6915925
>http://link.springer.com/article/10.1186%2F1746-4811-8-28#page-1
That's just a review article. Show me an experiment and I'll give you my response.

>Is that a common occurrence? Why would unincorporated fructose do that?
I see you did not read your own study. They used fucose, NOT fructose. Read your study.

If the lipid membrane takes up fucose, a polar molecule, then that gives no indication of the membrane being a lipid. Here is an alternative explanation of what was observed:

A cell was punctured. This did not destroy it. Then it was exposed to fucose (not fructose). It absorbed some fucose. The end.

You previously called fucose a "lipid precursor." How is that even relevant? A cell took up fucose, a sugar.

>If hydroxides are all over inside cells, why would the tetroxide be concentrated at the outside?
This was already covered. Structured water excludes solutes:
>>6913935

>>6915931
>Originally, I asked for evidence for the lipid membrane.
I gave you plenty of evidence, you just ignore it by calling it "interpretation".

>Among the alkaline metals, the ion with the highest atomic number is accumulated, while all others are excluded. This contradicts the lipid membrane model, in which the Na/K ATPase always pumps potassium in. Also, to be consistent with the lipid membrane model, accumulation of rubidium would require a rubidium pump. Yet somehow, this pump also reverses in the presence of cesium.
Rubidium has been known to be an analogue for potassium for some time, so no, no rubidium pump is necessary. http://www.ncbi.nlm.nih.gov/pubmed/3520625

>They are interpretations. When we see two dark rings around a cell, that's an observation. When we say it's because the dye is binding to phospholipid heads, that's an interpretation. It's not directly evident. It's the lipid-membrane-model's explanation of the evidence.
It's an interpretation based on what we know about the dye. Your hypothesis is also an interpretation, and one that doesn't explain why the lipid dye is suddenly attracted to charged aqueous solution. All evidence is interpreted observation so pointing this out is irrelevant. The question is which interpretation makes more sense.

>Freeze fracturing shows something, and it was assumed to be the lipid membrane, because that was the only way to interpret it consistent with the existence of the lipid membrane.
Just more sophistry. If someone gave us a picture showing the individual lipid molecules you would just call this "an interpretation assuming that we are seeing lipid molecules because they must be there". In fact the paper given goes through several descriptions and examples showing that the membrane is consistent with lipid vacuoles, not "it must be the lipid".

>>6915931
>People said osmium tetroxide is a lipid stain and that turned out to be totally wrong.
No, it's completely correct that osmium tetroxide is a lipid stain. Your equivocating did nothing to refute that. It was and continues to be used to characterize lipids.

>>6916028
Seconded here, you can replace up to 50% of a rats diet of potassium with rubidium and they'll be just fine.

>>6916028
>Rubidium has been known to be an analogue for potassium for some time, so no, no rubidium pump is necessary.
If rubidium is an analogue for potassium, then why does the presence of rubidium cause potassium to be pumped out? If the two are interchangeable, then both should be pumped in.

>>6916031
>No, it's completely correct that osmium tetroxide is a lipid stain.
It's a Lewis acid. That means it bonds to Lewis bases, not lipids. It doesn't even stain tripalmitin.

This is the standard explanation for osmium tetroxide:
It diffuses into the lipid membrane, reacts with the double bonds in hydrocarbon chain, forms polar compounds, and diffuses out to bond with the phospholipid heads.

But we don't see all of that. All we see is two dark rings. Supposedly, those are the phospholipid heads. But the two dark rings give us no indication that the osmium tetroxide originally stained a non polar hydrocarbon; that's just postulated. All we see is the end product.

Two dark rings are also explained by the electrical double layer:
http://en.wikipedia.org/wiki/Double_layer_(interfacial)

>>6916031
Behold: osmium tetroxide stains gelatin!
http://jhc.sagepub.com/content/16/3/157.short

Gelatin is an analogue of the model of the cell I believe, so this is completely consistent with my model.

If osmium tetroxide only stains lipids, why does it stain gelatin and not tripalmitin?

>>6915931

>When we say it's because the dye is binding to phospholipid heads, that's an interpretation

It's based on model studies using artificial membranes. If the dye selectively binds to lipids (demonstrated in the models), why wouldn't it bind to the lipids in the cells? If structured water excludes solutes, how would these dyes make their way to both sides of the interface to form two rings? I watched that video. The exclusion zone was gigantic. If that happened around the supposed double layer, nothing would ever come in close proximity to it.

>I see you did not read your own study. They used fucose, NOT fructose. Read your study

As if my misreading means anything. Now you're just being petty.

>That's just a review article. Show me an experiment and I'll give you my response.

Excuse me? Review articles don't typically include extensively results and methods sections saying "we did blah blah blah". Speaking of not reading...

>You previously called fucose a "lipid precursor." How is that even relevant? A cell took up fucose, a sugar.

And that fucose is demonstrably used to produce glycoproteins.

http://www.ncbi.nlm.nih.gov/pubmed/9686143

Unicorporated fucose wouldn't behave like a protein on a gel.

>>6916062
>why does the presence of rubidium cause potassium to be pumped out?
Where are you getting this information from?

>>6916076

extensive*

Proofreading is overrated.