Wet Monomers shouldn't become polymers - but ...

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Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on June 30th, 2017, 12:14 pm 

Wet monomers shouldn't become polymers - but in living things they do.

To what extent do you agree with this and do you feel that this indicates that life is something special - with the ability to avoid normal chemical processes?
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on June 30th, 2017, 8:17 pm 

It seems like you're starting from a false premise.

Sorry but there is nothing magical about life from a chemical point of view.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 2nd, 2017, 5:05 am 

Hi BioWizard.

I got this prominent and eye-catching quote from another website.

It is a bold claim but one I wasn't able to seriously challenge as I am not a chemist.

Your response was very generic, so I couldn't get anything useful from it. Were you just pronouncing that
- because it happened in living bodies it must be normal, or
- were you saying that in the sterile world of chemical reactions there are other examples of wet monomers becoming polymers?

(I don't have a bias on this issue - I just want some substance to support one or other side of the argument).
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 2nd, 2017, 11:39 am 

scientificphilosophe » 02 Jul 2017 04:05 am wrote:I got this prominent and eye-catching quote from another website.


Would it be too much to ask that you share this source with the rest of us?
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 2nd, 2017, 11:45 am 

scientificphilosophe » 02 Jul 2017 04:05 am wrote:Your response was very generic, so I couldn't get anything useful from it. Were you just pronouncing that
- because it happened in living bodies it must be normal, or
- were you saying that in the sterile world of chemical reactions there are other examples of wet monomers becoming polymers?


I apologize if I wasn't clear. Allow me to clarify.

You stated:

scientificphilosophe wrote:Wet monomers shouldn't become polymers - but in living things they do.


I responded that you are starting with a false premise.

Which meant that your starting premise (above) is factually incorrect. Therefore the correct answer is option n#2.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 3rd, 2017, 5:41 pm 

Hi BioWizard

I thought you may ask which website, so I am trying to find it, but the text I copied doesn't mention the website address. I will continue to try to find it.

Re: your answer - fine - now I have two polarised options neither of which elaborate to prove a case - so not helpful.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 3rd, 2017, 7:19 pm 

My own confusions with the original statement are these:

1. I do not know what is meant exactly by a wet monomer.
2. It is well known that most natural polymers form through a dehydration reaction, but I didn't think this meant that the original monomer had a spare water molecule attached. I thought it meant that the reaction between hydrogen atoms on one molecule plus an oxygen atom on another would allow a new water molecule to be released from the combined monomers.
3. The implication from the statement is that natural polymers do not form outside the living cell. Is that true?
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 3rd, 2017, 10:41 pm 

Actually, part of the reason I asked you for the source is because the statement, which appears to be false at face value, can simply be meaningless gibberish. I was hoping I might be able to get a better sense from context.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 4th, 2017, 10:33 am 

BioWizard » July 4th, 2017, 3:41 am wrote:Actually, part of the reason I asked you for the source is because the statement, which appears to be false at face value, can simply be meaningless gibberish. I was hoping I might be able to get a better sense from context.


Yes, I know, but the text was lifted a few years ago.
I always wondered if there was any truth to it.

I hate misinformation, but on this point I couldn't find any clarification.
I have tried again in recent weeks through searches on the web - but nothing I can find seems to specifically address the 3 points above.

Can you help?
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 4th, 2017, 11:02 am 



I believe I already did.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 10th, 2017, 8:04 am 

BioWizard

You made a statement but didn't back it up.
If the non-expert is to decide between two competing pronouncements we need one party or the other to substantiate their position. I was asking for your help in resolving the dilemma.

To simply say that something ... "appears to be false at face value, [or] can simply be meaningless gibberish." doesn't help in this respect because it does nothing to substantiate your view on any of the 3 specifics I mentioned.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 10th, 2017, 8:08 am 

How did I not back it up? I said polymerization routinely occurs in solution phase, including in water. You basically have all of chemistry and biochemistry to look at. This is not secret information and you seem to be able to google. I can post 10-20 references on this later if you wish.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 10th, 2017, 8:13 am 

By the way, if you can't provide more specific definitions of the terms you yourself use, then I can't help you find precise answers. For example, it's not clear whether wet here is used to mean any solution, or whether it is used to mean specifically water. I said the statement is false either way, though, because instances of polymerization occur in both water and other solvents.

In the mean time, if you could provide just one of your sources, whether here or in the other thread, that would be helpful. Maybe we can figure more out from context.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 10th, 2017, 8:21 am 

BioWizard » July 10th, 2017, 1:08 pm wrote:How did I not back it up? I said polymerization routinely occurs in solution phase, including in water.


Where did you say this?

As in other posts, I do value your references, so yes, some would be useful thank you.
Per my other posts, part of my difficulty is that I don't have membership/access to many scientific institutions/websites so your pointers are great.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 10th, 2017, 8:26 am 

Oh, I thought it but didn't write it - because I was still waiting to see your source to make sure that I am understanding the question in the first place.

In any case, there you have it now. If you're satisfied with my interpretation and answer, then sure I'll provide you with references for those.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 11th, 2017, 4:33 am 

As I said before - I'm checking out whether this phrase had any truth in it.

It will really help me to have your sources etc.
Thanks
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 11th, 2017, 5:23 am 

scientificphilosophe » 11 Jul 2017 03:33 am wrote:As I said before - I'm checking out whether this phrase had any truth in it.

It will really help me to have your sources etc.
Thanks


Yes, sure thing. I will collect some for you Saturday or Sunday. There's a lot lf polymerization reactions that we do in routine molecular biology lab work which occur on aqueous phase. I'll list some of those for you too. I may do that sooner of I can find the time, though this week is looking very crammed. Most likely in the weekend.

Were you able to locate the source for your original statement yet?
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Re: Wet Monomers shouldn't become polymers - but ...

Postby wolfhnd on July 11th, 2017, 5:58 am 

It was fairly easy to find the source of the quote. It seems to come from a science critic although critic in this case means more of a humorist than denier. The book is
A Short History of Nearly Everything By Bill Bryson

Here is a list of some of the errors in the book.

http://errata.wikidot.com/0767908171

When googling the quote you will find the excerpt page.

https://books.google.com/books?id=_CWlK ... o.&f=false
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Re: Wet Monomers shouldn't become polymers - but ...

Postby scientificphilosophe on July 12th, 2017, 5:09 am 

Thanks Wolfhnd.
Perhaps I've been looking in the wrong place.

Clearly the statement was a generalisation, but do you feel that there is a grain of truth in it?

I am getting comments from an alternate dialogue, (a person who is a non-bio chemist), that while it is far from an absolute truth, in pure chemical terms an aqueous solution is more likely to break polymer bonds rather than allow them to form... but it depends on which chemicals we are talking about.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 16th, 2017, 11:33 am 

scientificphilosophe, I'm going to try to wrap this one up quickly, because I'm short on time. Though if you find something insufficiently clear, you're welcome to ask. That said, I encourage you to use this post as a road map for learning the basic principles that will allow you personally to reason why the claim is false. You can start with the references I provide and flesh out.

Polymerization is a process where monomeric molecules react to form polymeric chains or three-dimensional networks. There are many forms of polymerization and different systems exist to categorize them.

Whether a polymer would be affected by the presence of water depends entirely on the type of the reactants and the type of bond that ties them together into a polymer.

Here's why...

Polymerization reactions, like any other type of chemical reaction, may be reversible or irreversible. If the reaction is reversible, then we can use Le Chatelier's principle to predict what occurs when you add more reactant or more product. If the polymerization reaction involves the elimination of a water molecule to form a covalent bond between monomers (i.e. Dehydration Polymerization), then adding more water (product) will push the reaction in the reverse direction (break the bond and release the monomers). Whether or not a polymerization reaction is reversible or not depends on the Gibb's free energy of the process, which can be used to predict exactly how much of your monomers will be in polymer state and how much would be in free monomer state.

So now you have two key concepts here: 1- is the polymerization a dehydration reaction? and 2- is the polymerization reaction reversible at the considered conditions? If the answer is yes to both questions, then it is possible that placing your polymer in water will lead to depolymerization.

I say it is possible because even if the two conditions are met, it still doesn't mean your polymer will break down. That's because you also need to consider a third concept: activation energy and reaction rates.

Even if Gibb's free energy predicts that a reaction will occur, the rate of the reaction will depend on the activation energy. You can think of the two states, monomer and polymer, as two sides of a mountain, and the activation energy as the height of the mountain. The higher the mountain, the harder it would be to go from one side to the other. Similarly, the higher the activation energy, the harder it would be for the monomers to go into polymer state (and vice versa).

Sometimes the activation energy is high enough that even a polymer that was formed by a dehydration reaction would not fall apart in water. Examples of these types of polymers, believe it or not, include DNA and protein. There are all polymers that would NOT automatically depolymerize if you put them in water. DNA and proteins are actually fairly stable oligomers.

This is where enzymes come in. What enzymes do is equivalent to lowering the height of the mountain, so that things can go from one side to the other more easily (and faster). Now here's the kick. Enzymes can decrease the height for crossing in both directions, or they can decrease it in just one direction. If the enzyme decreases the energy in the direction of polymerization, then the monomers will polymerize and stay there. If the enzyme decreases the activation energy in the reverse direction, then a polymer would fall apart and stay as monomers.

This is why you need proteases to break down proteins, and nucleases to break down DNA, which would NOT readily break down on their own by simply placing them in water.

If I synthesize a polypeptide and throw it in water, it won't automatically hydrolyze. If I synthesize an oligonucleotide and throw it in water, it won't automatically hydrolyze. For that, I have to use proteases and nucleases.

Conclusion? The claim in the OP is a false generalization of a very specific scenario within a very specific type of polymerization reaction (which ironically does not apply to DNA and proteins). I hope you are able to see that now.

Whether the original source of the claim is simply ignorant or actively trying to misinform you, I will leave to you to decide.
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Re: Wet Monomers shouldn't become polymers - but ...

Postby BioWizard on July 16th, 2017, 12:09 pm 

Bonus note: Polyacrylamide polymerization is an example of a noncondensation polymerization reaction that can be done in water. It is both spontaneous and irreversible. We do this routinely in the lab for various molecular biology work: https://en.wikipedia.org/wiki/Polyacryl ... rophoresis
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