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How Was The First Cell Made?


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#1 EmmaWhat

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Posted 16 August 2016 - 05:31 PM

I am not a biologist and looking to find some sort of description of the question above, if we know at all.  Rather, what is our best hypothesis?


Edited by EmmaWhat, 16 August 2016 - 05:48 PM.


#2 A-wal

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Posted 16 August 2016 - 06:35 PM

A chemical reaction close to a hydrothermal vent or a lightning strike in a pool of amino acid.



#3 exchemist

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Posted 18 August 2016 - 08:21 AM

I am not a biologist and looking to find some sort of description of the question above, if we know at all.  Rather, what is our best hypothesis?

I do not think we really know at all. The first requirement of a cell is a membrane that separates it from the environment, while allowing certain chemicals to cross it. Various speculations have been made for what the first such membrane might have been. For example this article: http://www.nature.co...e080703-16.html

 

suggests that fatty acids can form a useable bilayer.  But I have not read anywhere that there is any sort of consensus on this point. 



#4 A-wal

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Posted 18 August 2016 - 10:10 AM

Yea I suppose the start of life wouldn't have been a cell, different question.

 

So actually was the first life, RNA? The major steps I know of are RNA, DNA, single cell life form.

 

Is that right? Any major missing steps?



#5 exchemist

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Posted 18 August 2016 - 11:05 AM

Yea I suppose the start of life wouldn't have been a cell, different question.

 

So actually was the first life, RNA? The major steps I know of are RNA, DNA, single cell life form.

 

Is that right? Any major missing steps?

Actually there is another thread in this section about the "metabolism first" model of abiogenesis. According to that idea, metabolic reactions may have preceded even RNA. 

 

I honestly think we are in danger of thinking science knows more about abiogenesis than it actually does. There are lots of fascinating hypotheses for elements of what is required to enable life to start, but so far as I can see that is all they are: hypotheses. For example there was a rather brilliant observation I read recently that various inorganic minerals adsorb the D and L enantiomers of chiral organic molecules to different degrees, thereby possibly accounting for why life is selective in the choice of "handedness" of organic building blocks. But nobody can say how this might actually have taken place in detail - just that there is a plausible route to making a selection, if certain mineral surfaces were important to the process.

 

It all seems to go like that. Tantalising snippets, but no real coherent theory.



#6 CraigD

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Posted 18 August 2016 - 02:31 PM

I honestly think we are in danger of thinking science knows more about abiogenesis than it actually does.
... Tantalising snippets, but no real coherent theory.

I agree.

50 years ago, the formation of the solar system was in a similar state, with lots of sensible competing alternative hypotheses, and no compelling way to distinguish the right from the wrong ones. Then electronic computers got faster and cheaper, allowing increasingly detailed simulation of the formation of the solar system to be run, and the current planetesimal hypothesis came out on top. Better telescopes observed extra-solar systems in various stages of formation, and their observations agreed with the models, and the science on the subject settled.

What happened here is that computer modeling made it virtually possible to do in less than a year an experiment that, if done in reality, would take a protostellar cloud and 50,000,000 years or so, while astronomy provide the mean to spy on the experiment in reality happening at great distances, which isn’t as good at exemplifying, but much better at confirming, the hypotheses.

A similar revolution in simulation hasn’t happened yet in pre-biotic chemistry. Landmark experiments in abiogenesis are mostly done in reality, like the Miller–Urey experiment. Such experiments scale down in mass well – they would’t require an Earth-size mass of solar system stuff, just a table-top, or at worst, a bio-dome’s worth or so – but don’t scale down in time much or at all – you’d have to wait 500,000,000 years or so to get results.

A lot of folks are working on chemistry computer simulation programs, but they’re intrinsically more complicated, and thus harder to write, and take better hardware to run fast enough, than solar system simulators. On top of that, while how the solar system formed is a question of mostly purely scientific interest, how biochemistry works is of intense, personal interest to people hoping to use the knowledge to reduce human suffering – that is, medical and pharmaceutical folk – and the most lucrative pursuit there is. So the immediate focus on “artificial life” simulation programs is modeling realistic, modern cells to see how they react to disease, drugs and therapies, with abiogenesis taking a far back seat.

Still, the only way I can imagine science settling on an abiogenesis hypothesis as it has a solar system formation one is through computer modeling. I suspect the computers needed won’t be the purely electronic ones we’re used to, but hybrids with biological processing elements, because computations done constantly in tiny biological cells using tiny amounts of energy, like folding proteins from their expressed to their finished shapes, remain beyond our ability to write programs for that can run on an electronic computer. I predict the future of computer engineering will by squishy with “biokleptic nanotechnology”.

#7 A-wal

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Posted 19 August 2016 - 03:28 AM

I thought the formation of star systems was still in question because a cloud of gas and dust won't collapse on its own no matter how long you wait and it needs something to kickstart it like a shockwave from a supernova and there's not enough supernovae to explain all the stars?

 

Wouldn't it be amazing if there is no abiogenesis and life is always under the surface and just needs the right conditions to fully emerge. Not sure how realistic that is but it's a nice thought.



#8 HydrogenBond

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Posted 01 September 2016 - 04:56 PM

Water was the key to the formation of the first cells. This can be inferred from the observation that there is no substitute for water. In experiments, if we took away the water and add any other solvent, there is no life in any cell, even if we maintain all the organics. The organics do not contain life. Water is needed for folding, for signally and for energetics, as well as other things, all of which make life possible. You can dehydrate yeast and they become inanimate, You add back water and life appears. 

 

Water self hydrogen bonds to form order, even in the liquid state. Organics add potential to a water matrix by disrupting the low energy order. Evolution is about altering the organics to minimize the potential within the water matrix.

 

For example, if we added lipids to water, stir and let the mixture settle, the water will attempt to lower potential by reforming the matrix. The lipids will need to phase separate to help minimize potential. The result is the membrane.

 

All the key biomolecules contain hydrogen bonding groups, such as the template relationship along the DNA. This addendum is a concession to the needs of water. It allows all the bio-material to lower potential in the matrix. In fact, the DNA is the most hydrated molecule in the cell, meaning it was a goal and final molecular milestone. 

 

If you burn any organic in the cell, in the presence of oxygen, one of your products is water. Water is not only the animator and shaper of life, but water is also the  energy floor of life. All the organics exist at higher potential; can be burned to water.

 

This suggests that one of the first pre-life processes was a crude type of metabolism that could lower the potential between the organics and water, with the release of energy. 



#9 CraigD

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Posted 18 September 2016 - 12:14 PM

I thought the formation of star systems was still in question because a cloud of gas and dust won't collapse on its own no matter how long you wait and it needs something to kickstart it like a shockwave from a supernova and there's not enough supernovae to explain all the stars?

While a precise computer simulation of a protostellar cloud is beyond our computing capabilities, so explanations of how they collapse into stars involve some guessing, I’m not aware of any major scientific worries about lack of mechanisms. All cloud collapse takes are local areas of supercritical density, which can happen when clouds collide with each other, cloud-like matter from supernovas or supermassive black hole disk activity, perhaps interactions with massive sub-stellar objects like rogue planets and brown dwarfs, or, given enough time, purely internal turbulance.
 

Wouldn't it be amazing if there is no abiogenesis and life is always under the surface and just needs the right conditions to fully emerge. Not sure how realistic that is but it's a nice thought.

I think that thought is of a kind of panspermia – the idea that viable biological organisms strudy enough to survive both the hot and cold vacuum of space and the violence of planet formation or collision exist, possibly widespread. I doubt this is true, though, because we’ve gotten a lot of samples of the Moon and analyzed it down to the atomic level, without finding anything like that. So if such organisms are out there, they’re not ubiquitous.
 

Water was the key to the formation of the first cells. This can be inferred from the observation that there is no substitute for water. In experiments, if we took away the water and add any other solvent, there is no life in any cell, even if we maintain all the organics. The organics do not contain life.

Almost certainly water it key to all of the biology on earth, even that of the weirdest extremophiles, but inferring from this the impossibility of life using any other solvent ignores a sizable body of scientific literature on the subject. The Wikipedia section “non-water solvents” is a reasonable entry into this literature.

On a philosophical/language note, I think the phrase “contains life” harks back to the pre-scientific era where life was considered a distinct “essence” from that of non-living matter. We now know that life is not a substance contained in matter, but a phenomenon that arises when matter is arranged in a special way. The same chemical elements are non-living things as in living, so life is, I think, best considered information embodied in the arrangement of matter than emerging from one kind or another of it.

#10 A-wal

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Posted 19 September 2016 - 12:45 PM

I think that thought is of a kind of panspermia – the idea that viable biological organisms strudy enough to survive both the hot and cold vacuum of space and the violence of planet formation or collision exist, possibly widespread. I doubt this is true, though, because we’ve gotten a lot of samples of the Moon and analyzed it down to the atomic level, without finding anything like that. So if such organisms are out there, they’re not ubiquitous.

What about Mars? I know those little worm looking things haven't been confirmed to be life but it hasn't been ruled out has it? I think they can't tell but they definitely look on the surface like they could have been alive.



#11 Moontanman

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Posted 20 September 2016 - 04:20 PM

What about Mars? I know those little worm looking things haven't been confirmed to be life but it hasn't been ruled out has it? I think they can't tell but they definitely look on the surface like they could have been alive.

 

 

What about the tentacled creature recently photographed on Mars? 



#12 Moontanman

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Posted 20 September 2016 - 04:22 PM

I am not a biologist and looking to find some sort of description of the question above, if we know at all.  Rather, what is our best hypothesis?

 

 

If you are really interested in the cutting edge science I can provide you with a lecture that pretty much explains the process but asking how it was made is begging the question... 



#13 CraigD

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Posted 20 September 2016 - 10:01 PM

I think that thought is of a kind of panspermia – the idea that viable biological organisms strudy enough to survive both the hot and cold vacuum of space and the violence of planet formation or collision exist, possibly widespread. I doubt this is true, though, because we’ve gotten a lot of samples of the Moon and analyzed it down to the atomic level, without finding anything like that. So if such organisms are out there, they’re not ubiquitous.

What about Mars? I know those little worm looking things haven't been confirmed to be life but it hasn't been ruled out has it?

I think you mean the nanoscopic features on meteorite ALH84001. While it’s fairly certainly from Mars, whether its features are evidence of nanobacteria or the result of something non-biological is scientifically unclear.

I think the hypothesis that life on Earth originated on Mars is one of the more accepted-as-plausible panspermia hypotheses, but still a highly speculative one. My best guess is that life may have formed via abiogenesis on Mars, but if it did, is even more likely to have formed via abiogenesis on Earth.

I’m hopeful that as the bioscience capabilities of Mars lander/rovers improve, or there’s a manned mission with advanced bioscience capabilities, the question of whether there is or was life on Mars will be settled.
 

What about the tentacled creature recently photographed on Mars?

You mean this?
Alien-Snake-Found-On-Mars.jpg

Looks like a circular dirt berm to me. I don’t think it moves, either, which is pretty uncharacteristic of snake/tentacle alien.s ;)

#14 A-wal

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Posted 21 September 2016 - 06:10 AM

What about the tentacled creature recently photographed on Mars? 

If your point was that the meteorite worms are no more likely to have been alive than that 'octopus' then it's a bit different to actually have them in the lab to study and rule out the possibility that they're fossilised life forms, something that hasn't happened so there must be a fairly reasonable chance that they were alive.

 

I think the hypothesis that life on Earth originated on Mars is one of the more accepted-as-plausible panspermia hypotheses, but still a highly speculative one. My best guess is that life may have formed via abiogenesis on Mars, but if it did, is even more likely to have formed via abiogenesis on Earth.

If that's true and life formed independently on two neighbouring planets that would be by far the most profound discovery of all time. It would mean that life is common throughout the universe and with the amount of stars and planets, that's a LOT of life.


Edited by A-wal, 21 September 2016 - 06:11 AM.


#15 Looncall

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Posted 03 December 2016 - 04:36 PM

I am not a biologist and looking to find some sort of description of the question above, if we know at all.  Rather, what is our best hypothesis?


A minor point: better to say that early life "happened" rather than that it was "made". Less unfortunate baggage that way.

#16 A-wal

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Posted 03 December 2016 - 05:11 PM

Made by nature. ;)



#17 HydrogenBond

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Posted 04 December 2016 - 08:03 AM

Biology perpetuates a conceptual problem for itself, than makes the question of the formation of life harder to answer. Biology assumes life is organic-centric; DNA, RNA and Protein. The fact remains, lab tests have shown that none of these molecules will work if we take away the water. Lab tests have also shown you cannot substitute any other solvent and make the DNA or the proteins work. From this basic data, I would conclude that life is based on a partnership between water and organics, with both parts needed to create life. 

 

If you work under the copartner assumption; water-organic are a team, like a husband and wife, it becomes easier to explain the formation of life, because this team pushes from two different direction toward a middle. If you only push in one direction you keep on going and never stop. You need to depend on bumping into the right things in a random way. 

 

For example, consider water and oil; very basic water and organic partnership. If we try to blend these an emulsion will appear. If stop adding energy and allow the energy to drop, the emulsion will separate into two layers. This separation result is repeatable and does not come out differently each time. The phase separation into two layers in governed by chemical determinism; being pushed from two sides, If we take lipids and water, we get a bi-layered membranes. Water and organics, when blended, create potentials with each other causing them to separate in ways that reduces this potential. This allows repeatable order instead of randomness. 

 

If you assume just organics, a bi-layered membrane seems like a random situation that might appear based on odds. If you add water, the dice become loaded with this now a sure thing. The configuration of the DNA in water reflects a low energy configuration relative to amount of water plus the atoms of the DNA. If we have just DNA, there is a different lowest energy configuration. If we add some water the configuration of the pure DNA changes, to reflect the potential between the DNA and the amount of water that was added. At the maximum water, we have beta-DNA, which is bioactive. 

 

The water-organic team helps life to appear, better than any other solvent, because water is very stable. Water has not changed since the beginning of evolution.The organic side of the team has been modified from simple beginnings into complex variations. Water acts like a stable energy floor, so all the change have to appear on the organic side.

 

If we tried to start life, with any organic solvent, these solvents by being organic, can be modified when the potential between solvent and structures gets high enough. The problem that would arise is, if the solvent becomes modified, the potential with all the organic parts will changes, so the evolving pre-life processes might stop working. With water so stable, even high energy milestone can be reached, with water steady as ever. Lipids have formed membranes the same way for eons, because water is always the same; stable floor. We not have to reinvent the membrane due to solvent changes but can modify it even more via continuity. 

 

One useful observation, that tells us somethings about the evolution of life, is DNA is the most hydrated molecule in the cell. The DNA was not a random thing, but was a goal induced by the team. In other words, one way to reduce the potential between the organics and water, with water unable to change, it to modify the organics more and more to the needs of the water. The most hydrated molecule of life become a goal. DNA was inevitable based on the water-organic partnership. 

 

The team approach, like the husband and wife, means there not just one way, but two ways at the same time, with compromises needed to reached, to reflect the needs of each, with these compromises having sweet spots; milestones. Lowest potential is when both husband and wife are satisfied with the result. 


Edited by HydrogenBond, 04 December 2016 - 08:05 AM.