Building Blocks of Life May Have Formed in Water Droplets

Reactions that generate fundamental components of the cell run smoothly in microdroplets, study shows.

By | October 23, 2017

PXHEREReactions in tiny droplets of water may have given rise to some of the molecules essential for the origin of life.

These reactions, which require a lot of energy in large vats of liquids, are nearly spontaneous in small droplets, researchers report today (October 23) in the Proceedings of the National Academy of Sciences. The finding suggests that the building blocks of life, including DNA, RNA, and materials used in cell walls and energy storage, may have been generated in mists and sea sprays on early Earth.

“Did this happen billions of years ago? We don’t know,” study coauthor Richard Zare, a chemist at Stanford University, tells The Scientist. “But this is one plausible mechanism for prebiotic chemistry.”

In Earth’s history, the transition from non-life to life happened relatively quickly. About 4 billion years ago, the planet was a molten ball of lava. But it’s thought that by at least 3.7 billion years ago, single-celled organisms existed. So, Zare says, the question becomes, “How did Earth go from non-life to life?”

See "In Canada, Signs of Life Nearly 4 Billion Years Old"

Zare and colleagues wanted to see if sea spray might have played a role in the reactions that generated prebiotic material, so they used nitrogen gas to generate a fine mist out of a solution of sugar, an RNA base called uracil, and phosphoric acid. After about 300 milliseconds, the team sniffed out the resulting compounds in the mist using a mass spectrometer, and found they included sugar phosphates and uridine—a component of RNA made up of uracil plus a simple sugar.

The initial compounds had undergone phosphorylation reactions, the team realized—a significant finding because phosphorylation is central to all metabolism in life today. Organisms use enzymes to catalyze the reactions, but these processes must have occurred non-enzymatically in the prebiotic environment to generate phosphorylated organic compounds, notes University of California, Santa Cruz biologist David Deamer in an email to The Scientist. “Aerosol chemistry is one possibility” for how that might have happened, he says.

Phosphorylation reactions are a classic example of how simple organic molecules morph into high-energy biopolymers. Understanding how such polymers form remains a challenge in origin of life research, Veronica Vaida, a physical chemist at the University of Colorado Boulder, writes in an email to The Scientist. The results of the new study show that reactions between phosphoric acid and sugars can occur without an external charge, condensing matter, or organic phosphates as an energy source, she notes; consequently, they may have occurred under the conditions present on ancient Earth.

Vaida adds that for the most part, only hydrothermal vents, rocks, clays, minerals, and the ocean as a whole have been considered as prebiotic reaction environments. In 2000, she and colleagues proposed that atmospheric aerosols could be prebiotic chemical reactors. The new paper offers compelling evidence that this hypothesis may be correct, she says.

See "RNA World 2.0"

If foundational phosphorylation reactions did take place in water droplets, what happened next to the resulting molecules? “If the aerosols were produced by wave action in the ocean, they would simply fall back into bulk phase water and the sugar phosphates would hydrolyze after awhile,” Deamer suggests. “However, if they were produced by waves breaking on a shoreline, the aerosols would fall into nearby fresh water pools just as they do now in places like Hawaii. The organic compounds would be concentrated as the pools evaporated, and this would allow another series of reactions to begin, including the incorporation of sugar phosphates into polymers like nucleic acids.”

But as Zare acknowledges, “We can’t know for sure. We weren’t there.”

I. Nam et al., “Abiotic Production of Sugar Phosphates and Uridine Ribonucleoside in Aqueous Microdroplets,” PNAS, doi: 10.1073/pnas.1714896114, 2017.

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Avatar of: Qedlin

Qedlin

Posts: 2

October 24, 2017

With respect, speculation about the contents of microdots of water has no geochemical relevance for primordial Earth. The issue of contamination, concentrations as well as coincidence and coloction of critical materials refutes any naturalistic theory of the origin of life. Scientific consideration of all the 'ifs' and "may haves" pushes any serious possibility of validity of this approach into the same category of Dawinian myths of "warm little pohds." Higly inplausible.

Avatar of: Qedlin

Qedlin

Posts: 2

October 24, 2017

With respect, speculation about the contents of microdots of water has no geochemical relevance for primordial Earth. The issue of contamination, concentrations as well as coincidence and colocation of critical materials refutes any naturalistic theory of the origin of life. Scientific consideration of all the 'ifs' and "may haves" pushes any serious possibility of validity of this approach into the same category of Darwinian myths of "warm little ponds." Highly implausible.

Avatar of: James V. Kohl

James V. Kohl

Posts: 481

October 24, 2017

From the journal article: ...

...we show that sugar phosphates and a ribonucleoside form spontaneously in microdroplets, without enzymes or an external energy source.

Something seems to be missing from what others may believe about the anti-entropic virucidal energy-dependent creation of life.

See for instance: Dependence of RNA synthesis in isolated thymus nuclei on glycolysis, oxidative carbohydrate catabolism and a type of “oxidative phosphorylation” (1964)

The synthesis of RNA in isolated thymus nuclei is ATP dependent.

That suggests there is no such thing as "abiotic production." It is more likely that Schrodinger (1944) was correct:

Indeed, in the case of higher animals we know the kind of orderliness they feed upon well enough, viz. the extremely well-ordered state of matter in more or less complicated organic compounds, which serve them as foodstuffs. After utilizing it they return it in a very much degraded form -not entirely degraded, however, for plants can still make use of it. (These, of course, have their most power supply of ‘negative entropy’ the sunlight.) (pp. 73 and 74)

See also: Olfaction Warps Visual Time Perception

The authors linked the quantized energy-dependent creation of the sense of smell in bacteria from the physiology of pheromone-controlled reproduction to all biophysically constrained biodiversity in the context of the space-time continuum and our visual perception of energy and mass. 
 

Avatar of: Roy Niles

Roy Niles

Posts: 113

October 25, 2017

The chemicals of life may have been formed by contacts with water, but living things are defined by their ability to make active and reactive choices.  Which would seem to indicate that some primitive version of intelligent energy was involved. We can only theorize as to how any such intelligent entities may have been developed and evolved in the universe at some ancient time, and the probability seems to be that such intelligent energy has always been a universal entity!

Avatar of: JohnnyMorales

JohnnyMorales

Posts: 30

Replied to a comment from Qedlin made on October 24, 2017

November 14, 2017

Is that what your religion tells you, because scientifically the only thing that utterly groundless is your spurrous string of conclusions you make without any proof whatsoever.

That you believe them is not proof.

That you deny the proof of evolution is proof you're belief is fact-free faith based and really has no bearing on what the article was about.

Avatar of: JohnnyMorales

JohnnyMorales

Posts: 30

November 14, 2017

I thought that more recent theorizing concluded the notion that the Earth was ever a ball of molten lava as likely false due to the amount of time that passed as the Earth formed.

It was long enough to ensure that thin, solid crust would quickly form even after massive impacts giving life a place to start far sooner than it was assumed if the Earth had actually been a ball of molten lava.

This isn't to say that during the formation of the bulk of the planet there'd be seas of magma on the surface.

Rather only that the entire surface of the planet was likely never completely molten as enough time passed between massive liquifying impacts to prevent total melting of the Earth's surface.

What is true is the crust of the young Earth was extremely thin and the rapid process of differention probably did create a world that was molten under a thin crust.

Regardless that thin crust would be enough for water to condence on the surface and kick start the process to create life, probably many times, before it finally took hold.

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