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Metabolism May Be Older Than Life Itself And Can Start Spontaneously

haidut

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If this is indeed true I am not sure how can modern medicine continue to deny the primary role of metabolism in the human organism. The picture so far suggests that metabolism appeared first, then RNA and finally DNA. The same group published two studies. The first one showed that glycolysis can start spontaneously using metals like iron as a catalyst. The second one showed that the Krebs cycle can happen spontaneously using sulphate radicals as a catalyst. St. Gyoirgi, Warburg and Koch all wrote about the vital role of radicals for the functioning of living organisms. In modern life forms those radicals are likely the quinones like CoQ10 and vitamin K.

Spark of life: Metabolism appears in lab without cells
"...Metabolic processes that underpin life on Earth have arisen spontaneously outside of cells. The serendipitous finding that metabolism – the cascade of reactions in all cells that provides them with the raw materials they need to survive – can happen in such simple conditions provides fresh insights into how the first life formed. It also suggests that the complex processes needed for life may have surprisingly humble origins. “People have said that these pathways look so complex they couldn’t form by environmental chemistry alone,” says Markus Ralser at the University of Cambridge who supervised the research. But his findings suggest that many of these reactions could have occurred spontaneously in Earth’s early oceans, catalysed by metal ions rather than the enzymes that drive them in cells today."
"...The pathways they detected were glycolysis and the pentose phosphate pathway, “reactions that form the core metabolic backbone of every living cell,” Ralser adds. Together these pathways produce some of the most important materials in modern cells, including ATP – the molecule cells use to drive their machinery, the sugars that form DNA and RNA, and the molecules needed to make fats and proteins. If these metabolic pathways were occurring in the early oceans, then the first cells could have enveloped them as they developed membranes. In all, 29 metabolism-like chemical reactions were spotted, seemingly catalysed by iron and other metals that would have been found in early ocean sediments. The metabolic pathways aren’t identical to modern ones; some of the chemicals made by intermediate steps weren’t detected. However, “if you compare them side by side it is the same structure and many of the same molecules are formed,” Ralser says. These pathways could have been refined and improved once enzymes evolved within cells."

Metabolism may be older than life itself and start spontaneously
"...A set of chemical reactions occurring spontaneously in Earth’s early chemical environments could have provided the foundations upon which life evolved. The discovery that a version of the Krebs cycle, which occurs in most living cells, can proceed in the absence of cellular proteins called enzymes suggests that metabolism is older than life itself. Metabolism describes the fiendishly complex network of reactions that enable organisms to generate energy and the molecules they need to survive, grow and reproduce. The Krebs cycle – also known as the tricarboxylic acid (TCA) cycle – is at the heart of this network. It describes a circular chain of reactions that generates precursors of amino acids and lipids used to build proteins and membranes, and molecules that help the cell to produce its energy. But how did such a complex cycle develop in the first place?"
"...Ralser previously showed that two other crucial metabolic pathways – glycolysis and the pentose phosphate pathway – could be catalysed by metal ions present on early Earth rather than the enzymes that catalyse them in modern cells. But sceptics of the “metabolism first” idea have pointed out that these pathways only seem to run in one direction, whereas earliest life would have needed both in order to work, and the starting material for these pathways, glucose, is unlikely to have existed on early Earth. Unable to so far provide a satisfactory answer to these problems, Ralser has shifted his focus to the Krebs cycle. Unlike with glucose, the chemicals involved at various points of the Krebs cycle have been identified on meteorites and in laboratory recreations of Earth’s early oceans – so we know they were around. “We may not be able to solve where glucose comes from so easily,” says Ralser. “But if we can provide proof that the Krebs cycle could originate from a single, non-enzymatic catalyst, then we would have a very strong case that what we say about the origins of metabolism is true.” So his team took chemicals involved in the Krebs cycle and exposed them to chemicals that would have been present in early ocean sediments. Nothing happened, until they introduced a compound called peroxydisulphate, a source of highly reactive agents called sulphate radicals. This triggered a sequence of 24 chemical reactions that were very similar – although not identical – to those seen in the Krebs cycle today. “The most surprising thing is that again a single molecule acts as the catalyst for all of the reactions we discovered,” says Ralser. “The simplicity of it is super-exciting because it gives you a plausible feeling about how it could have all started.”
 

aguilaroja

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...The picture so far suggests that metabolism appeared first, then RNA and finally DNA. The same group published two studies. The first one showed that glycolysis can start spontaneously using metals like iron as a catalyst. The second one showed that the Krebs cycle can happen spontaneously using sulphate radicals as a catalyst. St. Gyoirgi, Warburg and Koch all wrote about the vital role of radicals for the functioning of living organisms. In modern life forms those radicals are likely the quinones like CoQ10 and vitamin K.

Spark of life: Metabolism appears in lab without cells

Metabolism may be older than life itself and start spontaneously

Historical perspective for newer readers:
The primacy of basic metabolic functions in life’s origins was advanced by Oparin, Haldane and others in the 1920’s. The physicist Freeman Dyson was a renewed champion for early metabolism in the 1990’s.

Adaptive substance, creative regeneration: Mainstream science, repression, and creativity
“In the early 1920s, Bungenberg de Jong and A.I. Oparin showed how solutions of organic substances could spontaneously organize themselves into complex systems, with differentiated parts.”

Freeman Dyson - Wikipedia
"Dyson favors the dual origin concept: Life first formed cells, then enzymes, and finally, much later, genes. This was first propounded by the Russian Alexander Oparin.[50] J. B. S. Haldane developed the same theory independently.[51] Dyson has simplified things by saying simply that life evolved in two stages, widely separated in time."
 

haidut

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Historical perspective for newer readers:
The primacy of basic metabolic functions in life’s origins was advanced by Oparin, Haldane and others in the 1920’s. The physicist Freeman Dyson was a renewed champion for early metabolism in the 1990’s.

Adaptive substance, creative regeneration: Mainstream science, repression, and creativity
“In the early 1920s, Bungenberg de Jong and A.I. Oparin showed how solutions of organic substances could spontaneously organize themselves into complex systems, with differentiated parts.”

Freeman Dyson - Wikipedia
"Dyson favors the dual origin concept: Life first formed cells, then enzymes, and finally, much later, genes. This was first propounded by the Russian Alexander Oparin.[50] J. B. S. Haldane developed the same theory independently.[51] Dyson has simplified things by saying simply that life evolved in two stages, widely separated in time."

Thanks. So, would you say that in the first stage (without genes) cells simply divided as a method of reproduction while sexual reproduction/selection started when DNA came along? I am asking because without DNA I don't see a reason for sexual reproduction/selection to exist - i.e. no benefit to "mingling" with other individuals and the message that they carry.
If life did fine without genes for so long, I wonder what purpose the genes have then? Maybe they are simply a form of concentrated sexual memory from the mingling of millions of past generations to help the current organism optimize current mate selection? Have come across anything like that discussed in the literature? I really do not see much evidence for genes determining survival fitness so then the only thing that remains as their role is sexual selection.
 

aguilaroja

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Joined
Jul 24, 2013
Messages
850
Thanks. So, would you say that in the first stage (without genes) cells simply divided as a method of reproduction while sexual reproduction/selection started when DNA came along? I am asking because without DNA I don't see a reason for sexual reproduction/selection to exist - i.e. no benefit to "mingling" with other individuals and the message that they carry.
If life did fine without genes for so long, I wonder what purpose the genes have then? Maybe they are simply a form of concentrated sexual memory from the mingling of millions of past generations to help the current organism optimize current mate selection? Have come across anything like that discussed in the literature? I really do not see much evidence for genes determining survival fitness so then the only thing that remains as their role is sexual selection.

I plead both general and specific ignorance. I have contemplated the primacy of metabolism and contrarian de-emphasis of DNA-hype for some time.

I have not followed “origin of life” publication strands much recently. Academic approaches seemed dominated by un-Peaty views of the primacy of the inert (“physics”) and incidental (“abiogenesis”) nature of, well, Life (biology) and Nature.

Freeman Dyson described his dual origin ideas in terms of hardware first (protein, representing metabolism) then software (nucleic acids, representing genetics). I was uncomfortabe with the analogy. To Dyson’s great credit, he renewed academic interest and encouraged exploration & testing.

AFAIK, the “RNA world” idea dominates recent thinking. Leslie Orgel had some interesting ideas, including emphasis on the RNA function of catalysis. Some RNA-world thinking seems a little too wishful retrofitting to DNA hype.
RNA world - Wikipedia

There’s understandable consideration of the timing of the appearance of mitochondria in relation to both cell division and development of eukaryotes. I am a casual observer, and have not yet sifted recent speculation from insight.

Mitochondria, the Cell Cycle, and the Origin of Sex via a Syncytial Eukaryote Common Ancestor. - PubMed - NCBI
“…symbiotic association led to the origin of mitochondria and gene transfer to host's genome, generating a nucleus and a dedicated translational compartment, the eukaryotic cytosol, in which-by virtue of mitochondria-metabolic energy was not limiting.”
“ We propose that eukaryotic chromosome division arose in a filamentous, syncytial, multinucleated ancestor, in which nuclei with insufficient chromosome numbers could complement each other through mRNA in the cytosol and generate new chromosome combinations through karyogamy. A syncytial...eukaryote ancestor, …would account for…eukaryotic chromosome separation…more conserved than…eukaryotic cell division.”
“The origin of eukaryotes was the origin of vertical lineage inheritance, and sex was required to keep vertically evolving lineages viable… The origin of mitochondria was, in this view, the decisive incident that precipitated symbiosis-specific cell biological problems, the solutions …were the salient features that distinguish eukaryotes from prokaryotes….”

Membranes, energetics, and evolution across the prokaryote-eukaryote divide
“Prokaryotes dominate eukaryotes both on a numerical and biomass basis (Whitman et al., 1998; Lynch, 2007), and harbor most of the biosphere’s metabolic diversity.”
“…once cell-size scaling is taken into account, the bioenergetic features of eukaryotic cells are consistent with those in bacteria. This implies that the mitochondrion-host cell consortium that became the primordial eukaryote did not precipitate a bioenergetics revolution.”

Physiology, phylogeny, early evolution, and GAPDH. - PubMed - NCBI
“The chloroplast cytosol isoenzymes of D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) harbor evidence of major events in the history of life: the origin of the first genes, the bacterial-archaeal split, the origin of eukaryotes, the evolution of protein compartmentation during eukaryote evolution, the origin of plastids, and the secondary endosymbiosis among the algae with complex plastids.”
 

haidut

Member
Joined
Mar 18, 2013
Messages
19,278
Location
USA / Europe
I plead both general and specific ignorance. I have contemplated the primacy of metabolism and contrarian de-emphasis of DNA-hype for some time.

I have not followed “origin of life” publication strands much recently. Academic approaches seemed dominated by un-Peaty views of the primacy of the inert (“physics”) and incidental (“abiogenesis”) nature of, well, Life (biology) and Nature.

Freeman Dyson described his dual origin ideas in terms of hardware first (protein, representing metabolism) then software (nucleic acids, representing genetics). I was uncomfortabe with the analogy. To Dyson’s great credit, he renewed academic interest and encouraged exploration & testing.

AFAIK, the “RNA world” idea dominates recent thinking. Leslie Orgel had some interesting ideas, including emphasis on the RNA function of catalysis. Some RNA-world thinking seems a little too wishful retrofitting to DNA hype.
RNA world - Wikipedia

There’s understandable consideration of the timing of the appearance of mitochondria in relation to both cell division and development of eukaryotes. I am a casual observer, and have not yet sifted recent speculation from insight.

Mitochondria, the Cell Cycle, and the Origin of Sex via a Syncytial Eukaryote Common Ancestor. - PubMed - NCBI
“…symbiotic association led to the origin of mitochondria and gene transfer to host's genome, generating a nucleus and a dedicated translational compartment, the eukaryotic cytosol, in which-by virtue of mitochondria-metabolic energy was not limiting.”
“ We propose that eukaryotic chromosome division arose in a filamentous, syncytial, multinucleated ancestor, in which nuclei with insufficient chromosome numbers could complement each other through mRNA in the cytosol and generate new chromosome combinations through karyogamy. A syncytial...eukaryote ancestor, …would account for…eukaryotic chromosome separation…more conserved than…eukaryotic cell division.”
“The origin of eukaryotes was the origin of vertical lineage inheritance, and sex was required to keep vertically evolving lineages viable… The origin of mitochondria was, in this view, the decisive incident that precipitated symbiosis-specific cell biological problems, the solutions …were the salient features that distinguish eukaryotes from prokaryotes….”

Membranes, energetics, and evolution across the prokaryote-eukaryote divide
“Prokaryotes dominate eukaryotes both on a numerical and biomass basis (Whitman et al., 1998; Lynch, 2007), and harbor most of the biosphere’s metabolic diversity.”
“…once cell-size scaling is taken into account, the bioenergetic features of eukaryotic cells are consistent with those in bacteria. This implies that the mitochondrion-host cell consortium that became the primordial eukaryote did not precipitate a bioenergetics revolution.”

Physiology, phylogeny, early evolution, and GAPDH. - PubMed - NCBI
“The chloroplast cytosol isoenzymes of D-glyceraldehyde-3-phosphate dehydrogenase (GAPDH) harbor evidence of major events in the history of life: the origin of the first genes, the bacterial-archaeal split, the origin of eukaryotes, the evolution of protein compartmentation during eukaryote evolution, the origin of plastids, and the secondary endosymbiosis among the algae with complex plastids.”

Interesting, thanks. In case you have not seen it, here is one of those pushes to explain evolution with RNA.
Not The "selfish Gene"(DNA), But RNA Be The Driver Of Evolution
 

aguilaroja

Member
Joined
Jul 24, 2013
Messages
850
This article is at least suggestive of a more vivified view of environment in early life:

Emergence of Life on Earth: A Physicochemical Jigsaw Puzzle. - PubMed - NCBI
“…Earth-Moon rotations deliver two kinds of regular cycling energies: diurnal electromagnetic radiation and seawater tides. (3) Emerging colloidal phases cyclically nucleate and agglomerate in seawater and consolidate as geochemical sediments in tidal zones, creating a matrix of microspaces. (4) Some microspaces persist and retain memory from past cycles, and others re-dissolve and re-disperse back into the Earth's chemical reservoir. (5) Proto-metabolites and proto-biopolymers coevolve with and within persisting microspaces…”
 

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