April 29, 2014 at 2:21 pm #17088
Now here’s some fun stuff to chew if you’re into the evolution of life on Earth.
A reconstruction of Earth’s earliest ocean in the laboratory revealed the
spontaneous occurrence of the chemical reactions used by modern cells to synthesize
many of the crucial organic molecules of metabolism.
Previously, it was assumed that these reactions were carried out in modern cells by metabolic enzymes,
highly complex molecular machines that came into existence during the evolution of modern organisms.
The observed chemical reactions occurred in the absence of enzymes but were made possible
by the chemical molecules found in the Archean sea.
Finding a series of reactions that resembles the “core of cellular metabolism” suggests that metabolism predates the origin of life.
This implies that, at least initially, metabolism may not have been shaped by evolution
but by molecules like RNA formed through the chemical conditions that prevailed in the earliest oceans.
“Our results demonstrate that the conditions and molecules found in the Earth’s ancient oceans
assisted and accelerated the interconversion of metabolites that in modern organisms
make up glycolysis and the pentose-phosphate pathways,
two of the essential and most centrally placed reaction cascades of metabolism,” says Dr. Markus Ralser,
Group Leader at the Department of Biochemistry at the University of Cambridge and the National Institute for Medical Research.
“In our reconstructed version of the ancient Archean ocean, these metabolic reactions were particularly sensitive
to the presence of ferrous iron that helped catalyze many of the chemical reactions that we observed.”
From the analysis of early oceanic sediments, geoscientists such as Alexandra V. Turchyn from the
Department of Earth Sciences at the University of Cambridge, one of the co-authors of the study,
concluded that soluble forms of iron were one of the most frequently found molecules in the prebiotic oceans.
Markus A Keller, Alexandra V Turchyn, Markus Ralser.
Non”enzymatic glycolysis and pentose phosphate pathway”like reactions in a plausible Archean ocean.
Molecular Systems Biology, 2014; DOI: 10.1002/msb.20145228November 12, 2018 at 1:31 pm #296542
Origins of life is a fascinating topic and the advances in understand keep coming fast and furious. I think some of you are familiar with Dr. Robert Hazen and his illuminating talks about the evolution of minerals and how that set the stage for first life and and subsequent evolutionary advances.
Dr. Robert Hazen, Carnegie Institution for Science, Geophysical Laboratory
The story of Earth is a 4.5-billion-year saga of dramatic transformations, driven by physical, chemical, and—based on a fascinating growing body of evidence—biological processes. The co-evolution of life and rocks, the new paradigm that frames this lecture, unfolds in an irreversible sequence of evolutionary stages. Each stage re-sculpted our planet’s surface, each introduced new planetary processes and phenomena, and each inexorably paved the way for the next. This grand and intertwined tale of Earth’s living and non-living spheres is only now coming into focus.
Now I’ve listened to a talk by Dr. Eric Smith, who takes it back yet another step.
McCloskey Speaker Series – New Theories on the Origin of Life with Dr. Eric Smith
Featuring Dr. Eric Smith, professor at the Earth-Life Science Institute in Tokyo and the Santa Fe Institute. For most of the 20th century, complex biological views of evolution have been central to the way scientists think about the origin of life. But progress over the past 40 years in such fields as ocean exploration, microbiology, and planetary science has come together to suggest that life’s origin may have been built on a core chemical blueprint. Dr. Smith argues that we need a new understanding of the nature of life, in which the dominant, Darwinian view of a “struggle for existence” comes second, and life at its core came about as a necessary layer of our maturing planet.
Eric Smith began scientific work in high-energy physics, with Bachelor degrees in math and physics from Caltech, and a Ph.D. from the University of Texas in 1993. His work moved increasingly into topics in complex systems, …
… At SFI he began parallel threads of work in non-equilibrium thermodynamics, economics and finance, and the history of human languages, and began studying the geochemistry, biochemistry, and evolution of the earliest life. He is currently a professor and Principle Investigator of the Earth-Life Science Institute in Tokyo, and external professor at SFI. His goal is to understand the origin and nature of the living state through the many windows that science provides on it: the physical, geochemical, biochemical, ecological, and evolutionary. …
Chemical reactions depend on disequilibriums, and the flow of electrons and energy, stuff I can vaguely grasp, but certainly not explain. Still, I think it could be a fun fascinating discussion.
Anyone game? First listen to those talks and then summarize your reaction, what resonates with your thinking, what might you reject, why?November 14, 2018 at 11:00 pm #296555
Here are another couple that’ll test your assumptions.
Neil Turok Public Lecture: The Astonishing Simplicity of Everything
Published on Oct 8, 2015
On Oct. 7, 2015, Perimeter Institute Director Neil Turok opened the 2015/16 season of the PI Public Lecture Series with a talk about the remarkably simplicity that underlies nature. Turok discussed how this simplicity at the largest and tiniest scales of the universe is pointing toward new avenues of physics research and could lead to revolutionary advances in technology.
Life before genetics: autogenesis, and the outer solar system – Terrence Deacon (SETI Talks)
Streamed live on May 14, 2013
The investigation of the origins of life has been hindered by what we think we know about current living organisms. This includes three assumptions about necessary conditions: 1) that it emerged entirely on Earth, 2) that it is dependent on the availability of liquid water, and 3) that it is coextensive with the emergence of molecules able to replicate themselves.
In addition, the three most widely explored alternative general models for a molecular process that could serve as a precursor to life also reflect reductionistically-envisioned fragments of current living systems: e.g. container-first, metabolism-first, or information-first scenarios. Finally, we are hindered by a technical concept of information that is fundamentally incomplete in precisely ways that are critical to characterizing living processes.
These all reflect reductionistic “top-down” approaches to the extent that they begin with a reverse-engineering view of what constitutes a living Earth-organism and explore possible re-compositional scenarios. This is a Frankensteinian enterprise that also begins with assumptions that are highly Earth-life specific and therefore unlikely to lead to a general exo-biology.
The approach Dr. Deacon will outline instead begins from an unstated conundrum about the origins of life. The initial transition to a life-like process necessarily exemplified two almost inconceivably incompatible properties: 1) it must have involved exceedingly simple molecular interactions, and 2) it must have embodied a thermodynamic organization with the unprecedented capacity to locally compensate for spontaneous thermodynamic degradation as well as to stabilize one or more intrinsically self-destroying self-organizing processes.
This talk will explore the origins of life problem by attempting to identify the necessary and sufficient molecular relationships able to embody these two properties. From this perspective Dr. Deacon will develop a model system – autogenesis – that redefines biological information and opens the search for life’s origin to cosmic and planetary contexts seldom considered.
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