The Link Between Organic and Inorganic Life: Has It Been Found?
Scientists have recently discovered that simple peptides can organize into bi-layer membranes. A finding that suggests a “missing link” between the pre-biotic Earth’s chemical inventory and the organizational scaffolding essential to life.Bingo.“This is a boon to our understanding of large, structural assemblies of molecules,” says Emory Chemistry Chair David Lynn, who helped lead the effort, which were collaborations of the departments of chemistry, biology and physics. “We’ve proved that peptides can organize as bi-layers, and we’ve generated the first, real-time imaging of the self-assembly process. We can actually watch in real-time as these nano-machines make themselves.”
The ability to organize things within compartments and along surfaces underpins all of biology. From the bi-layer phospholipids of cell membranes to information-rich DNA helices, self-assembling arrays define the architecture of life.
“We’ve shown that peptides can form the kind of membranes needed to create long-range order,” says Emory University chemistry graduate student Seth Childers, lead author of the paper recently published by the German Chemical Society’s Angewandte Chemie. “What’s also interesting is that these peptide membranes may have the potential to function in a complex way, like a protein.”
Chemistry graduate student Yan Liang captured images of the peptides as they aggregated into molten globular structures, and self-assembled into bi-layer membranes. The results of that experiment were recently published by the Journal of the American Chemical Society.
At the Artificial Life conference which I attended recently in Denmark, about the only building-block left that wasn't in the pre-biotic assembly kit for artificial life was membranes.
It looks like simple peptides - like the ones I'm doing research on in a different context - may provide a temporary scaffolding that allows, even requires, Life to evolve. RNA first - in many ways, far more interesting than the better-known DNA that provides a convenient template for making it. The rest is just complex chemistry.
We'll see. Because there might be an intermediate step even before RNA.
From the X Files Dept: India's 'Red Rain" Mystery -Close to Being Solved?
I consider the Panspermia hypothesis to be the most likely one for the origin of Life. Possibly not Life as we know it, and it may be that non-RNA based organisms that inevitably arise in Space may have to land on a large chunk of rock with the appropriate environment to evolve further.The red rain fell sporadically over Kerala during two months in 2001 believed at first to be simply sand or dust picked up from a desert. But Godfrey Louis, a physicist at Mahatma Gandhi University in Kottayam in Kerala, examined the red particles and, unable to find DNA, suggested that they might be alien microbes that had fallen to Earth on a comet. Five years later, Louis published a theory suggesting the bugs that turned the rain red in India may have come from a comet that exploded above the Earth and seeded clouds.
This September 2010, after a further four years of studying the cells, Lewis was joined by a leading panspermia theorist from the UK, Chandra Wickramasinghe, publishing their claims that the red rain cells are unlike anything found on Earth, which inert at room temperature - begin to reproduce at 121C.
Within two hours of being exposed to the heat, "daughter cells appear within the original mother cells and the number of cells in the samples increases with length of exposure", they say in the new report....
"As a biologist, let me assure you that a cell-sized and shaped organism that reproduces, lives off LB and doesn't appear to have any nucleic acid template (DNA or RNA) is a revolutionary discovery in and of itself," according to a commentor at MIT's TechnologyReview.
Anyway, the behaviour of the Red Rain cells is as predicted by some models of pre-biotic life formation.
It fits - but whether it's true or not is another issue. More work needs doing here. I do consider it likely though that we'll know a lot more about the origins of life in the next 20 years, and even be able to manufacture life-forms entirely from non-living material. We're pretty close to that already, and I'd expect it by 2020 at the latest. Evolving it, without access to cubic parsecs of pre-biotic materials, and having a billion year timeframe - trickier. But doable.
2 comments:
A rather more likely explanation is discussed here.
http://en.wikipedia.org/wiki/Red_rain_in_Kerala
These cells appear to algal spores. If they are of extra terrestrial origin why did they continue to fall in the same region for two months? One would expect winds to cause a shift in where they fell over this period.
While I think panaspermia is probable within the Solar System I think it unlikely over interstellar distances. And in any case it merely shifts the question of the origin of life rather than answers it.
Neat paper about peptides.
I already described my position on Panspermia in detail in a prior posting, I'll link to that:
Here
Selected quotes:
...if a life form somehow made it onto Earth, it would not only be immediately competing with any life on Earth, but it may be a radically different amino acid mix - in other words, it may be unable to make proteins in this environment, and therefore die very quickly.
The evidence that Earth-based life has to do with amino acids from meteorites appears to be somewhat negative. Take the Murchison meteorite as an example - 12 amino acids found aren't used in proteins on Earth. Many of the amino acids identified have the wrong chirality for life on Earth.
I still favor the "complex chemistry will self-evolve in a big liquid chemical mixture" theory.
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