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They found amino acids as well, pretty strong evidence for a role in the delivery of organic compounds to the early Earth (though abiotic synthesis of such comp
by photochemsyn 4y ago
They found amino acids as well, pretty strong evidence for a role in the delivery of organic compounds to the early Earth (though abiotic synthesis of such compounds at hydrothermal vents is also plausible):
> "The macromolecular organic fraction of a driveway fragment was analyzed by gas chromatography–mass spectrometry (GC-MS) and found to contain structural units similar to those in other CM chondrites, including substituted benzenes and naphthalenes, various thiophenes, and polycyclic aromatic hydrocarbons. The most abundant amino acids detected in the Winchcombe meteorite were α-aminoisobutyric acid (467 ± 17 ng g−1) and isovaline (391 ± 17 ng g−1; table S23). An extraterrestrial, abiotic origin for these compounds is supported by the racemic enantiomeric ratios detected in several protein and nonprotein amino acids (e.g., D/Lalanine = 1.13 ± 0.16; D/Lisovaline = 1.06 ± 0.15)."
https://www.science.org/doi/10.1126/sciadv.abq3925 https://www.science.org/doi/10.1126/sciadv.abq3925
- lab14 4y agoIs it possible that the meteorite picked up the amino acids from Earth's atmosphere or during the impact?
- photochemsyn 4y agoIf you collect a sample of biologically synthesized amino acids, the central carbon atom will have only one stereoisomeric form, i.e. like a left hand vs. a right hand, due to how these amino acids are synthesized by biochemical systems, i.e. enzymes which only generate L-amino acids from precursors (indeed protein structure depends on this asymmetry). There are a handful of exceptions but since the amino acids collected from the meteorite are a racemic mixture (equal amounts of both left and right handed molecules), this points to abiotic synthesis.
- Aachen 4y agoSo... I understand like seven words in your comment so forgive me if I'm mistaken, but I don't think this answered the question in the comment you're responding to? They asked whether it could have been picked up in the atmosphere, not whether it's of biological origin in the first place (that would be the parent post).
- thenewwazoo 4y agoThe presumption is that it would necessarily be of biological origin if it were picked up in atmosphere.
- perihelions 4y agoI think the parent was asking if there's a separate family of abiotic amino acids in the upper atmosphere? Like from UV photochemistry stuff. (I don't know the answer either)
- inportb 4y agoThat's an interesting question and I don't know the answer! But I'd expect any amino acids produced this way to diffuse and mix with the biologic amino acids from the surface. They'd be diluted by the overwhelming amount of biological "stuff." Stereoisomers should behave the same under the influence of gravity.
- perihelions 4y ago- "Stereoisomers should behave the same under the influence of gravity." Only one way to find out! https://sci-hub.se/https://doi.org/10.1103/PhysRevLett.121.261101 https://sci-hub.se/https://doi.org/10.1103/PhysRevLett.121.2... ("Test of the Equivalence Principle with Chiral Masses Using a Rotating Torsion Pendulum")
- AnotherGoodName 4y agoBiological processes tend to clone the molecules perfectly right down to specific left or right handed orientations. So the molecules formed from a biological process will all be identical. A process that just happens to form the molecules (eg. put a bunch of elements in a soup and heat and you can also get some proteins forming) form an even mixture of configurations.
- Retric 4y agoLiving organisms use nano machines called proteins which physically make molecules like glucose out of other molecules. Some molecules can form in 2 ways that are mirror images of each other. However, making or using both versions would require having twice as many proteins so we only produce one version of anything. To visualize this consider DNA is a spiral, you could reverse everything so the spiral rotated in the other direction. But then everything interacting with DNA would also need to be built for that orientation and so forth. https://en.wikipedia.org/wiki/Mirror_life https://en.wikipedia.org/wiki/Mirror_life
- xenospn 4y agoI did not understand a single thing you just said. I'm in awe.
- grog454 4y agoAs a follow-on question to this: what is the process by which meteorites are analyzed? It seems like the contamination problem could be solved by drilling.
- Buttons840 4y agoIf life arrived on Earth from space, that's kind of a bummer because now the mystery of life's origin (our pocket of life at least) is far out there, beyond our reach.
- aflag 4y agoSort of. Earth's surface is constantly being recycled. Rocks from when life began on earth have all but completely disappeared. Meanwhile, rocks from or older than that are still completely preserved whizzing around the solar system.