Ribonucleic acid (RNA), a DNA analogue that was probably the first genetic material for life, spontaneously forms in basaltic lava glass, as scientists discovered. In this way, one of the ‘seeds’ of life could have formed directly on Earth.
The discovery, which has major implications for determining the origin of life on Earth and perhaps Mars, was published this Friday in the journal Astrobiology by scientists from the Foundation for Applied Molecular Evolution.
This type of glass was abundant on Earth 4,350 million years ago, and it so happens that Similar basalts and this antiquity were also present on Mars.
“Scientists studying the origins of life have disagreed in recent years,” said Steven Benner, co-author of the study. Because of the complexity of chemical processes, it is not easy to explain how life actually arose on Earth.
However, the new discovery allows for a simpler approach. The study, led by Elisa Biondi, found that long RNA molecules 100 to 200 nucleotides long, They form when nucleoside triphosphates do nothing but leach through basaltic glass.
“Basaltic glass was everywhere on Earth back then,” said Stephen Mojzsis, an Earth scientist who was also involved in the study. “A few hundred million years after the formation of the Moon, the frequent impact of asteroids and abundant volcanism on the young planet formed molten basaltic lava, which was the source of the basaltic glass. The effects also evaporated water to create dry land and provided aquifers where RNA could form,” he added.
These same effects also produced nickel, which the team showed provides nucleoside triphosphates from nucleosides and activated phosphate, which is also found in lava glass. Borate (as with borax) controls the formation of these triphosphates, again from basalt.
The same impacts that formed the glass also temporarily depleted the atmosphere with metallic cores of iron and nickel. RNA bases, whose sequences store genetic information, form in such atmospheres. The team had previously They are formed by a simple reaction between ribose phosphate and RNA bases.
a simple model
“The beauty of this model is its simplicity. “High school students can try it in chemistry class,” said Jan Pacek, who was not involved in this work but has developed a tool to detect alien genetic polymers on Mars. “Mix the ingredients, wait a few days, and detect the RNA,” he said.
He claims that this work completes a pathway that creates RNA from small organic molecules that were almost certainly present on early Earth. A single geological model, One and two carbon molecules to yield RNA molecules long enough to support Darwinian evolution.
“Significant issues are waiting to be resolved,” Benner warns. “We still don’t know how all RNA building blocks have the same general shape, a relationship known as homochirality.” Likewise, the linkages between nucleotides in material synthesized on basaltic glass may be variable. Its significance is unknown.
Mars is related to this expeditionbecause the same minerals, glass and impacts were also present on ancient Mars. However, the planet has not suffered from continental drift and plate tectonics, which have buried most of Earth’s rocks for more than 4 billion years. Thus, key moment rocks remain on the Martian surface. The final missions found all the necessary rocks there, including borate.
“If life arose in this simple way on Earth, it probably also arose on Mars,” Benner said. “This makes it even more important to seek life on Mars as soon as possible.”
Reference Work: doi:10.1126/science.add3257
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