(ORDO NEWS) — Earth is the only planet in the universe known to have life, but even that was desolate at first. About 4 billion years ago, something happened that gave our sterile breed the building blocks of life.
For example, amino acids must have existed before there were proteins on Earth, a vital component of all life forms.
The origin of amino acids on Earth remains unclear, but some scientists suspect that these organic compounds were delivered from space by meteorites.
In a new study, researchers reveal details of how this could have happened, supporting the idea that meteorites helped establish life on Earth.
The study shows how a certain class of meteorites called chondrites can produce their own amino acids through reactions triggered by gamma rays from the meteorites themselves.
Meteorites. these are pieces of ancient debris left over from the infancy of the solar system that crash into a planet or moon. Different types of meteorites are made up of different materials.
Chondrites are stony meteorites, inside of which are mysterious spheres known as chondrules. Chondrules, composed mainly of silicate minerals, are among the oldest objects in the solar system.
Meteorites have bombarded the Earth from the very beginning, and some of the early barrages may have included carbonaceous chondrites, a relatively rare subcategory of chondrites. which contains a significant amount of water and small molecules, including amino acids.
Such meteorites may have provided the Earth with the vital ingredients for life, but how did those ingredients even end up on the meteorite?
We’re still not sure, but the new study is shedding light on how chondrites (or their parent bodies) are at least theoretically able to synthesize these compounds.
Led by cosmochemist Yoko Kebukawa of Yokohama National University in Japan, the researchers sought to answer questions from previous laboratory experiments that had examined the potential formation of amino acids on carbonaceous chondrites.
These experiments showed that simple molecules such as ammonia and formaldehyde can generate amino acids, but only in the presence of heat and liquid water. In a new study, researchers are investigating a possible heat source from a meteorite: gamma rays.
Early carbon-bearing chondrites are known to have contained aluminum-26, a radioactive element that can release gamma radiation upon decay. Kebukawa and her colleagues set out to see if this could provide the heat needed to form amino acids.
The researchers dissolved ammonia and formaldehyde in water, sealed the resulting solution in glass tubes, and then subjected the tubes to high temperatures. gamma-ray energy from the decay of cobalt-60.
As the dose of gamma radiation increased, the production of α-amino acids such as alanine, glycine, α-aminobutyric acid and glutamic acid increased along with β-amino acids such as β-alanine and β-aminoisobutyric acid.
The researchers note that these amino acids may help explain the presence of these amino acids in carbonaceous chondrites that have fallen to Earth, such as the famous Australian Murchison Meteorite.
Filled with “pre-solar” silicon carbide particles (meaning they are older than the Sun), the Murchison meteorite exploded in the sky over Murchison, Victoria on September 28, 1969 event; subsequently, people collected many fragments in the area. It has since become one of the most studied space rocks in history.
Among many interesting finds, the Murchison meteorite was filled with amino acids. To date, scientists have identified more than 70 amino acids in the meteorite, only 19 of which are known on Earth, according to Museums Victoria.
This caused widespread admiration, suggesting that life on Earth is the main chemical building block. can also be easily formed elsewhere.
In the new one, Kebukawa and her colleagues explored how amino acids could form on such a meteorite and how long it might take.
Based on their results, as well as the expected dose of gamma radiation from decaying aluminum-26 in meteorites, they estimate that it would take 1,000 to 100,000 years for this process to generate the amounts of alanine and β-alanine found on the Murchison meteorite.
While we still have a lot to learn about abiogenesis, or the spontaneous origin of life, the researchers say this study shows how reactions triggered by gamma rays can produce amino acids on a meteorite, which could give rise to life on Earth.
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