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Meteorites have long been known as carriers of key building blocks to life but so far they lacked sugars. Now, NASA has revealed that an international team has found bio-essential sugars in meteorites, a discovery that could lead to new answers as to how life may have started.
Building blocks of life
"Other important building blocks of life have been found in meteorites previously, including amino acids (components of proteins) and nucleobases (components of DNA and RNA), but sugars have been a missing piece among the major building blocks of life,” said Yoshihiro Furukawa of Tohoku University, Japan, lead author of the new study.
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“The research provides the first direct evidence of ribose in space and the delivery of the sugar to Earth. The extraterrestrial sugar might have contributed to the formation of RNA on the prebiotic Earth which possibly led to the origin of life.”
The team found ribose and other bio-essential sugars including arabinose and xylose in two different meteorites: NWA 801 and Murchison. Ribose is an important component of RNA (ribonucleic acid) which serves as a messenger molecule in building specific proteins needed to carry out life processes.
“It is remarkable that a molecule as fragile as ribose could be detected in such ancient material,” said Jason Dworkin, a co-author of the study at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. “These results will help guide our analyses of pristine samples from primitive asteroids Ryugu and Bennu, to be returned by the Japan Aerospace Exploration Agency’s Hayabusa2 and NASA’s OSIRIS-REx spacecraft.”
Did RNA evolve first?
Scientists so far have been unable to explain how biology could have arisen from non-biological chemical processes. Now, researchers are speculating that RNA may have evolved first only to be later replaced by DNA.
RNA molecules have capabilities that are not found in DNA such as the ability to copy themselves without assistance from other molecules. The new findings could indicate that RNA may have been responsible for coordinating the machinery of life before DNA.
“The sugar in DNA (2-deoxyribose) was not detected in any of the meteorites analyzed in this study,” said Danny Glavin, a co-author of the study at NASA Goddard. “This is important since there could have been a delivery bias of extraterrestrial ribose to the early Earth which is consistent with the hypothesis that RNA evolved first.”
The study is published in the Proceedings of the National Academy of Sciences.