The search for life in space just got a little sweeter. In the early solar system, ice grains hit by sunlight may have formed sugar molecules on their surfaces, according to a new experiment. Those sugars include ribose: the backbone of RNA, which is implicated in the origin of life.
All known life makes at least some use of RNA as a genetic material, and as the “R” in RNA, ribose holds up the compounds that encode genetic messages. But it’s been hard to understand how ribose could be made in the absence of living organisms, to be part of a precursor for life.
Other components of living cells, such as amino acids, which are the building blocks of proteins, have shown up in experiments and samples from meteorites for years. So have molecules that resemble cell membranes. If they and ribose had all existed at the same time, it could have set the stage for life to evolve.
But sugars like ribose are hard to come by, since they often stick together in a way that makes them impossible to extract. “Sugars like to react with each other,” says Cornelia Meinert at the University of Nice Sophia Antipolis in France. “In the end, everything is brown like caramel.”
Now Meinert’s team was able to produce ribose by shining ultraviolet light on a frozen blend of water, methanol and ammonia. This mixture represents our solar system in its infancy, before tiny grains of dust and ice collapsed into planets.
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