A common biochemical may help forge a missing link in a popular but unproven theory about how life got started.
One of the leading ideas of how loose molecules evolved to become complex cells begins with the hereditary molecule ribonucleic acid. Modern cells use RNA to make proteins, the workhorses of cellular function, but RNA likely preceded both proteins and DNA.
Evolution relies on reproduction, so any RNA-based origin-of-life theory has to include a way for RNA to copy itself. In previous work, biologist Jack Szostak of Harvard Medical School and colleagues showed that primitive RNA replication happens best when contained inside protocells. These containers have porous walls made of simple fat molecules — a far cry from modern cells, with their nearly impenetrable walls and sophisticated intake and excretion mechanisms.
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