Leigh now believes that tiny molecular versions of the Turing machine could assemble what we struggle to build in the organic realm, like new drugs and plastics with traits so enhanced and precise that they’re out of reach for current tools.“It's absolutely clear that it's possible,” he says, “because there already is this working example called biology.” Nature has given every life-form its version of the Turing machine: ribosomes, cellular structures that slide down sequences of mRNA to churn out proteins one amino acid at a time.His team designed a ring-like “ratchet” molecule in 2007 that was powered by light and could move forward along a molecular track.The surrounding liquid's pH changes as the acid decomposes, triggering the track molecule to usher the head molecule forward one step—and never backward.As the head moved along the tape, it would contort into a predictable shape each time it scanned a specific block of information."