With a precise motion, Li Ma, a technician at the J. Craig Venter Institute in Rockville, MD, pipettes a cherry-red solution of bacterial cells into a vial that contains a clear solution of fragile DNA loops. These loops, the largest pieces of DNA ever assembled in the lab, are each capable of controlling all the ordinary functions of a cell. But the DNA didn't originate in any bacteria: instead, scientists pieced it together from bottled chemicals. The process they recently developed for doing this is the first to yield synthetic cells that are capable of surviving. Some of the bacterial cells that Ma is working with will fuse together in the solution, engulfing the synthetic genome and then replicating and living under its control.

Conventional genetic engineering is a lengthy process in which genes are altered one by one, often over successive generations of organisms. That makes radically changing a genome a daunting proposition. But the newly developed techniques allow researchers to edit genomes on a computer, subtracting or adding genes by literally cutting and pasting them in a file. It's more like word processing than the traditional lab work involved in culturing and screening generations of organisms. The researchers can then perform the genetic equivalent of printing out the file, at which point they're able to transplant the result--a new genome--into existing cells. These steps dramatically speed up the engineering process; it might take just weeks to complete experiments that previously would have taken months or years.