By Rick Weiss
Washington Post Staff Writer
It has been 50 years since scientists first created DNA in a test tube, stitching ordinary chemical ingredients together to make life's most extraordinary molecule. Until recently, however, even the most sophisticated laboratories could make only small snippets of DNA -- an extra gene or two to be inserted into corn plants, for example, to help the plants ward off insects or tolerate drought.
Now researchers are poised to cross a dramatic barrier: the creation of life forms driven by completely artificial DNA.
Scientists in Maryland have already built the world's first entirely handcrafted chromosome -- a large looping strand of DNA made from scratch in a laboratory, containing all the instructions a microbe needs to live and reproduce.
In the coming year, they hope to transplant it into a cell, where it is expected to "boot itself up," like software downloaded from the Internet, and cajole the waiting cell to do its bidding. And while the first synthetic chromosome is a plagiarized version of a natural one, others that code for life forms that have never existed before are already under construction.
The cobbling together of life from synthetic DNA, scientists and philosophers agree, will be a watershed event, blurring the line between biological and artificial -- and forcing a rethinking of what it means for a thing to be alive.