Scientists in Maryland today said they had built from scratch an entire microbial chromosome, a loop of synthetic DNA carrying all the instructions that a simple cell needs to live and reproduce.
The feat marks the first time that anyone has made such a large strand of hereditary material from off-the-shelf chemical ingredients. Previous efforts had yielded DNA strands less than one-twentieth the size, and those pieces lacked many of the key biological programs that tell a cell how to stay alive.
On the basis of earlier experiments, the researchers believe the new, full-length loop would spontaneously "boot up" inside a cell, just as a downloaded operating system can awaken a computer -- a potentially historic event that would amount to the creation of the first truly artificial life form.
