NEW YORK (AP) — Scientists are working to create custom-made DNA to be inserted into living cells that would change how they function or provide treatments for diseases. The effort could also someday help give scientists the profound and unsettling ability to create entirely new organisms.

Scientists have long been able to make specific changes in the DNA code. Now, they're taking the more radical step of starting over, and building redesigned life forms from scratch.

The cutting edge of this effort is in yeast. New York University researcher Jef Boeke is directing an international team working to "rewrite" the yeast genome, following a detailed plan they published in March.

Some have found the idea of remaking DNA disconcerting, and scientists plan to get guidance from ethicists and the public before they try it.