21.   The next question was, What does this gene do?

22.   The next task is to decipher exactly what those genes do, how they interact, and how they are regulated in the body.

23.   The task of the post-genome era is to figure out what each gene does and how it is controlled.

24.   To learn what a gene does in yeast cells, molecular biologists simply delete it and watch to see how the cell functions without it.

25.   Whatever the mouse genes do, the researchers said they would expect corresponding genes to exist in people, though probably not on the same chromosomes.

26.   While it is not yet known how the genetic change prolongs life, the scientists say they know what the gene does -- it is involved in metabolism.

27.   It relies on statistical analysis and landmarks along chromosomes to zero in on target genes, without any prior knowledge about what the genes normally do.

28.   Scientists have not yet determined what the newfound gene does when it is normal or when it is defective.

29.   That will enable scientists to start work on the next and potentially lucrative step -- finding out what each gene does.

30.   The next task will be learning what all these genes do.