Although DNA transmits
genetic information through time, it basically has
a passive role.
Proteins encoded by DNA actually
carry out the myriad cellular reactions that constitute
Now that the human Genome project
has provided us with a catalog of tens of thousands
genes, we are left with the question:
"What do proteins made by these
genes actually do?"
Scientist have always looked
to mutant organisms to provide clues about protein
function, Now, specific mutants can be created at
will by inserting an altered or non-functioning
copy of a gene back into a living organism, then
looking for changes in behavior or development.
Since mice breed quickly and share about 99% of
their gene with humans, they have become the animal
model of choice for large-scale functional studies.
However, doing a single transgenic experiment is
several orders of magnitude more difficult than
sequencing the gene itself.
The real work of understanding
the human genome still lies ahead.