Story of Discovery: DNA Chips
By Karen Hopkin

It's the spring of 2020, and your grades have taken a nose dive. You just can't seem to concentrate on the books-at home, your kid sister is driving you nuts, and at school, you're having serious daydreams about your lab partner. So when your mom throws a fit about your "poor academic performance," she drags you down to the doctor for a DNA check. One drop of blood, and five minutes later, the results are in: Your door-slamming, eye-rolling, class-cutting, and body-piercing genes are all turned on; your yessir-ing, exam-acing, supper-table-clearing, and get-to-bed-by-8:30 genes are completely shut down. Diagnosis: puberty.

Okay, so that's a bit far-fetched-body piercing is probably controlled by a whole bunch of genes. But the idea that you can learn everything about anybody's genetic makeup quickly and easily is fast becoming a reality, thanks to DNA chips.

These chips, also known as DNA microarrays, are made of a silicon or glass plate studded with DNA fragments. Smaller than a postage stamp, DNA chips will someday make it possible to identify and analyze every one of your genes in an afternoon. A trip to the doctor's office, for example, may involve a quick check of a few critical genes to determine whether you'll react well or poorly to a drug, which kind of bug you've caught, or whether you're likely to develop heart disease, cancer, or Alzheimer's.

These powerful gene screens spring from the marriage of two technologies: techniques for slicing, dicing, and sequencing DNA and the miniaturization that reduced 30-ton mainframe computers to something you can carry in one hand. DNA chips come in a variety of flavors, with different substrates, different DNAs, different methods of preparation. But they all exploit the fact that every single strand of DNA will bind tightly to its perfect partner, its complementary strand. So DNA fragments anchored to a chip will latch onto their partners if the partners are present in a solution sloshed over the chip surface. Because you know the sequence of DNA stuck to the chip at each particular spot, you know that the sequence that will stick to that spot (see Research in the News for details).

In some sense, we are our genes. By offering a way to examine our genes-and the genes of other organisms-DNA chips stand to help us understand, at the most fundamental level, how cells work. And what it is that makes you, well, you. Which is remarkable, considering that 50 years ago, scientists had no idea what DNA even looked like, much less how it worked.

To follow the twisty, turny pathway that led to DNA chips, wind your way through this story of discovery

On The Web
Access Excellence, an educational project, has a nice timeline on the development of biotechnology. http://www.accessexcellence.org/AB/BC/1977-Present. html