In January, students at M.I.T. are let off the leash to follow their fancies. The annual monthlong Independent Activities Period is a playground for the mind, offering courses, seminars, and special events devoted to everything from energy-dispersive x-ray spectroscopy to poetry reading. There's glassblowing, building spacecraft for mice, and the all-important coolest-stuff-made-of-duct-tape competition. "I wish I didn't teach an IAP," says Drew Endy, an assistant professor in biological engineering. "I'd take a whole bunch of the courses."
But Endy does teach an IAP. This year his class is devoted to building counters - devices that count from, say, 1 to 32. That may not sound like much of a challenge for students at the world's most prestigious engineering school; in fact, it's the sort of thing a nerdy middle school kid would solder together. But here's the rub: The counters his students design won't be electronic, but biological. They won't be made of transistors, but DNA. And they won't be inserted into breadboards, but living bacteria.
While Endy is keen on counters at the moment (they might have practical uses; for example, indicating how many times a given cell has divided since the counter was last reset), they're just stepping-stones to a new era in biology. Last year, his students programmed bacteria to form polka-dotted colonies. The year before, they designed microorganisms that blinked like Christmas lights. But the real purpose of the course isn't making a particular biological circuit; it's figuring out what it takes to make any biological circuit.