Some genes in our genome act as switches, turning other genes on or off at different times and for different lengths of time. In an animal's embryonic stage, these gene switches play a predominant role in laying out the animal's basic body plan and perform other early functions. In this slide show, you'll see a striking example–in that lab standard Drosophila melanogaster, the fruit fly–of just how powerful these embryonic gene switches can be.

Nipam Patel is a professor in the Departments of Molecular and Cell Biology and Integrative Biology at UC Berkeley and runs a research laboratory that studies the role, during embryonic development, of homeotic genes (the genetic switches described in this slide show).