Colonies of yeast (Saccharomyces cerevisiae) pictured under a microscope. In glucose-rich conditions (left), yeast cells grow in a tight cluster. But when glucose is limited (right), new cells grow outward, forming a filament-like configuration that may aid in the search for food. A new study identifies the cellular mechanisms that cause the change in growth pattern, as well as the amount of time it takes for the shift to occur. Bar, 10 microns.