I am currently using computational methods to study the yeast pheromone signaling system. In particular, I am studying the gradient sensing and polarization strategy. The two types, or sexes, of yeast cells (‘a’ and ‘alpha’) emit pheromone molecules which the opposite sex is able to detect. Upon detection, the yeast cell can grow or move in the direction of highest pheromone concentration; naturally, this strategy brings the cell closer to its potential mate. The strategy by which the yeast cell polarizes (or establishes a “front” side) is not yet fully understood. Further intriguing is the fact that the number of receptors that are activated may be within the noise. Out of roughly 8000 uniformly distributed receptors on the cell’s surface, about 80 are activated (bound to pheromone). One potential strategy is for the cell to randomly polarize and perform a random walk-style search for the correct direction. Another strategy could be to wait for more pheromone to bind before polarizing (assuming the side of cell facing the mate will bind more pheromone). To study this problem, I am developing a particle simulator to determine how sharp a gradient across the yeast cell can be and which of these two (or other) strategies is more efficient.