Chlamydomonas are single-celled green algae similar to pond scum. Like plants, Chlamydomonas cells make energy from sunlight. They swim toward light using a pair of whip-like flagella that breaststroke through the water. Swimming direction is determined by a highly organized structure inside the cell called the eyespot. Like human eyes, the eyespot contains molecules that sense light. To form the eyespot, the light sensors assemble with Velcro-like helper proteins at a precise position relative to the flagella. We study the eyespot as a model for understanding how cells establish up, down, left, right, and the 3D location of unique internal compartments. Assembling and placing structures accurately is important for the health of all cells/organisms. To examine how the eyespot forms at the correct location in the cell, we label different proteins with glow-in-the-dark colors and take pictures with a high-powered microscope. The “skeleton” of the cell and the flagella are labeled green. The light-sensing proteins in the eyespot are red. The MLT1 protein, identified in our lab, is blue. MLT1 is a very large protein that helps direct the light-sensing proteins to the eyespot.