The Green Fluorescent Protein

In the 90s, there was this incredible transformation in biology because of the cloning of the green fluorescent protein. So now you could look at things that are going on in the cell without having to kill the cell or grow up a huge population of cells. What we did is we took three of the best characterized repressor genes and we kind of engineered them into this three protein circuit. And then we put in this green fluorescent protein and had one of the three proteins controlling it. The idea is that if the oscillations are going on inside the cell and we make a movie of the cells, then you can just look at the cells and you'll see them get brighter and dimmer over time