In The Case of Gene Regulation in Cells, students learn how systems biologists are interested in understanding how the presence and absence of different molecules affect protein synthesis. In this lesson, students will learn about gene regulation in cells and then apply this knowledge by identifying analogous parts and processes in a given model—a city, factory, ecosystem, or other system. At the end of the lesson, students should be able to articulate how their model is analogous to gene regulation in cells and its relationship to systems biology: understanding cells as a functioning system can help us understand how systems work in general (e.g. the functioning of a whole ecosystem). This lesson can be used as a concluding activity during a DNA and protein synthesis unit.