I'm going to tell you the 3 parts of cell theory to give you idea for your narrative
There are 3 part of the cells :
- Cell Membrane = the one that control the in and outs of cells
- Cytoplasm = a place where almost all activities in cells happen
- Nucleus = The one that give orders for the overall cell activities
If converted it to a city , Nucleus would be the central government , or the decision maker such as the mayor.
The cell membrane would be the one that guard the city at the border , and the cytoplasm would be the executive branch of the city
hope this helps