A city border is like a cell membrane because it protects the people inside it, like the membrane protects the cell. People at a city border control what comes in and out of the city, like a cell membrane controls what comes in and out of a cell.

Cytoplasm is like a city because a city contains all of the things that make up the city, like cytoplasm contains the organelles, or DNA, of a cell.

A city hall is like a nucleus because the city hall and the people in it control the city, like the nucleus controls the cell. It also is usually the first building created in a city,the foundation of it, like a nucleus contains the cell's DNA, the foundation of the cell.

A cytoskeleton is like the foundation of buildings because it upholds the building and it's structure and shape, like a cytoskeleton does to a cell. It also helps keep the house from moving, like a cytoskeleton controls the cell movement.

An exterminator functions like smooth ER because it removes toxins and rids of poison after it kills the rats, like the smooth ER removes toxins from a cell and rids poison from the cell. Exterminators also produce safety and contentness of the people they remove the rats from, like the smooth ER produces lipids, which are good for the cell.

A factory is like a rough ER because it makes foods, some of which contain proteins for the city, like the rough ER makes proteins for the cell.

Ribosomes create proteins just like the generator creates energy for the city to continue running on power.

The UPS company processes, sorts, and delivers mail throughout the city, like the Golgi apparatus does that to proteins.

An access bus is like a vesicle because it transports older people to where ever they need to go in the city, like a vesicle transports macromolecules throughout a cell.

Solar panels supply energy to the city and houses inside the city, like a mitochondria supplies energy to the cell.

Storage units are like a vacuole because they store the things people in a city would need, like the vacuole stores things the cell would need.

Police are liked lysosomes because they protect the cell from invaders and break down worn parts of the city, like old buildings, as lysosomes break down worn out parts of the cell and defend the cell from invading viruses or bacteria.

An army is like a cell wall because the can surround the city in times of danger and protect it, like a cell wall surrounds a cell and protects it.

Restaurants is like chloroplast because it creates food for the people, like chloroplast creates sugar and food for plant cells.