Cell analogies: every part of a cell, in a city

Teachers and students love the cell-as-a-city analogy because every organelle has a job a city also needs doing. This guide lists each part of a cell, what it really does, and the city comparison that fits it best, with a link to our funny relatable for each.

Part of the cell	What it really does	In a city	Our analogy
The cell membrane	A thin, flexible layer that controls what goes in and out of the cell.	The border: checkpoints and customs deciding who and what gets through.	As a nightclub door
The cell wall (plant cells only)	A rigid outer layer that gives the cell its shape and strength. It lets almost everything through, so it is not the gatekeeper.	The city wall.	As a castle wall
The cytoplasm	The jelly-like fluid inside the cell, where many reactions happen and the organelles sit.	The ground, streets and air of the city, where everything else is placed.	As trifle jelly
The nucleus	Holds the DNA and controls what the cell does.	Town hall: the council offices that keep the plans for the whole city.	As a head teacher
The nucleolus	A dense spot inside the nucleus that makes the parts of ribosomes.	The tool-making workshop that supplies the factories.	As a design and technology workshop
The mitochondria	Release energy from food in a form the cell can use (ATP).	The power station.	As a power station
The ribosomes	Build proteins by following the instructions copied from the DNA.	The factory workers who build the products.	As kitchen staff
The endoplasmic reticulum	A network of folded membranes that makes and moves proteins and fats.	The road and rail network, carrying goods around the city.	As a conveyor belt
The Golgi apparatus	Sorts, packages and labels proteins so they reach the right place.	The sorting office and post depot.	As a sorting office
The lysosomes	Break down waste and worn-out parts using enzymes.	The recycling centre and the bin lorries.	As a bin lorry
The peroxisomes	Break down fatty acids and neutralise harmful chemicals.	The hazardous waste team.	As a hazmat team
The vacuole	Stores water and nutrients. Plant cells have one large permanent vacuole.	The water tower and the warehouses.	As a loft water tank
The chloroplasts (plant cells only)	Capture sunlight to make sugar, in photosynthesis.	The solar farm.	As a solar farm
The cytoskeleton	A network of protein fibres that gives shape, holds parts in place and acts as tracks.	The scaffolding and the tram lines.	As scaffolding on a building site
The centrosome	Organises the fibres that pull the copied chromosomes apart when a cell divides.	The traffic controller who organises the move when the city splits in two.	As a rowing cox

Where the city analogy breaks down

Every analogy simplifies, and this one is no exception. A city has a mayor and a council that make decisions. A cell has no one in charge: the nucleus holds the instructions, but the cell’s parts respond to chemical signals, not orders. A city is built by people from outside it, while a cell makes all of its own parts, and then copies the whole lot when it divides. And a city’s buildings are fixed, where a cell’s membranes and fibres are constantly being built, moved and taken apart.

Is the “powerhouse of the cell” analogy wrong?

Partly. Mitochondria do not create energy, because energy cannot be created. They transform the energy stored in food molecules into ATP, the form of energy the cell can spend. They also do other jobs, such as storing calcium, making heat and helping decide when a cell should die. “Power station” is a good first picture, but it is not the whole story.

Plant cells and animal cells

Both have a nucleus, cytoplasm, cell membrane, mitochondria and ribosomes. Plant cells also have a cell wall, chloroplasts and a large permanent vacuole, which is why they keep a fixed, regular shape. Animal cells lack those, are usually more flexible and get their energy from food. See animal cells and plant cells as a tent and a log cabin.

More ways to picture a cell

Cell biology explained, with analogies: every relatable on this page, in a sensible reading order.
A cell is like a city: the whole cell in one relatable.
For teachers: Serious and Like I’m five versions for the classroom.

Relatables are written by an AI and checked by a person, but an analogy always simplifies. Check anything you plan to teach against your specification.