What are you made of? What about a plant? What about bacteria? All living things consist of small building blocks. These are called cells. At first glance the cells of bacteria, plants and animals look similar, but if you look closely you will probably see some differences. This is because not all cells have the same components.
For example, chloroplasts are only found in plants. They enable them to engage in ‘photosynthesis’. This means that they produce their own food and oxygen with the help of sunlight.
Using the table below, you can test your teacher, companion or (grand)parent! Do they know, for example, what a flagellum is for?
Cell component | Main function | Bacteria | Plant | Animal |
| Cell wall | Strengthens and protects | Yes | Yes | No |
| Cell membrane | Checks which substances are allowed in and out of the cell | Yes | Yes | Yes |
| Cytoplasm | Cell liquid in which cell parts float | Yes | Yes | Yes |
| DNA | Contains hereditary information | Yes | Yes | Yes |
| Ribosome | Makes proteins | Yes | Yes | Yes |
| Nucleus | Contains DNA and controls the activities in the cell | No | Yes | Yes |
| Mitochondrium | Power station | No | Yes | Yes |
| Endoplasmic reticulum | Contains ribosomes and transports proteins | No | Yes | Yes |
| Golgi apparatus | Processes, stores and transports proteins | No | Yes | Yes |
| Chloroplast | Photosynthesis | No | Yes | No |
| Large vacuole | Stores water and nutrients | No | Yes | No |
| Flagellum | Propulsion | Sometimes | Sometimes | Sometimes |
| Pilus | Bonds to surfaces or transfers DNA | Sometimes | No | No |
Cells in the human body
Do you know how many cells the human body contains? Take a guess.
An adult human being has about 30 to 37.2 trillion cells — or more than 30,000 billion. By comparison, our galaxy ‘only’ has 100 billion stars.