What is a cell?
![7,0 Medical 3d illustration - conceptual human cells](https://www.yourgenome.org/wp-content/uploads/2023/10/70-Medical-3d-illustration-conceptual-human-cells-1920x1440.jpg)
All living things are made of cells. They are the basic building blocks of life. The human body is composed of trillions of cells, all with their own specialised function.
- Cells are the basic structures of all living organisms.
- Different cells have different functions – such as taking in nutrients from food, providing structure for the body, or fighting infection.
- Cells can group together to form tissues. In turn, tissues group together to form organs, such as the heart and brain.
Inside the cell
- Most cells contain functional structures called organelles. They carry out important tasks like making proteins, processing chemicals and generating energy.
- At the centre of the cell is the nucleus, which acts as the ‘control room’ and coordinates the cell’s activities.
- The nucleus also stores the genome. This holds the genetic instructions that a cell needs to carry out its function.
![](https://www.yourgenome.org/wp-content/uploads/2023/10/71-Cell-Illustration-2015.png)
Illustration showing the structures of an animal cell. Image credit: Laura Olivares Boldú / Wellcome Connecting Science
Different forms of life have different types of cells
![](https://www.yourgenome.org/wp-content/uploads/2023/11/B3-Misc_pollen_colorized_square-768x768.jpg)
All living things are made up of cells
But different forms of life – such as animals, plants and bacteria – have different types of cells.
![](https://www.yourgenome.org/wp-content/uploads/2023/11/B4-Rhizomnium_punctatum_lamina_square-768x768.jpg)
Since animals and plants have very different lives, their cells need to be different in several ways.
For example, plant cells have a special cell wall, which makes them very rigid and able to draw water up from the soil.
![](https://www.yourgenome.org/wp-content/uploads/2023/11/B5-national-cancer-institute-L7en7Lb-Ovc-unsplash_square-768x768.jpg)
Animals and plants are called multicellular organisms.
This is because they are made up of many cells.
![](https://www.yourgenome.org/wp-content/uploads/2023/11/B6-Bacteria_259_04_Airborne_microbes_square-768x768.jpg)
Bacterial cells are very different to animal and plant cells.
For example, their DNA is not stored in a nucleus – instead it floats inside the cell. Bacteria are single-celled organisms, known as unicellular.