Science
What is Cell?
A cell is the smallest unit of life — the basic building block that makes up every living thing, from bacteria to blue whales. Some organisms are a single cell; humans are made of tens of trillions of them, each running the chemistry that keeps us alive.
See it, don’t just read it.
Watch a 2-minute lesson with voice + animation that explains cell.
Key things to understand
- 1All living things are made of one or more cells — a core idea of biology.
- 2Cells contain a watery interior (cytoplasm), genetic instructions (DNA), and tiny structures called organelles that do specific jobs.
- 3There are two broad types: simple prokaryotic cells (like bacteria) and complex eukaryotic cells (like plant and animal cells) that have a nucleus.
- 4Cells copy themselves by dividing, which is how bodies grow and repair.
- 5Specialized cells do different jobs — nerve cells carry signals, muscle cells contract, red blood cells carry oxygen.
Frequently asked questions
- What are the main parts of a cell?
- Most cells have a membrane (outer boundary), cytoplasm (the interior), DNA (instructions), and organelles such as mitochondria that power the cell.
- What's the difference between plant and animal cells?
- Plant cells have a rigid cell wall and chloroplasts for photosynthesis; animal cells have neither — but both share a nucleus, a membrane, and mitochondria.
- How many cells are in the human body?
- Estimates put it around 30–40 trillion cells, not counting the trillions of bacteria that live in and on us.