What Is a Cell?
The cell is the smallest structural and functional unit of all living things. Just as a house is made of bricks, living organisms are made of cells.
Types of Cells
| Feature | Plant Cell | Animal Cell |
|---|---|---|
| Cell wall | Present | Absent |
| Chloroplast | Present | Absent |
| Large vacuole | Present | Small or absent |
| Shape | Regular (rectangular) | Irregular |
| Centrioles | Absent | Present |
Parts of a Cell and Their Functions
- Nucleus: Controls all cell activities (the "brain")
- Cell membrane: Controls what enters and leaves the cell
- Cytoplasm: Jelly-like fluid holding organelles in place
- Mitochondria: Produces energy (powerhouse of the cell)
- Ribosome: Makes proteins
- Chloroplast: (Plant only) — captures sunlight for photosynthesis
- Vacuole: Stores water, food, and waste
💡 All living things are made of cells. Some organisms (like bacteria) have just one cell — they are called unicellular. Humans have trillions of cells — we are multicellular.