Bacteria β Invisible Inhabitants of Earth
Discovering the tiniest living things on our planet
π Quick Recall
You already know that all living things are made of cells, and that we use microscopes to see very small objects. You've also learned about the Kingdoms of Life β plants, animals, and fungi. Today we meet a completely different group of living things: Bacteria!
π¬ What Are Bacteria?
Bacteria (singular: bacterium) are single-celled organisms β living things made of just one cell. They are a type of microorganism (also called a microbe), meaning they are too small to see without magnification.
What makes bacteria truly special is their cell structure. Remember how plant and animal cells have a nucleus β the "control centre" that holds DNA? Bacteria do NOT have a nucleus. Their DNA floats freely inside the cell. Scientists call organisms without a nucleus prokaryotes (pro-CARRY-oats).
| Feature | Bacteria Cell | Plant / Animal Cell |
|---|---|---|
| Nucleus | β No | β Yes |
| Cell wall | β Yes | Plants β / Animals β |
| Cell membrane | β Yes | β Yes |
| Number of cells | One (unicellular) | Usually many (multicellular) |
| Size | Very tiny (0.5β10 Β΅m) | Much larger (10β100 Β΅m) |
