Bacteria — everywhere at once

The organisms of Domain Bacteria are made of prokaryotic cells as well. But unlike the archaea, they can be destroyed by antibiotics.

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Figure 13.4 — organisms of Domain Bacteria: bacteria and cyanobacteria (blue-green algae).

They are the abundant group, found in every environment on Earth. Some act as disease-causing agents. Organisms such as bacteria and cyanobacteria (blue-green algae) belong here.

Inside a bacterial cell

Prokaryotic does not mean there is no nucleus — it means the nuclear material is not separated off by a membrane. It sits in the cytoplasm itself.

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Figure 13.5 — the electron microscope structure of a bacterial cell: flagellum, capsule, cell wall, cell membrane, pili, ribosomes, nuclear material and plasmid DNA.

Archaea or bacteria?

Both being prokaryotic, they are easy to confuse. The easiest way to hold the difference is antibiotics: bacteria are caught by them, archaea are not.