Quick facts
Bacteria are prokaryotes: DNA is not wrapped in a nucleus, ribosomes make protein, and many species build a peptidoglycan wall that Gram stain still uses as a first map.
They invented photosynthesis, nitrogen fixation and fermentation long before animals existed. Most lineages never infect a human; a minority of specialists cause famous diseases.
This atlas treats bacteria as a tree of life, not a synonym for 'germ'. Beneficial, environmental and pathogenic stories sit in later topics.
The profile
- Familiarity95
- Medical weight72
- Benefit78
- Risk55
- Research90
- Live debate30
Risk
Single-celled prokaryotes with cell walls ? the oldest widespread life form, and both partners and pathogens.
Seven ways into this topic
Frequently asked questions
Are bacteria the same as archaea?
Does Gram-positive mean more dangerous?
Can bacteria live without oxygen?
Why won't most species grow on a lab plate?
Do antibiotics kill all bacteria?
Are bacteria animals or plants?
How fast can they divide?
Is this medical advice?
Sources & research
More in Tree of microbes
Viruses
Packets of DNA or RNA that are not cells — they replicate only inside living hosts.
Familiarity 96Fungi
A eukaryotic kingdom of yeasts, moulds and mushrooms — chitin walls, external digestion, partners of plants.
Familiarity 80Archaea
A prokaryotic domain that is not bacteria — methanogens, extremophiles and no known human pathogens.
Familiarity 35Bacteriophages
Viruses that infect bacteria — Earth's most abundant biological entities, and a concept-level idea in medicine.
Familiarity 42Protozoa
Motile unicellular eukaryotes — a teaching grade that includes pond ciliates and a minority of serious parasites.
Familiarity 58