Understanding:
• All organisms are classified into three domains
Currently, all living organisms are classified into three domains:
- Eukarya – eukaryotic organisms that contain a membrane-bound nucleus (includes protist, plants, fungi and animals)
- Archaea – prokaryotic cells lacking a nucleus and consist of the extremophiles (e.g. methanogens, thermophiles, etc.)
- Eubacteria – prokaryotic cells lacking a nucleus and consist of the common pathogenic forms (e.g. E. coli, S. aureus, etc.)
Originally, the two prokaryotic domains were considered only as a single kingdom (Monera), however biochemical differences were discovered between the two groups which warranted their reclassification into separate domains
Three Domains of Life
