| SPECIES | SPECIAL FEATURES | HABITAT | GENOME SIZE (1000s OF NUCLEOTIDE PAIRS PER HAPLOID GENOME) | NUMBER OF GENES (PROTEINS) |
|---|---|---|---|---|
| EUBACTERIA | ||||
| Mycoplasma genitalium | smallest genome of any known cell | human genital tract | 580 | 468 |
| Synechocystis sp. | photosynthetic, oxygen- generating (cyanobacterium) | lakes and streams | 3573 | 3168 |
| Escherichia coli | laboratory favorite | human gut | 4639 | 4289 |
| Helicobacter pylori | causes stomach ulcers and predisposes to stomach cancer | human stomach | 1667 | 1590 |
| Bacillus subtilis | bacterium | soil | 4214 | 4099 |
| Aquifex aeolicus | lithotrophic; lives at high temperatures | hydrothermal vents | 1551 | 1544 |
| Mycobacterium tuberculosis | causes tuberculosis | human tissues | 4447 | 4402 |
| Treponema pallidum | spirochaete; causes syphilis | human tissues | 1138 | 1041 |
| Rickettsia prowazekii | bacterium most closely related to mitochondria; causes typhus | lice and humans (intracellular parasite) | 1111 | 834 |
| Thermotoga maritima | organotrophic; lives at high temperatures | hydrothermal vents | 1860 | 1877 |
| ARCHAEA | ||||
| Methanococcus jannaschii | lithotrophic, anaerobic, methane-producing | hydrothermal vents | 1664 | 1750 |
| Archaeoglobus fulgidus | lithotrophic or organotrophic, anaerobic, sulfate-reducing | hydrothermal vents | 2178 | 2493 |
| Aeropyrum pernix | aerobic, organotrophic hot-steam vents | coastal volcanic | 669 | 2620 |
| EUCARYOTES | ||||
| Saccharomyces cerevisiae (budding yeast) | minimal model eucaryote | grape skins, beer | 12,069 | ~6300 |
| Arabidopsis thaliana (wall cress) | model organism for flowering plants | soil and air | ~142,000 | ~26,000 |
| Caenorhabditis elegans (nematode worm) | simple animal with perfectly predictable development | soil | ~97,000 | ~19,000 |
| Drosophila melanogaster (fruit fly) | key to the genetics of animal development | rotting fruit | ~137,000 | ~14,000 |
| Homo sapiens (human) | most intensively studied mammal | houses | ~3,200,000 | ~30,000 |
From: The Diversity of Genomes and the Tree of Life
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