Human Genetics

Bacterial Genome Sizes vary widely across species, but they are generally smaller than those of eukaryotes. Most bacterial genomes range from 500,000 to 10 million base pairs (0.5 to 10 megabases), containing between 500 and several thousand genes. For instance, Escherichia coli, a commonly studied bacterium, has a genome of approximately 4.6 million base pairs, encoding around 4,300 genes. In contrast, Mycoplasma genitalium has a much smaller genome of about 580,000 base pairs with around 480 genes. The compact nature of bacterial genomes reflects their efficiency, with fewer non-coding regions compared to eukaryotic genomes.