Bacteria
Bacteria are a large domain of unicellular prokaryotic microorganisms. They are among the oldest and most abundant life forms on Earth and inhabit nearly every environment, from soil and water to extreme habitats and the bodies of plants and animals. Typical bacterial cells are small, usually 0.2 to 5 micrometers in length, and lack a membrane-bound nucleus or other organelles, with a cytoplasmic region bounded by a cytoplasmic membrane and surrounded by a cell wall.
Many bacteria have cell walls containing peptidoglycan, which helps distinguish them from archaea. Based on the
Bacteria reproduce mostly by binary fission, enabling rapid population growth. They also exchange genetic material through
Metabolic diversity is broad; bacteria can be photo-, chemo-, or heterotrophs, and may be aerobic or anaerobic.
Humans interact with bacteria in many ways. Some species are pathogens that cause diseases, while others are