Bacteria are microscopic single-celled organisms that inhabit virtually all environments on Earth, including the bodies of multicellular animals. Bacteria lack a membrane-bound nucleus and other internal structures.

Bacteria are microscopic living organisms that have only one cell. The word for just one is “bacterium.” Millions (if not billions) of different types of bacteria can be found all over the world, including in your body.

Learn about bacteria, the oldest and simplest forms of life on earth. Find out their features, types, uses, and harmful effects with diagrams and examples.

Learn about the characteristics, parts, and types of bacteria, the simplest and most diverse form of life on earth. Find out how bacteria reproduce, grow, and cause diseases with diagrams and examples.

Classification of bacteria: Bacteria belong to Kingdom Monera, together with Cyanobacteria (blue-green algae), which are also prokaryotic. Bacteria may be classified based on their shape: spherical (cocci), rod-like (bacilli), spiral ( spirochetes and spirilla), or comma-shaped ( vibrios ).

What are Bacteria? Bacteria are microbes with a much simpler cell structure than many other organisms, but they are by no means simple. The more scientists look, the more they understand about how complex bacteria are.

Bacteria are single-celled microorganisms that lack a nuclear membrane, are metabolically active and divide by binary fission. Medically they are a major cause of disease. Superficially, bacteria appear to be relatively simple forms of life; in fact, they are sophisticated and highly adaptable.

Students of Pasteur, Koch, and others discovered in rapid succession a host of bacteria capable of causing specific diseases (pathogens). They also elaborated an extensive arsenal of techniques and laboratory procedures for revealing the ubiquity, diversity , and abilities of microbes.

bacteria, Group of microscopic, single-celled organisms that inhabit virtually all environments, including soil, water, organic matter, and the bodies of multicellular animals.