Bacteria are everywhere. Only a few micrometers in length and having a wide range of shapes, from spheres to rods to spiral, bacteria are the huddled masses of the microbial world, performing tasks that include everything from causing disease to fixing nitrogen in the soil.

Figure 3.18: A basic illustration of a bacteria. Image from URL:

Figure 3.18: A basic illustration of a bacteria.
Image from URL:

Humans need bacteria. In fact, there are approximately ten times as many bacterial cells in the human body as there are human cells. The vast majority of the bacteria in the body are rendered harmless by the protective effects of the immune system, and a few are beneficial. However, a few species of bacteria are pathogenic and cause infectious diseases.

In the modern world, antibiotics are used to treat bacterial infections and in agriculture, so antibiotic resistance is becoming common. In industry, bacteria are important in sewage treatment, the production of some kinds of foods, biotechnology, the manufacture of antibiotics and other chemicals, and much more.

Once regarded as plants, bacteria are now classified as prokaryotes. Unlike cells of animals and other eukaryotes, bacterial cells do not contain a nucleus. Although the term bacteria traditionally included all prokaryotes, the scientific classification changed after the discovery in the 1990s that prokaryotes consist of two very different groups of organisms that evolved independently from an ancient common ancestor; we will explore this distinction in greater detail in the next few pages.

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The MSP project is funded by an ESEA, Title II Part B Mathematics and Science Partnership Grant through the Montana Office of Public Instruction. MSP was developed by the Clark Fork Watershed Education Program and faculty from Montana Tech of The University of Montana and Montana State University, with support from other Montana University System Faculty.