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Biological Environment > Bacteria |
This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. |
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The first cells appeared on Earth about 3.5 billion years ago. These early cells were very similar to the simplest cells we find on Earth today, called bacteria (sometimes called germs). Note that one of these is called a bacterium. Later bacteria evolved many new features. For example bacteria could swim. They used a long twisted whip-like tail called a flagellum fixed to a wonderful tiny rotating motor. This made the flagellum twist round and so pushed or pulled the bacterium along!
Bacteria have only one cell each. They can be round (coccus), rodlike (bacillus), or curved (vibrio, spirillum, or spirochete). Bacteria live almost everywhere on Earth, including the soil, water, organic matter, and the bodies of multicellular animals (eukaryotes). Some bacteria benefit humans and other plants and animals. Others are harmful; bacteria are the chief cause of infectious diseases in humans. Bacteria differ from more advanced cells such of those found in animals and plants because they have no membrane around their nucleus nor any organelles. Simple cells like this are called prokaryotes. Bacteria make up the group which biologists call monera. Archaebacteria are probably living fossils, similar to the earliest bacteria. |
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Biological Environment > Bacteria |
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Basic Information |
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