Biology

Bacteria or prokaryotes are the most common living beings on Earth: one spoonful of soil can contain, for instance, up to 10,000 billion bacteria. They are unicellular organisms, i.e. they consist of one cell only. They are very small in size, since a large part of bacterial cells have a diameter of 1 to 10 microns (one micron equals one thousandth of a millimetre), so an orderly row of one thousand bacteria would be just one millimetre long. Bacterial cells, unlike the cells of superior organisms (eukaryotes), do not have organelles enwrapped in membranes (nucleus, Golgi apparatus…) or chromosomes. Chromosomes are structures made of DNA wrapped around proteins, called histones, and their purpose is to make the long DNA molecules contained in the nucleus more compact and orderly.
Chromosomes are essential since they arrange the large amount of genetic material contained in eukaryote cells: if, for instance, the DNA contained in just one human somatic cell were unwrapped, the resulting molecule would be approximately two metres long! In bacteria, instead, the DNA is not contained in a nucleus and is round in shape. Another specific feature of bacteria is their protective structure (the wall) that enwraps and encloses the whole cell. The cellular wall is composed of proteins and sugars and, as well as protecting the micro-organism, it puts the cell in contact with the external environment and the other bacterial cells.

Special reports

From the Multimedia section

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  • life

    A zoo in a drop

    Look
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    Intestinal bacteria

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    Micro-organisms in gastrointestinal

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Facts

  • Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

    Bacteria as detergents

    Enzymes are proteins produced by the cells of all living organisms...

    Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...

  • Bacteria as Sherlock Holmes

    A drop of blood, a fragment of skin or a hair found on the scene of a crime can supply…

    Down-pouring bacteria

    It sounds incredible, but recent researches have found that bacteria can cause some atmospheric phenomena...

    High-fashion bacteria

    Some bacteria, the Clostridia, were used to make textile fibres...

  • Let’s eat!

    The economic importance of fungi is increased by the “edible” mushrooms...

    Predator mushroom

    <em>Pleutrotus ostreatus</em> mushroom does not have teeth or claws but it is...

    Decomposing organisms

    The ability to destroy organic matter has been used by man...

  • 13 May 2011

    Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

    Bacteria as detergents

    Enzymes are proteins produced by the cells of all living organisms...

  • Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...

    Bacteria as Sherlock Holmes

    A drop of blood, a fragment of skin or a hair found on the scene of a crime can supply…

  • Down-pouring bacteria

    It sounds incredible, but recent researches have found that bacteria can cause some atmospheric phenomena...

    High-fashion bacteria

    Some bacteria, the Clostridia, were used to make textile fibres...

  • Bio-luminescence

    Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...

  • Bacteria as detergents

    Enzymes are proteins produced by the cells of all living organisms...

  • Bacteria as miners

    The ability of chemoautotrophic bacteria to take energy from...