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
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16 June 2021
A turtle’s life
Sea turtles are the oldest living reptiles today. They have been inhabiting the oceans for over 150 million years without…
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29 April 2021
Etruscan shrews, ferocity in miniature
Which is the tiniest micromammal, i.e. the smallest mammal on the planet? Up until almost half a century ago, it…
10 March 2021
International Year of Fruits and Vegetables 2021
This year has been designated by FAO (Food and Agriculture Organisation of the United Nations) as the International Year of…
8 March 2021
8 March. We remember Rosalind Franklin, the great female DNA scientist.
DNA was first isolated by Friedrich Miescher, a Swiss biochemist in 1869. It was a brilliant, but not complicated operation:…
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27 February 2021
In search of the riders of icebergs
International Polar Bear Day, set up by Polar Bears International, a non-profit organisation, was held on 27 February. The aim…
8 January 2021
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Some people call them "monkeys with feathers" because they can do clever things comparable to many of our monkey cousins.…
18 December 2020
The Christmas Star Tradition
Let's discover together stories and legends about the Christmas Star...
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16 June 2021
A turtle’s life
Sea turtles are the oldest living reptiles today. They have been inhabiting the oceans for over 150 million years without…
29 April 2021
Etruscan shrews, ferocity in miniature
Which is the tiniest micromammal, i.e. the smallest mammal on the planet? Up until almost half a century ago, it…
-
10 March 2021
International Year of Fruits and Vegetables 2021
This year has been designated by FAO (Food and Agriculture Organisation of the United Nations) as the International Year of…
8 March 2021
8 March. We remember Rosalind Franklin, the great female DNA scientist.
DNA was first isolated by Friedrich Miescher, a Swiss biochemist in 1869. It was a brilliant, but not complicated operation:…
-
16 June 2021
A turtle’s life
Sea turtles are the oldest living reptiles today. They have been inhabiting the oceans for over 150 million years without…
From the Multimedia section
Facts
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Bio-luminescence
Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...
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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...
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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 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...
-
Bio-luminescence
Many sea animals, including a lot of fish and molluscs that live in the dark in the ocean depths...