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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15 September 2021
Can you be intelligent without a brain?
Can you be intelligent without a brain? The answer is "in a certain sense, yes" and this is demonstrated by…
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26 July 2021
Japanese beetles and other alien species
There is a beetle that has been invading the Italian countryside and cities for some time now, a small insect…
16 June 2021
A turtle’s life
World Sea Turtle Day is held on 16 June. First established in 2008, the day is now supported by Sea…
10 June 2021
The world below
Journey to the Centre of the Earth is a famous science fiction novel written by the great Jules Verne in…
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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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15 September 2021
Can you be intelligent without a brain?
Can you be intelligent without a brain? The answer is "in a certain sense, yes" and this is demonstrated by…
26 July 2021
Japanese beetles and other alien species
There is a beetle that has been invading the Italian countryside and cities for some time now, a small insect…
-
16 June 2021
A turtle’s life
World Sea Turtle Day is held on 16 June. First established in 2008, the day is now supported by Sea…
10 June 2021
The world below
Journey to the Centre of the Earth is a famous science fiction novel written by the great Jules Verne in…
-
15 September 2021
Can you be intelligent without a brain?
Can you be intelligent without a brain? The answer is "in a certain sense, yes" and this is demonstrated by…
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...