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Biological Environment > Ribosome |
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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A tiny machine which is part of the mechanism of life.
Ribosomes occur both as free particles within cells and as particles attached to the membranes of the endoplasmic reticulum. A ribosome is made of about 40% protein and 60 % nucleic acid. It is composed of four nucleic acid molecules and about 70 different proteins. A ribosome consists of two parts, a larger one and a smaller one, each of which has a characteristic shape. Ribosomes are very numerous in a cell and account for a large proportion of its total nucleic acid. Every second in every animal cell, around 1 million amino acids are added to growing proteins. The ribosome is the molecular machine which makes this happen. It reads the information in messenger RNA (mRNA) to tell it which amino acids to add to the protein it is growing. One ribosome can add between 3 and 5 amino acids to the protein it is growing every second. The ribosome has two parts, the large and small subunits. Each of these subunits is made of ribosomal RNA (rRNA) and about 25 proteins. The RNA and proteins which make ribosomes is different in bacteria than in eukaryotes. Also it varies between species of eukaryotes. However the structure and function is always the same. We conclude that this machinery appeared only once, and has been modified round this common theme during evolution. As protein is made it passes through a hole in the large sub-unit. The exact way the ribosome works is not understood. Visit Soccearth to get an idea of the size of a ribosome. |
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Biological Environment > Ribosome |
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Basic Information |
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