ribosomes defined in 1951 yearribosomes - ribosomes;
ribosomes - Granules of protein and RNA present in the cytoplasm of all types of organism, about 100 Angstrom in diameter and hence invisible with a light microscope. In eucaryotic cells they are often attached to endoplasmic reticulum. Their RNA is synthesized in nucleoli. They are the site of protein synthesis; messenger RNA attaches to them, and there receives molecules of transfer RNA bearing amino acids. Ribosomes are often linked together in a chain probably by a long molecule of messenger RNA; such groups are called polyribosomes, polysomes or ergosomes. Number of ribosomes in a polysome is probably related to length of messenger RNA molecule, and this in turn to the length of polypeptide chain to be formed.
near ribosomes in Knolik
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