RIBOSOME
Ribosome is a complex organelle where protein synthesis is carried out. Ribosome is a complex of protein molecules and ribosomal RNA (rRNA) forming an almost spherical particle 30 nm in diameter. Two parts can be distinguished in a ribosome, a large subunit and a small subunit. There are three kinds of ribosomes: cytosolic ribosomes, mitochondrial ribosomes and chloroplast ones. Ribosomes of eukaryotes, which are in the cytosol, have sedimentation coefficient 80S and consist of small subunits (40S) and large subunits (60S). Small subunits contain one RNA molecule (so called 18S-RNA, 1900 nucleotides long) and 30 to 35 proteins. Large subunits contain three RNA chains (5S-RNA 120 nucleotides long, 5,8S-RNA 160 nucleotides long, and 28S-RNA 4800 nucleotides long) and 45 to 50 proteins. The ribosomes of mitochondria and chloroplasts contain less proteins and various rRNAs.
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Supplementary information
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