RIBOSOMAL RNA
Ribosomal RNA (rRNA) is a structural component of a ribosome. rRNA consists of a large and a small subunits. The portion of rRNA in an eukaryotic ribosome makes approximately 60%. Eukaryotes have 5S-rRNA, 5,8S- rRNA è 28S- rRNA in a large subunit and 18S- rRNA in a small one. The names of rRNA types came from the rate of their sedimentation rates. Sedimentation rate is measured in Svedberg’s units (S). It depends both on the masses of particles and on their forms. Prokaryotes have 5S- rRNA and 23S- rRNA in a large subunit and 16S- rRNA in a small one; plants - 25S- rRNA in a large subunit and 16S- rRNA in a small one. In a ribosome rRNA forms a complex with ribosome proteins.