Читать книгу Snyder and Champness Molecular Genetics of Bacteria - Tina M. Henkin - Страница 172

The translation of the sequence of nucleotides in mRNA into the sequence of amino acids in a protein occurs on the ribosome. The overall process of translation is highly conserved in bacteria, archaea, and eukaryotes, and the machinery is also highly conserved. As mentioned in “rRNAs and tRNAs” above, the ribosome is one of the largest and most complicated structures in cells, consisting of three different RNAs and over 50 different proteins in bacteria. It is also one of the major constituents of the bacterial cell, and much of the biosynthetic capacity of the cell goes into making ribosomes. Each cell contains thousands of ribosomes, with the actual number depending on the growth conditions. It is also one of the most evolutionarily highly conserved structures in cells, having remained largely unchanged in shape and structure from bacteria to humans. The key role of protein synthesis in the cell has led to the development of important antibiotics that target the translational machinery (Box 2.3).

The ribosome is an enormous enzyme that performs the complicated role of polymerizing amino acids into polypeptide chains, using the information in mRNA as a guide. As such, a better name for it might have been protein polymerase, by analogy to DNA and RNA polymerases. The historical name “ribosome” was coined before its function was known, because it is large enough to have been visualized under the electron microscope and so it was called a “some” (for body) and “ribosome” because it contains ribonucleotides. The recent determination of the structure of the ribosome (see below) has led to important insights into how it performs its function of polymerizing amino acids.