Microbial Life > Research Methods > Genomics > Ribosomal RNA
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Ribosomes and Ribosomal RNA: (rRNA)


Created by George Rice, Montana State University


Crystal structure of ribosomal sub-units.
Structure of the 30S subunit from T. thermophilus (left) and structure of the 50S subunit from D. radiodurans. From Ribosomal structure, and ribosome-antibiotic interactions.


Ribosomes are the universal ribonucleoprotein particles that translate the genetic code into proteins. They are built of two subunits that associate upon initiation of protein synthesis. Typical eubacterial ribosomes (70S) consist of 57 different molecules (3 rRNAs and 54 proteins) and can dissociate into a small (30S) and a large subunit (50S). The small subunit is responsible for the formation of the initiation complex, performs the decoding of the genetic information, and controls the fidelity of codon-anticodon interactions. The large subunit catalyzes the peptide bond formation and provides the path for the nascent polypeptide chain.


16S Ribosomal RNA: ("the molecule" of modern genomics)


The section (or gene) that codes for ribosomal RNA in a cell is the 16S rRNA gene (or rDNA gene).
  • Every cell has a 16S rRNA gene as the ribosomal RNA (rRNA) is an integral part of the ribosome, which is responsible for making cellular proteins.
  • This gene is only about 1550 bp in length in prokaryotes and every cell has from one to more than 25 copies of this gene.
  • The 16S rRNA molecule folds itself into a shape that must fit like a puzzle piece with other molecules and consequently, some structural elements must be maintained.
  • Therefore, some sections of the sequence may vary and others may not.


 E. coli small subunit rRNA variability map.
Areas in red and grey may vary in this molecule, and areas in violet and blue may not.



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