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Ribosomal ribonucleic acid

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The ribonucleic acid component of the ribosome


Ribonucleic acid (RNA) is a nucleic acid marked by being generally single-stranded, and composed of repeating nucleotide units of ribose sugar, phosphate group, and nitrogenous base. One of the main functions of RNA is for protein synthesis. There are three major types of RNA involved in this process: (1) messenger RNA (mRNA), (2) transfer RNA (tRNA), and (3) ribosomal RNA (rRNA).

Ribosomal ribonucleic acid (rRNA) is a ribonucleic acid that, together with proteins, makes up the ribosome. A ribosome is a cytoplasmic particle that serves as the site of protein synthesis. It has three binding sites: A, P, and E sites. The A site binds to tRNA with an amino acid (called aminoacyl-tRNA). The P site is the site in a ribosome occupied by tRNA carrying the growing peptide chain (i.e. peptidyl tRNA). The E site is the site for decylated tRNA on transit out from the ribosome.1 Using messenger RNA as a template, the ribosome traverses each codon and pair it with a specific amino acid linked to a transfer RNA.

Ribosomal RNA, in turn, does not carry the code in making proteins. Rather, it forms the two subunits (i.e. large subunit and small subunit) that make up a ribosome. The large subunit serves as a ribozyme that acts as an enzyme that catalyzes peptide bond formation between two amino acids.

Ribosomal RNAs are used as basis in taxonomy and evolution. Ribosomal DNAs, which are the genes coding for ribosomal RNAs, are sequenced in order to identify the taxonomic group of an organism as well as estimate the rate of species divergence.

Abbreviation / Acronym:

  • rRNA
  • ribosomal RNA

See also:

1 A-site, P-site and E-site. Retrieved from [1]