Cells contain different types of RNA with many important functions in living organisms. The following are the most important types of RNAs:

mRNA(messenger RNA)is the product of protein-coding genes. It is produced in the nucleus and transported to the cytoplasm (in eukaryotes).

tRNA(transfer RNA) is a group of RNA molecules participating in the protein synthesis process by transportingamino acids. Several kinds of tRNA exist, each characterized by a specific anticodon in one end. The anticodon base will pair with a complementary codon in the mRNA, after which the corresponding amino acid carried by the tRNA is incorporated into the growing protein.

rRNA(ribosomal RNA) is the main component of the ribosomes and forms two subunits: a large subunit containing the 5S, 5.8S and 28S molecules, and a small subunit containing the 18S molecule. The 28S and 18S molecules are easily recognized as distinct bands on a gel picture after electrophoresis with total RNA.

regulatory RNAs: Apart from protein synthesis, RNAs also regulategene expressionand act as a cellular immune system. Examples for these aremicroRNAsand small interfering RNAs, respectively.