RNA, the 'Other' Genetic Material

For decades, ribonucleic acid, or RNA, has been known as the "other" genetic material, the lesser known cousin of deoxyribonucleoic acid, or DNA.

While RNA is important for DNA duplication and for the translation of DNA into proteins, it is DNA and its reputation as the genetic "blueprint" for most of life that gets all the glory.

Finally though, RNA may be getting its proper due.

RNA is biochemically distinguished from DNA by the presence of an additional chemical group, called a hydroxyl, to the sugar scaffolding that holds together the "letters" that make up the genetic code known as bases. The presence of the hydroxyl group makes RNA more reactive, but also less stable, than DNA.

RNA also has the crucial distinction of having a U-uracil--instead of a T--thymine--as one of its bases. (The other three bases are A, G andC, which stand for adenine, guanine and cytosine, respectively.)

The best known examples of RNA are messenger RNA (mRNA), ribosomal RNA (rRNA) and transfer RNA (tRNA) [artist rendering above].

MRNA serves as a transient middleman between the instructions found in DNA and the complicated molecules known as proteins that are the functional components of the cell, while rRNA and tRNA are involved in the actual synthesis of proteins.

With the exception of a few viruses that use RNA instead of DNA as its primary genetic material, RNA has largely been regarded as an important supporting character, but definitely not the star, when it comes to the ensemble of molecules important for life.

Over the past decades, however, scientists have discovered various "small" RNA that serve a broad range of cellular functions separate from DNA, including the regulation of cellular development, pathogen defense and stress response. This suggests RNA is more significant for keeping a cell alive and running smoothly than previously thought and scientists expect new functions for RNA will be discovered.

--Ker Than

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