Ribozymes are RNA molecules that catalyze chemical reactions. Most biological processes do not happen spontaneously. For example, the cleavage of a molecule into two parts or the linkage of two molecules into one larger molecule requires catalysts, that is, helper molecules that make a reaction go faster. The majority of biological catalysts are proteins called enzymes. For many years scientists assumed that proteins alone had the structural complexity needed to serve as specific catalysts in cells, but around 1980 the research groups of Tom Cech and Sidney Altman independently discovered that some biological catalysts are made of RNA. These two scientists were honored with the Nobel Prize in chemistry in 1989 for their discovery.

Structure and Function

The RNA catalysts called ribozymes are found in the nucleus, mitochondria, and chloroplasts of eukaryotic organisms. Some viruses, including several bacterial viruses, also have ribozymes. The ribozymes discovered to date can be grouped...