ABSTRACT
Over the last two decades, the concepts concerning the role of RNA molecules in the cell changed dramatically. It is now evident that RNAs are not only passive players providing templates and decoding machinery for translation of the genetic information contained in the DNA into proteins, but also perform a number of functions crucial for many other cellular processes. In the beginning of 1980s, the catalytic properties of self-splicing introns and RNase P RNAs were discovered [1]. These findings prompted formulation of the hypothesis of a primordial ‘‘RNA world’’ which preceded today’s ‘‘DNA-protein world’’ [2]. According to this concept, in the prebiotic RNA world, RNA molecules were responsible not only for transmission of genetic information but also carried out all structural and enzymatic functions. Subsequently, a more stable DNA replaced RNA as the primary carrier of genetic information, and the majority of structural and catalytic functions were taken over by proteins.
