Introduction

The RNA world and the research on the forming RNA monomers was described in Chapter 11. Progress in the polymerization of monomers to RNA or RNA-like structures will be considered in this chapter. One of the arguments central to the discussion will be that catalysis was essential for the conversion of the complex mixtures of small organic molecules present on the primitive Earth to the biopolymers that led to the origin of life. This catalysis will be illustrated by examples from studies of the synthesis of RNA (Figure 12.1) from its monomeric units.

Catalysis was essential

Life as we know it on the Earth today is built on a complicated array of protein- and RNA-catalyzed reactions. These chemical processes, which occur on the surfaces of organic catalysts, result in, among other things, the formation of a complex array of biopolymers. None of the reactions proceed rapidly enough in the absence of these catalysts to sustain life. It is likely that catalysis was also essential for the prebiotic synthesis of biopolymers on the primitive Earth (Ferris 1993).

No prebiotic simulation experiments have been reported in which biopolymers are formed directly from simple inorganic and organic starting materials. It appears likely that the biopolymers that initiated life were formed by the reactions of more complicated monomers formed in previous prebiotic reactions. Scenarios proposed previously for biopolymer formation have involved the accumulation of solutions of monomers of the same type in one location, evaporation of the water in which they were dissolved, and then the heating of the monomers to the appropriate temperature to form polymers (but not so hot that the polymer decomposes) (Fox 1988).