Spontaneous self-reproduction

It is important to point out the main message of these experiments. This is that, by a very simple set-up, a spontaneous self-reproduction of spherical compartments can be obtained. Since such spherical compartments can be considered as models and/or precursors of biological cells, the hypothesis was put forward, (Bachmann et al, 1992), that this autocatalytic self-reproduction process might have been of relevance for the origin of life. 

In all cases, the rate versus [surfactant] profiles are characterized by a sharp change of the rate at [surfactant] > cac. This is the typical behavior of systems that operate on a cooperative basis [32]. Here the cooperativity occurs at the level of the association of the monomeric surfactant to form the aggregate with the onset of its new properties. The outburst of reactivity associated with the spontaneous formation of aggregates once the cac is reached has stimulated Luisi and coworkers [33,34] to introduce the provocative idea of autopoiesis . According to their definition, an autopoietic system is an organizational unit capable of selfmaintenance and, hence, self-reproduction. To illustrate this point they have [33],... 

The main point of this chapter is to show that supramolecular aggregates can play an important role in the early history of the origin of life. The main driving force in all processes we have illustrated is the hydrophobic interaction—this is responsible for the self-assembly of vesicles, for the binding of hydrophobic substances to the vesicle membranes and the corresponding autocatalytic self-reproduction of micelles and vesicles, as well as for the corresponding chemical events of polymerization. Since the hydrophobic forces take place generally spontaneously and with... 

Figure 9. The hypothetical "hydrophobic start" in the origin of life. The hydrophobic, spontaneously formed vesicles can undergo self-reproduction if they bind the corresponding precursor they can scavenge hydrophobic peptides and condense them into longer chain once a hydrophobic condensing agent is also present and they can also bind water-soluble peptide catalyst (or any other potential hydrophobic catalyst) and induce an enzyme-like turnover. The catalyst can eventually be internalized, thus giving rise to a protocellular structure capable of a primitive metabolism.

The self-reproduction mechanism illustrated here for vesicles is of course extremely primitive with respect to the self-replication mechanisms of RNA. However, one should recognize that the first prebiotic self-replicators cannot have been chemically well-developed and sophisticated macromolecules. Most likely, the first replicators were primitive structures. In this sense, the self-reproducing supra-molecular structures have a distinct relevance, since the reproduction mechanism happens almost spontaneously. 

Self-assembled template-directed systems containing reactive groups provide pathways towards systems displaying copying, information transfer and replication. This may lead to spontaneous condensations within the self-assembled entity into the final covalent structure. A special case is the reproduction of the template itself by replication or self-... 

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