Chemotons

The author considers his chemoton model not as an intermediate station of biogenesis, but as a basic model for living systems. Greatly simplified, the three cycles are ... 

According to Popa (2004) the chemoton model is a virtual chemical network and does not promote any specific chemistry . Without doubt, Gdnti s model represents an important, well-thought-through model for a primitive living system. 

Autopoiesis and the chemoton a comparison of the views of Ganti with those of Maturana and Varela... 

One advantage of the idea of autopoiesis is its extreme simplicity. This comes at the cost of a lack of structural and mechanistic details. Ganti s chemoton provides a more detailed and more complex view of the unit of cellular life (Ganti, 1975 2003). Let s now sketch the basic theory of the chemoton in order to draw a comparison with autopoiesis. 

The chemoton scheme is illustrated in Figure 8.10. It consists of three subsystems a metabohc autocatalytic network, a bilayer membrane, and arephca-ble information carrier molecule, or template. Here, as in autopoiesis, the membrane is an important player. However, what happens within the membrane is depicted in more detail. In particular, looking at Figure 8.10, note that the entire system is fed by nutrient X which hrst feeds the metabolic network with the various A molecules. This is an autocatalytic chemical cycle, autocatalytic because two Ai molecules are produced from the original single Ai molecule. 

Figure 8.10 Ganti s chemoton (redrawn from Maynard-Smith and Szathmary, 1995, based on the original by Ganti, 1984). The metabolic subsystem, with intermediates Ai -> A2 ->. . . A5, is an autocatalytic chemical cycle, consuming X as nutrient and producing Y as waste material pV is a polymer of n molecules of V which undergoes template replication R is a condensation byproduct of this replication, needed to turn into T, the membranogenic molecule the symbol Tm represents a bilayer membrane composed of m units made of T molecules.

Maynard-Smith and Szathmary (1995) discuss at length some of the implications of the chemoton, for example, the question of how the chemoton has heredity. They point out some of the difficulties in implementing the chemoton but conclude by saying (Maynard Smith and Szathmary, 1995) ... 

Ganti, T. (1975X Organization of chemical reactions into dividing and metabolizing units the chemotons. BioSystems, 7, 15-21. 

Chemoton elmelet 1. hotel A fluid automatdk elmeleti alapjai (Translated as Chemoton Theory. Vol. 1. Theory of Eluid Automata). OMIKK. 

Abstract Minimal protocell concepts have high intellectual and practical value. Following chemoton theory, developed by Tibor G4nti in 1971, we suggest that a minimal protocell... 

Keywords Autocatalysis Chemoton Evolution Heredity Infrabiological systems Lipid world Metabolism Minimal life Protocell Unit of evolution... 

Although we take the chemoton as the working definition of minimal life, it is important that its three subsystems can be combined to yield three different... 

Fig-1 Ganti s abstract chemoton model for minimal life. A, are intermediates of the metabolic cycle, pV is a template molecule consisting of n pieces of monomer V, V is the activated monomer, T is the precursor to the membranogenic molecule T. Tm denotes a membrane consisting of m pieces of T. The system works at the expense of the difference between X and Y. Note that all three subsystems are autocatalytic... 

Fig. 2 Elementary combinatorics of infrabiological systems. The chemoton is a biological minimal system comprising three qualitatively different subsystems (metabolism, membrane, and template)...

Verhds J (1989) Appendix. In Ganti T (ed) Chemoton elmelet II (Chemoton theory Vol 2). OMIKK, Budapest, Hungary, pp 201-216... 

Ganti T (2004) Chemoton theory, Vol I Vol II. Kluwer, Dordrecht, The Netherlands... 

The first model of a system that is capable of growing by metabolism and of dividing by fission was proposed - with the name of chemoton - by Ganti (1975). Such a system receives metabolites from the environment, expels waste products, and performs a metabolic cycle that begins with one molecule and ends by making two of them. The system is therefore autocatalytic, but it is not using enzymes, and this leaves us in the dark about its biological potential. 

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