The Self Referential Model

Our study of the formation of the genetic code (Guimaraes et al., 2007, and earlier references therein) allowed the proposition of a procedure for obtaining synthesis of proteins that is considered plausible and consistent with the present day knowledge on cellular processes, and can dispose of the requirement for an early mRNA to be translated. It is called self-referential to the tRNAs and based on a simple type of symmetry produced by the dimerization of tRNAs through the complementary anti-codons (Grosjean et al., 1986; Grosjean and Houssier 1990). We will start with a presentation of the model and then give an account of its consistency with the main attributes that have been found adequate and necessary to fit the evolutionary paradigm, e. g. of going from simple to complex arrangements and of providing a driving force or a phenotype with fitness value that can be selected for.

The process is based on a small machine-like system (Fig. 1). Its simplicity offers a fast and high probability mode of evolution, to fill the matrix in a few steps. Such expediency is necessary in the light of the estimated short time span -►

Fig. 1 (continued) The poly-tRNAs may acquire different configurations: some become the ribosomal RNAs and others form aligned anticodons, whose copies are codon strings (mRNA). The meaningful (to the system being formed) association is selective and specific (cognitive): proteins should be intrinsically stable and efficient binders, and should bind the same carriers that were involved in their production. (3) Ribosomal translation. Protein synthesis is directed by strings and the carriers become the decoding system. Different types of cytosolic dimers of tRNAs (both uncharged, one of them charged, both charged), and their relative concentrations, may have regulatory functions

5 Self-Referential Formation of the Genetic System (1)

Carriers Capture Fishing of Synthesis Elongation of strings and of letters carriers of strings letters (synthetase) (transferase)

Protein liberated

Unstable loops

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