MOLECULAR EVOLUTION IN THE PRIMITIVE EARTH: FRACTAL DIMENSION OF ARCHAEA tRNAs COMPARED TO COMPUTER-GENERATED RANDOM SEQUENCES

摘要

To examine the general properties of ancient genetic codes, we have evaluated the Manhattan and Euclidean fractal dimensions (Dm, De) of tRNAs in Archaea comparing to the values from mRNA in eukaria and of computer-generated random sequences. Here, fractal dimension was used as a tool to measure complexity, where the most complex sequence results to be the random sequences (with D 1). Dm and De values of ancient informational polymers resulted statistically higher than the ones from bacteria, mitochondria and metazoa and lower than the ones of randomly generated sequences, suggesting that in the primitive Earth informational polymers originated from slightly edited random strings and that during biologic evolution the distance from randomness increased.