Abstract
The present review considered: (a) the factors that conditioned the early transition from non-life to life; (b) genome structure and complexity in prokaryotes, eukaryotes, and organelles; (c) comparative human chromosome genomics; and (d) the Brazilian contribution to some of these studies. Understanding the dialectical conflict between freedom and organization is fundamental to give meaning to the patterns and processes of organic evolution.
Highlights
It seems that everything started with a marvelous explosion
With it the earth, was formed at about 4.5 billion years ago, and we have evidence of life in fossils dated around 3.5 years ago, it is clear that life started early in the history of our planet
The sequence of events could be envisaged as follows: (a) nucleoside bases and sugars, either developed on earth or received from the outside space were formed; (b) nucleotides were synthesized and stored in pools; (c) a mineral catalyst at the bottom of the pool afterwards participated in the formation of long single-stranded polynucleotides, some of which were converted to complementary double strands by template-directed synthesis; (d) at least one of these double-stranded ribonucleic acid (RNA) on melting would yield a single-stranded rybozime capable of copying itself and its complement; (e) repeated copying would lead to an exponentially growing population; and (f) the RNA pre-organism would be enclosed by a membrane (Orgel 2004)
Summary
It seems that everything started with a marvelous explosion. there are divergent views, the universe should have emerged from a single, unbelievably small, dense, hot region, 10 billion or more years ago (Halliwell 1991, Adams and Laughlin 2001). Extensive comparisons of genome sequences from widely different modern organisms identified only 60 genes (mostly involved in the translation process) that appear to be universal.
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