GENOME EVOLUTION About 11 to 15 billion years ago all of the matter and energy in the universe was concentrated into an area the size of an atom. At this moment, matter, energy, space and time did not exist. Then suddenly, the Universe began to expand at an incredible rate and matter, energy, space and time came into being (big bang).

GENOME EVOLUTION At the beginning of the universe, the whole matter of the universe was in an extremely dense and hot fireball. Then a vast explosion occurred. The matter was broken into pieces, which were thrown out with high speed in all directions forming stars and galaxies.

GENOME EVOLUTION Our solar system formed about 5 billion years ago

GENOME EVOLUTION Essential to the spontaneous origin of life was the availability of organic molecules as building blocks. The famous "prebiotic soup" experiment by Stanley Miller (1953) had shown that amino acids, arose among other small organic molecules spontaneously in the lab by sparking a mixture of methane, hydrogen, ammonia and water.

GENOME EVOLUTION Observations of Jupiter and Saturn had shown that they contained ammonia and methane, and large amounts of hydrogen were inferred to be present there as well. These reducing atmospheres of the giant planets were regarded as captured remnants of the solar nebula and the atmosphere of the early Earth was assumed by analogy to have been similar.

GENOME EVOLUTION The interactions of these molecules would have increased as their concentrations increased. Reactions would have led to the building of larger, more complex molecules. A pre-cellular life would have began with the formation of nucleic acids.

GENOME EVOLUTION Chemicals made by these nucleic acids would have remained in proximity to the nucleic acids. Eventually the pre-cells would have been enclosed in a lipid-protein membrane, which would have resulted in the first cells.

GENOME EVOLUTION It is now widely agreed that at the origin of life there was not the current DNA/(RNA)/protein system for gene information, catalysis, regulation, and structural functions. It would beg the question, what came first, protein or DNA?

GENOME EVOLUTION Protein catalysis without gene information, which allows it to be maintained and propagated, is not sufficient in the long term, and DNA gene information without catalysis, necessary for the function of life, would be useless as well.

GENOME EVOLUTION Instead, it is assumed that RNA acted as a precursor of both protein and DNA, in the sense that it can serve both as catalyst (like protein enzymes) and as carrier of genetic information (like DNA, RNA is a polynucleotide).

GENOME EVOLUTION Even in the modern cell ribozymes (catalytic RNAs) still play a vital role. In the ribosome, the synthesis of the peptide chains of proteins from RNA code is accomplished by ribozymes. They also catalyze splicing of RNA.

GENOME EVOLUTION First DNA genome. Development of protein enzymes replaced the catalytic activities of ribozymes. First DNA genomes comprised many separate molecules. Acquisition of new genes. i. duplication ii. recombination