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If Bacteria are single celled and the most simplest forms of life....then...where do they come from ?
There is no truly "standard model" of the origin of life. But most currently accepted models build in one way or another upon a number of discoveries about the origin of molecular and cellular components for life, which are listed in a rough order of postulated emergence:1. Plausible pre-biotic conditions result in the creation of certain basic small molecules (monomers) of life, such as amino acids. This was demonstrated in the Miller-Urey experiment by Stanley L. Miller and Harold C. Urey in 1953.2. Phospholipids (of an appropriate length) can spontaneously form lipid bilayers, a basic component of the cell membrane.3. The polymerization of nucleotides into random RNA molecules might have resulted in self-replicating ribozymes (RNA world hypothesis).4. Selection pressures for catalytic efficiency and diversity result in ribozymes which catalyse peptidyl transfer (hence formation of small proteins), since oligopeptides complex with RNA to form better catalysts. Thus the first ribosome is born, and protein synthesis becomes more prevalent.5. Proteins outcompete ribozymes in catalytic ability, and therefore become the dominant biopolymer. Nucleic acids are restricted to predominantly genomic use.
...4533 Ma The planet Earth and the planet Theia collide, sending countless moonlets into orbit around the young Earth. These moonlets eventually coalesce to form the Moon. The gravitational pull of the new Moon stabilises the Earth's fluctuating axis of rotation and sets up the conditions for the formation of life.