g. Formation of the First Cell

Once a self-replicating RNA or DNA system had developed inside a protocell, the resulting structure began to resemble a simple bacterium or virus, and — crucially — it could now regulate its own metabolic activities rather than merely undergoing passive chemical change. This marks the appearance of the first true cell. That first cell is understood to have been anaerobic (able to live without free oxygen, which was still absent from the atmosphere) and heterotrophic, obtaining the energy i …