In the Rise of Life, Several Steps Have Been Proposed

In the rise of life, several steps have been proposed, beginning with the formation of building-block monomers from simple molecules.The next step involved polymerization of monomers to form more complex polymers.Polymerization reactions were likely facilitated by conditions that increased the concentrations of monomers.But this step may never have resulted in the emergence of living cells without the formation of a(n) _______ that enclosed reacting molecules within a protocell, separating them from the surrounding environment.The protocell would have protected the molecules and facilitated their interactions in ways that could never have been achieved by clay surfaces or evaporating pools of water.