Four processes were needed for the spontaneous origin of life on Earth: 1.  Non-­‐living synthesis of simple organic molecules 2.  Assembly of these molecules into polymers 3.  Origin of self replica=ng molecules that made inheritance possible 4.  Packaging of these molecules into membranes with an internal chemistry different from their surroundings Protocells: Combina=ons of abio=cally produced molecules surrounded by a membrane or membrane–like structure. Exhibit some of the proper:es associated with life •  simple reproduc=on •  simple metabolism •  the maintenance of an internal chemical environment different from that of their surroundings. Protocells could have developed from coacervate droplets: •  Complex spherical units that spontaneously form when concentrated mixtures of macromolecules are held in the right temperature, ionic composi:on, and pH •  Absorb and incorporate various substances from the surrounding solu:on How could a protocell develop? 1.  FaHy acids spontaneously form membranes (anima=on #4, video clip #3 from Wormhole) 2.  RNA enters the membrane (anima=on #5) •  Creates proteins •  Replicates itself 3.  Structure divides into two when surface area is too large (anima=on)