What makes something “alive”? Anyone could deduce that a galloping horse is alive and a car is not, but why? We cannot say, “If it moves, it’s alive,” because a car can move, and gelatin can wiggle in a bowl. They certainly are not alive. What characteristics do define life? All living organisms share five basic characteristics:
Order. All organisms consist of one or more cells
with highly ordered structures: atoms make up molecules, which construct cellular organelles, which are contained within cells. This hierarchical organization continues at higher levels in multicellular organisms
and among organisms.
CMP Bio World 