first it has evolved to be autonomous, to survive as an independent living unit. This autonomy depends, in turn, on organization—on the cell’s interior anatomy. A cell is not a blob of chemicals; it has distinct structures, or subunits, within it that allow it to function independently. The subunits are designed to supply energy, discard waste, store nutrients, sequester toxic products, and maintain the internal milieu of a cell. Second, a cell is designed to reproduce, so that one cell can produce all the other cells that populate the organism’s body. And finally, for multicellular organisms,
...more
