In reality, Pollack says, the membrane isn't key to cell integrity because the water inside the cell isn't normal water - it's organized by proteins to form a gel. It may even shed light on how cells came into existence when life on Earth began. Cell biology is built on the premise of aqueous solution behavior, or how things work in normal water with water being a neutral carrier. If that's wrong, then many of the constructs will have to be re-evaluated. Traditionally, biologists have accepted the idea that cells are surrounded by a relatively impermeable lipid membrane.
Problems quickly arise with such a scenario, however.
And pumps require energy. Sodium concentrations are lower inside cells than outside, for instance, and scientists have proposed a sodium pump to help maintain that equilibrium. But the sodium pump alone has been estimated to consume as much as 35 percent of a cell's energy. As a result, sodium is kept outside, with or without a membrane. Unlike the pump theory, no energy is required to keep the equilibrium - it all follows from the cytoplasm's basic chemical features.