Why does your car still run with dead battery cells once it as a jump started?

Why does your car still run with dead battery cells once it as a jump started?
Because as the engine turns it produces electricity through the alternator but not stored so once the engine is switched off the car has to rely on the battery to start again. For instance, an F1 race car carries no battery so it has to be started externally, jump started really. Once it stalls it cannot get itself going again unless there is someone there to push start it (not a good idea - they are heavy and have a habit of leaving you flat on your face...)