The nucleus controls the cell like a computer, the plasma membrane surrounds the cell like doors and windows on a car, and the lysosome breaks down waste like a catalytic converter. The ribosome builds proteins like cylinders in an engine, the endoplasmic reticulum transports materials like fuel lines, and the smooth endoplasmic reticulum stores lipids like a gas tank. The Golgi apparatus packages proteins like a fuel pump, mitochondria produce energy like an engine, vacuoles store waste like a muffler, and chloroplasts perform photosynthesis like valves.