(2) they contain receptors and channels that allow specific molecules, such as ions, nutrients, wastes, and metabolic products, that mediate cellular and extracellular activities to pass between organelles
2 functions of the cell membrane are to be a barrier type by keeping the constituents of the cell in and unwanted substances out and the other function is to be a gate type allowing transport into the cell of essential nutrients and movement from the cell of bad or waste products.
