The cell membrane is a phospholipid bilayer membrane that separates the cell from its environment and regulates the transport of molecules and signals into and out of the cell. The nuclear envelope is the membrane around the nucleus of the cell. The nucleus itself is not part of the Endomembrane system. The endoplasmic reticulum is a synthesis and transport organelle that is an extension of the nuclear envelope. The Golgi apparatus acts as the packaging and delivery system for molecules. Lysosomes are the "digestive" units of the cell. They utilize enzymes to break down macromolecules and also act as a waste disposal system. Vacuoles act as storage units in some cells. (Vacuoles do not communicate with the organelles of the endomembrane system and therefore are sometimes not considered part of it.)Vesicles are small membrane-enclosed transport units that can transfer molecules between different compartments.
