The endoplasmic reticulum (ER) is a system of membranes that extends throughout the cytoplasm from the nuclear envelope to the cell membrane. ER is crucial when it comes to the transport of materials from one part of the cell to another.

Smooth ER is ER without ribosomes attached to it, smooth ER is known as the ‘workbench’ and is involved the metabolic processes such as carbohydrate metabolism.