Endoplasmic Reticulum
The endoplasmic reticulum (ER) is a large network of tubular flat membranous canals which resemble a maze. It is connected to the nuclear envelope of the nucleus. The convoluted canals provide greater surface area for reactions to occur.
There are two types of ER - rough and smooth ER: Rough ER has ribosomes attached to it, which allows the rough ER to make proteins (both for use within the cell and for export). Smooth ER has no ribosomes attached to it. Its job is to synthesize lipids, which are essential for maintaining the cell membrane and producing hormones. In addition, smooth ER in the liver breaks down glycogen into glucose through hydrolysis. Smooth ER in the liver also plays a role in drug detoxification as peroxisome vesicles are attached to it. The canals of the ER can act as a storage space for synthesized materials and serve as a transportation route for them. The proteins synthesized by the ER are not finished products and must be processed in the golgi apparatus before they can be used. |