Exploring the Smooth ER:
The smooth ER has no ribosomes on its surface. This type of membrane is often involved in metabolism of carbohydrates, production of lipids, and detoxification. This ER contains enzymes vital to produce lipids such as oils, phospholipids, and steroids. For instance, phospholipids are necessary in plant cells to form a semi-permeable cell membrane, and plants also need steroids for certain hormones (yes, contrary to the popular misconception, plants use hormones too, not just animals).
In addition, the smooth ER helps to detoxify drugs and poisons by adding hydroxyl groups. This in effect helps to get rid of the toxic molecules by making them more soluble.