Endoplasmic Reticulum
Smooth ER
The smooth endoplasmic reticulum has functions in several metabolic processes, including synthesis of lipids, metabolism of carbohydrates and calcium concentration, drug detoxification, and attachment of receptors on cell membrane proteins. It is connected to the nuclear envelope. Smooth endoplasmic reticulum is found in a variety of cell types (both animal and plant) and it serves different functions in each. The Smooth ER also contains the enzyme Glucose-6-phosphatase which converts Glucose-6-phosphate to Glucose, a step in gluconeogenesis. The Smooth ER consists of tubules and vesicles that branch forming a network. In some cells there are dilated areas like the sacs of rough endoplasmic reticulum. The network of smooth endoplasmic reticulum allows increased surface area for the action or storage of key enzymes and the products of these enzymes. The smooth endoplasmic reticulum is known for its storage of calcium ions in muscle cells.
Rough ER
Endoplasmic reticulum manufactures substances in the cell. It is a set of flattened membrane sheets. Rough ER has ribosomes attached to it. It manufactures proteins. Smooth ER contains enzymes that manufacture fats, phospholipids and steriods. Endoplasmic reticulum transports the substances made around the cell so that it can be exported. Proteins for use in the cell are made by ribosomes free in the cytoplasm. Golgi bodies receive substances from ER for export.