My Smore Flyer
In Journey into the Cell, we looked at the structure of the two major types of cell, prokaryotic and eukaryotic cells. The endoplasmic reticulum is a network of tubules and flattened sacs that serve a variety of functions in the cell. There are two regions of the ER that differ in both structure and function. One region is called rough ER because it has ribosomes attached to the cytoplasmic side of the membrane. The other region is called smooth ER because it lacks attached ribosomes. Typically, the smooth ER is a tubule network and the rough ER is a series of flattened sacs. The space inside of the ER is called the lumen. Since the ER is connected with the nuclear envelope, the lumen of the ER and the space inside the nuclear envelope are part of the same compartment. The rough endoplasmic reticulum manufactures membranes and secretory proteins. In leukocytes the rough ER produces antibodies. In pancreatic cells the rough ER produces insulin. The rough and smooth ER are usually interconnected and the proteins and membranes made by the rough ER move into the smooth ER to be transferred to other locations. The smooth ER has a wide range of functions including carbohydrates and lipid synthesis. It serves as a transitional area for vesicles that transport ER products to various destinations. In liver cells the smooth ER produces enzymes that help to detoxify certain compounds. In muscles the smooth ER assists in the contraction of muscle cells, and in brain cells it synthesizes male and female hormones.