Animation of a typical human cell, showing the endoplasmic reticulum and associated structures. The endoplasmic reticulum (ER) is a group of structures associated with the nucleus (purple). It has two main components, known as rough ER and smooth ER. Rough ER is so called as its outer surface is studded with ribosomes (grey, flashing blue), which make proteins (blue balls) from genetic instructions. These are folded into shape inside the rough ER. The smooth ER lacks ribosomes, and instead mainly makes lipids (yellow balls). When they are complete, the lipids and proteins bud out of the ER membrane in vesicles, spheres derived from the ER membrane itself. The proteins move to the Golgi apparatus, entering through its cis Entry face. In the Golgi apparatus the protein is packaged and biochemically labelled so that it is taken to the correct location in the body. The newly-packaged protein buds out of the trans Exit face, fuses with the cell membrane, and is secreted entirely from the cell. This animation is available with the components labelled. See K005/1172.