Before describing the rough endoplasmic reticulum function and structure, it is important to have an idea about what exactly endoplasmic reticulum is. ER, short for endoplasmic reticulum, is an organelle responsible for producing and transporting lipids and proteins to various locations in the body. The term endoplasmic reticulum has been derived from the words ‘reticulum’ and ‘endo’ which mean network and inside of the cytoplasm respectively. The structure of the ER is composed of many folds, although its membrane is in the form of a thin sheet that opens into a single arc. It is a part of the eukaryotic cells which is capable of manufacturing proteins for itself and for various other cell components like the Golgi apparatus, lysosomes, cell membrane as well as the secretary vesicles.