The rough endoplamic reticulum (rough ER) is found in the cytoplasm outside of the nuclear envelope. The rough ER is a complex network of tubes and sacs that are enclosed by membranes and is studded in ribosomes. It is the site of protein synthesis and transportation.
Smooth Endoplasmic Reticulum
The smooth endoplasmic reticulum (smooth ER) is found in the cytoplasm outside of the rough ER. It is filled channels that are enclosed by a phospholipid bilayer. It is the place where lipid sythesis occurs. It also modifies proteins and breakes down toxins.