What is the name given to the ER when it has ribosomes attached to its outer surface?

Step-by-step solution

The ER often shows ribosomes attached to their outer surface. The endoplasmic reticulum bearing ribosomes on their surface is called rough endoplasmic reticulum (RER). In the absence of ribosomes they appear smooth and are called smooth endoplasmic reticulum (SER).RER is frequently observed in the cells actively involved in protein synthesis and secretion. They are extensive and continuous with the outer membrane of the nucleus.The smooth endoplasmic reticulum is the major site for synthesis of lipid. In animal cel