The Rough ER synthesizes the proteins that are produced by a cell. The rybosomes do the actual synthesis and the Rough ER provides a site for it.
The Kitchen
The oven heats up the raw ingredients of the products of the kitchen and changes them into those products. It is aided by heating elements that do the heating.
The Rough ER is like the oven in a kitchen. They both produce many of the products of their system and are helped by an imbedded part.
