Final answer:
The smooth ER and Rough ER perform different functions due to the presence of ribosomes on the Rough ER that are involved in protein synthesis, while the Smooth ER is involved in lipid synthesis, calcium storage, and detoxification.
Step-by-step explanation:
The smooth ER and the Rough ER have distinct functions mainly because of the presence or absence of ribosomes on their surfaces. The Rough ER (RER) has a bumpy appearance due to the presence of ribosomes, which are responsible for the synthesis of proteins that are normally destined for the cell membrane or for export from the cell. The proteins synthesized here may undergo glycosylation before being shuttled to the Golgi apparatus for further modification and sorting. In contrast, the Smooth ER (SER) lacks ribosomes and thus has a smooth appearance. Its functions include lipid synthesis, calcium ion storage, drug detoxification, and metabolism of carbohydrates.