What is the difference between rough ER and smooth ER?

The rough endoplasmic reticulum (rough ER) and smooth endoplasmic reticulum (smooth ER) are two distinct types of endoplasmic reticulum found in eukaryotic cells, each with unique structures and functions.

Rough Endoplasmic Reticulum (Rough ER)

• Structure: The rough ER is studded with ribosomes on its cytoplasmic surface, giving it a "rough" appearance under a microscope.
• Function: It is primarily involved in the synthesis of proteins. The ribosomes on the rough ER translate mRNA into polypeptide chains, which are then folded and modified within the ER lumen.
• Location: It is typically located near the nucleus and the Golgi apparatus, facilitating the transport of synthesized proteins.

Smooth Endoplasmic Reticulum (Smooth ER)

• Structure: The smooth ER lacks ribosomes on its surface, giving it a "smooth" appearance.
• Function: It is involved in the synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions. The smooth ER plays a crucial role in lipid metabolism and hormone production.
• Location: It is distributed throughout the cytoplasm and is often more tubular in structure compared to the rough ER.

Final Answer

The main difference between rough ER and smooth ER lies in their structure and function: rough ER has ribosomes and is involved in protein synthesis, while smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification processes.