What are the structural and functional differences between the rough endoplasmic reticulum (ER) and the smooth endoplasmic reticulum (ER)?

• A. The rough ER is responsible for detoxification processes, while the smooth ER is responsible for protein synthesis and has ribosomes on its surface.
• B. The rough ER has ribosomes on its surface and is involved in protein synthesis, while the smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification.
• C. The rough ER and smooth ER both have ribosomes on their surfaces and are involved in protein synthesis.
• D. The rough ER is involved in lipid synthesis, while the smooth ER is involved in protein synthesis and has ribosomes on its surface.

Answer: (B)

Verified step by step guidance

1. Identify the main structural difference: The rough endoplasmic reticulum (ER) has ribosomes attached to its cytoplasmic surface, giving it a 'rough' appearance under a microscope, whereas the smooth ER lacks these ribosomes and appears 'smooth'.
2. Understand the functional role of the rough ER: The presence of ribosomes on the rough ER is crucial for its role in protein synthesis. These ribosomes translate mRNA into polypeptide chains, which are then folded and modified within the rough ER.
3. Explore the functional role of the smooth ER: The smooth ER is primarily involved in lipid synthesis, including phospholipids and steroids. It also plays a significant role in detoxifying certain chemicals and metabolizing carbohydrates.
4. Clarify the misconception: The rough ER is not involved in detoxification processes; this is a function of the smooth ER. Similarly, the smooth ER is not involved in protein synthesis, as it lacks ribosomes.
5. Summarize the key differences: The rough ER is characterized by ribosomes and is involved in protein synthesis, while the smooth ER lacks ribosomes and is involved in lipid synthesis and detoxification processes.