What is the primary difference between rough endoplasmic reticulum (ER) and smooth endoplasmic reticulum (ER)?

• A. Rough ER is found only in animal cells, while smooth ER is found only in plant cells.
• B. Rough ER is involved in lipid synthesis, while smooth ER is involved in protein synthesis.
• C. Rough ER is responsible for detoxification, while smooth ER is responsible for energy production.
• D. Rough ER has ribosomes on its surface, while smooth ER does not.

Answer: (D)

Verified step by step guidance

1. Begin by understanding the structure and function of the endoplasmic reticulum (ER), which is an essential organelle in eukaryotic cells involved in the synthesis and processing of proteins and lipids.
2. Identify the two types of ER: rough endoplasmic reticulum (RER) and smooth endoplasmic reticulum (SER). The primary structural difference is that RER has ribosomes attached to its cytoplasmic surface, giving it a 'rough' appearance under a microscope.
3. Recognize the function 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 ER.
4. Understand the function of the smooth ER. Unlike the rough ER, the smooth ER lacks ribosomes and is primarily involved in lipid synthesis, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions.
5. Conclude that the primary difference between rough ER and smooth ER is the presence of ribosomes on the rough ER, which are absent on the smooth ER, leading to their distinct roles in the cell.