What is the primary difference between the smooth and rough endoplasmic reticulum in eukaryotic cells?

• A. The rough ER is responsible for detoxification processes, while the smooth ER is responsible for protein folding.
• B. The smooth ER is involved in photosynthesis, while the rough ER is involved in cellular respiration.
• C. The smooth ER contains ribosomes, while the rough ER does not.
• D. The smooth ER is involved in lipid synthesis, while the rough ER is involved in protein synthesis due to the presence of ribosomes.

Answer: (D)

Verified step by step guidance

1. Understand the structure and function of the endoplasmic reticulum (ER) in eukaryotic cells. The ER is a network of membranes within the cell that plays a crucial role in the synthesis of proteins and lipids.
2. Differentiate between the two types of ER: smooth ER and rough ER. The rough ER is characterized by the presence of ribosomes on its surface, giving it a 'rough' appearance under a microscope.
3. Recognize the function of the rough ER. Due to the presence of ribosomes, the rough ER is primarily involved in the synthesis and folding of proteins. These proteins are often destined for secretion or for use in the cell membrane.
4. Identify the function of the smooth ER. Unlike the rough ER, the smooth ER lacks ribosomes and is involved in the synthesis of lipids, metabolism of carbohydrates, and detoxification of drugs and poisons.
5. Conclude that the primary difference between the smooth and rough ER is their function: the smooth ER is involved in lipid synthesis, while the rough ER is involved in protein synthesis due to the presence of ribosomes.