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

• A. The rough ER has ribosomes attached to its surface, while the smooth ER does not.
• B. The rough ER is found only in animal cells, while the smooth ER is found only in plant cells.
• C. The rough ER is involved in lipid synthesis, while the smooth ER is involved in protein synthesis.
• D. The rough ER is responsible for detoxification processes, while the smooth ER is not.

Answer: (A)

Verified step by step guidance

1. Begin by understanding the structure and function of the endoplasmic reticulum (ER) in eukaryotic cells. The ER is a network of membranous tubules and sacs that plays a crucial role in the synthesis and transport of proteins and lipids.
2. Identify the two types of ER: rough ER and smooth ER. The rough ER is characterized by the presence of ribosomes on its surface, giving it a 'rough' appearance under a microscope. The smooth ER lacks these ribosomes, hence its 'smooth' appearance.
3. Explore the functions of the rough ER. The ribosomes attached to the rough ER are sites of protein synthesis. As proteins are synthesized, they are threaded into the lumen of the rough ER where they undergo folding and modification.
4. Examine the functions of the smooth ER. Unlike the rough ER, the smooth ER is involved in lipid synthesis, metabolism of carbohydrates, detoxification of drugs and poisons, and storage of calcium ions.
5. Clarify the misconception that the rough ER is found only in animal cells and the smooth ER only in plant cells. Both types of ER are present in eukaryotic cells, including both plant and animal cells, serving distinct but complementary roles.