Which organelle is involved in lipid synthesis and detoxification of chemicals, and lacks ribosomes on its surface?

• A. Rough ER
• B. Smooth ER
• C. Golgi apparatus
• D. Lysosome

Answer: (B)

The smooth endoplasmic reticulum handles lipid synthesis and detoxification. It makes phospholipids and cholesterol needed for membranes, and uses enzymes to modify and detoxify chemicals, such as drugs. Its surface is smooth because it lacks ribosomes, which are the sites of protein synthesis on the rough ER. This combination of lipid-building function and detoxification capability, together with the absence of ribosomes, distinguishes it from other organelles. The rough ER has ribosomes and focuses on protein production, the Golgi apparatus processes and packages those proteins and lipids, and lysosomes break down waste materials. Hence, the organelle described is the smooth endoplasmic reticulum.