Which organelle is responsible for lipid synthesis?

• A. Golgi apparatus
• B. Ribosomes
• C. Nucleus
• D. Smooth ER

Answer: (D)

Lipid synthesis occurs mainly in the smooth endoplasmic reticulum. This part of the cell lacks ribosomes on its surface, and its membranes host the enzymes that build fatty acids into phospholipids and cholesterol, which are essential components of cellular membranes and various signaling molecules. In contrast, the rough endoplasmic reticulum is studded with ribosomes and is specialized for protein synthesis, while the Golgi apparatus handles the processing, modification, and packaging of lipids and proteins after they’re made. The nucleus stores genetic material and isn’t involved in lipid production. So, the smooth endoplasmic reticulum is the organelle most directly responsible for lipid synthesis.