Which organelle is associated with synthesis of lipids and processing of proteins?

• A. Ribosomes
• B. Lysosomes
• C. Endoplasmic Reticulum
• D. Golgi apparatus

Answer: (C)

Endoplasmic reticulum handles both lipid synthesis and protein processing. The rough ER has ribosomes on its surface, so it’s the site where newly made proteins enter the ER lumen to be folded, assembled, and post-translationally modified before moving on to the Golgi. The smooth ER, lacking ribosomes, specializes in lipid synthesis, including phospholipids and cholesterol, and also participates in detoxification processes. This combination of lipid production and protein maturation is why this organelle is the best choice for the described roles. Ribosomes synthesize proteins but don’t handle lipids; lysosomes break down waste; the Golgi modifies and sorts proteins but is not the primary site of lipid synthesis.