Which organelle has ribosomes on its surface and assists in protein synthesis?

• A. Golgi apparatus
• B. Lysosome
• C. Rough Endoplasmic Reticulum
• D. Mitochondrion

Answer: (C)

Ribosomes attached to a membrane-heavy organelle point to a site where proteins are synthesized and prepared for export or insertion into membranes. The rough endoplasmic reticulum has ribosomes studding its surface, so it’s the site where these ribosomes translate mRNA into polypeptides that are then threaded into the ER lumen for folding and modification. This setup explains why it’s tied to protein synthesis and processing for secretion or membrane localization. Other organelles don’t fit this role: the Golgi apparatus handles further processing and shipping of proteins but isn’t a primary site of ribosome-studded synthesis; lysosomes are specialized for breakdown; mitochondria contain their own ribosomes inside the organelle and focus on energy production, not on proteins synthesized on a membrane-bound surface.