Which structure makes ribosomes?

• A. Endoplasmic Reticulum
• B. Nucleolus
• C. Vacuole
• D. Chloroplast

Answer: (B)

Ribosome production happens in the nucleolus, a dense region inside the nucleus. There, genes that encode ribosomal RNA are transcribed and processed, and ribosomal proteins imported from the cytoplasm assemble with the rRNA to form the small and large ribosomal subunits. These subunits are then exported to the cytoplasm to join into functional ribosomes that carry out protein synthesis. The endoplasmic reticulum hosts ribosomes for protein production but does not create ribosomes itself; vacuoles are storage compartments, and chloroplasts have their own ribosomes for organelle-specific protein synthesis but not for building the cell’s ribosomes.