Which organelle is responsible for protein synthesis?

• A. Nucleus
• B. Lysosome
• C. Ribosome
• D. Golgi

Answer: (C)

Protein synthesis is carried out at ribosomes, the cellular machines that translate mRNA into proteins. They read the genetic message carried by mRNA and, with tRNAs bringing the appropriate amino acids, stitch them together in the correct order to form a polypeptide. Ribosomes can be free in the cytoplasm or attached to the rough endoplasmic reticulum, reflecting where the newly made protein will be used or exported. The nucleus houses DNA and is the site of transcription to make mRNA, but the actual assembly of amino acids happens on ribosomes, not inside the nucleus. Lysosomes digest waste and recycle materials, while the Golgi apparatus modifies, sorts, and packages proteins after synthesis. So the organelle responsible for protein synthesis is the ribosome.