Which organelle is the primary site of protein synthesis?

Which organelle is the primary site of protein synthesis?

• A. Ribosome
• B. Mitochondrion
• C. Golgi Apparatus
• D. Lysosome

Answer: (A)

Protein synthesis happens at the ribosome, the molecular machine that reads mRNA and assembles amino acids into a polypeptide. The ribosome can float freely in the cytosol, making soluble cytosolic proteins, or attach to the rough endoplasmic reticulum to produce proteins destined for secretion or membranes. Other organelles have different roles: mitochondria are mainly energy producers and have their own ribosomes for a small subset of proteins, the Golgi apparatus handles modification and shipment of proteins after synthesis, and lysosomes break down waste. So, the primary site where the bulk of protein synthesis occurs is the ribosome.

Protein synthesis happens at the ribosome, the molecular machine that reads mRNA and assembles amino acids into a polypeptide. The ribosome can float freely in the cytosol, making soluble cytosolic proteins, or attach to the rough endoplasmic reticulum to produce proteins destined for secretion or membranes. Other organelles have different roles: mitochondria are mainly energy producers and have their own ribosomes for a small subset of proteins, the Golgi apparatus handles modification and shipment of proteins after synthesis, and lysosomes break down waste. So, the primary site where the bulk of protein synthesis occurs is the ribosome.