Which organelle is known as the 'protein factory' of the cell?

• A. Nucleus
• B. Endoplasmic reticulum
• C. Ribosomes
• D. Golgi apparatus

Answer: (C)

Ribosomes are the protein factory. They read the genetic message carried by mRNA and link together amino acids to form polypeptides, the building blocks of proteins. In cells, ribosomes can float freely in the cytosol or be attached to the rough endoplasmic reticulum, giving that surface its “rough” appearance. The nucleus stores DNA and makes RNA, but it doesn’t assemble proteins directly. The Golgi apparatus then modifies and packages the proteins for transport, and the endoplasmic reticulum helps with protein folding and processing. Because ribosomes are the actual sites where proteins are synthesized, they earn the label protein factory.