In which cellular structure are proteins primarily manufactured?

In which cellular structure are proteins primarily manufactured?

• A. Nucleus
• B. Mitochondria
• C. Golgi apparatus
• D. Ribosomes

Answer: (D)

Proteins are built by ribosomes, the cell’s protein-synthesis machines. They translate the genetic message in mRNA into amino acids, linking them into polypeptide chains. Ribosomes can be free in the cytosol or attached to the rough endoplasmic reticulum, the latter producing proteins destined for secretion or membranes. The nucleus contains DNA and is where transcription begins but not where proteins are assembled. Mitochondria have their own ribosomes and can make a small subset of proteins, but most cellular proteins are synthesized by cytosolic ribosomes. The Golgi apparatus then modifies, sorts, and ships these proteins after synthesis. So the primary site of protein manufacture is the ribosome.

Proteins are built by ribosomes, the cell’s protein-synthesis machines. They translate the genetic message in mRNA into amino acids, linking them into polypeptide chains. Ribosomes can be free in the cytosol or attached to the rough endoplasmic reticulum, the latter producing proteins destined for secretion or membranes. The nucleus contains DNA and is where transcription begins but not where proteins are assembled. Mitochondria have their own ribosomes and can make a small subset of proteins, but most cellular proteins are synthesized by cytosolic ribosomes. The Golgi apparatus then modifies, sorts, and ships these proteins after synthesis. So the primary site of protein manufacture is the ribosome.