Which cellular structure builds proteins by linking amino acids together?

Which cellular structure builds proteins by linking amino acids together?

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

Answer: (A)

Proteins are built at the ribosome, the cellular machine that links amino acids together to form a growing polypeptide chain. It works by translating the genetic message carried by messenger RNA and bringing in the correct amino acids via transfer RNAs, then forming peptide bonds between them. This is the core step of translating DNA instructions into functional proteins, and ribosomes can be free in the cytoplasm or bound to the rough endoplasmic reticulum in eukaryotic cells. The other structures have different roles. The nucleus stores DNA and is where transcription happens to make mRNA, but the actual linking of amino acids occurs later at the ribosome. The mitochondrion is primarily involved in energy production, with some specialized protein synthesis, but it is not the main site where proteins are assembled by linking amino acids. The Golgi apparatus processes, sorts, and ships proteins after they are made, not the place where they are assembled.

Proteins are built at the ribosome, the cellular machine that links amino acids together to form a growing polypeptide chain. It works by translating the genetic message carried by messenger RNA and bringing in the correct amino acids via transfer RNAs, then forming peptide bonds between them. This is the core step of translating DNA instructions into functional proteins, and ribosomes can be free in the cytoplasm or bound to the rough endoplasmic reticulum in eukaryotic cells.

The other structures have different roles. The nucleus stores DNA and is where transcription happens to make mRNA, but the actual linking of amino acids occurs later at the ribosome. The mitochondrion is primarily involved in energy production, with some specialized protein synthesis, but it is not the main site where proteins are assembled by linking amino acids. The Golgi apparatus processes, sorts, and ships proteins after they are made, not the place where they are assembled.