Where does all protein synthesis occur in the cell?

Protein synthesis is a fundamental cellular process that occurs in the cytosol, where ribosomes translate messenger RNA (mRNA) into polypeptide chains, ultimately folding into functional proteins. This process involves the formation of peptide bonds between amino acids as dictated by the sequence of codons on the mRNA.

While the endoplasmic reticulum is involved in the post-translational modification and trafficking of proteins, and the Golgi apparatus further modifies and sorts proteins, the actual synthesis—where the ribosomal translation of mRNA into amino acid sequences occurs—primarily takes place in the cytosol.

The nucleus serves a different function in protein synthesis, primarily roles such as transcription of DNA into mRNA and processing the mRNA before it is translated. Hence, the cytosol is the correct and primary location for all protein synthesis within the cell.