Where are proteins manufactured within a cell?

Proteins are primarily manufactured within a cell at the ribosomes. Ribosomes are complex molecular machines made up of ribosomal RNA and proteins that facilitate the translation of messenger RNA (mRNA) into a polypeptide chain, which then folds into a functional protein. This process occurs in the cytoplasm of the cell, either freely floating or attached to the endoplasmic reticulum, which is known as rough ER when ribosomes are bound to it.

The other cellular components mentioned have distinct functions. The Golgi apparatus is involved in modifying, sorting, and packaging proteins for secretion or delivery to other organelles but does not synthesize them. Mitochondria are the powerhouse of the cell and generate energy through cellular respiration, while the nucleus houses the cell's genetic material and is where transcription occurs, not the actual synthesis of proteins. Hence, the ribosome is accurately identified as the site of protein synthesis in the cell.