Which cellular structure is crucial for protein assembly?

Ribosomes are essential for protein assembly because they are the cellular structures responsible for translating messenger RNA (mRNA) into polypeptide chains, which then fold into functional proteins. Ribosomes can be found either free-floating in the cytoplasm or attached to the endoplasmic reticulum, forming rough endoplasmic reticulum. During translation, ribosomes read the sequence of nucleotides in mRNA and use the genetic code to assemble amino acids in the correct order to create proteins. This process is fundamental to all cellular activities, as proteins play critical roles in structure, function, and regulation within the cell.

The other structures mentioned serve different purposes. Mitochondria are involved in energy production through cellular respiration, while the nucleus houses genetic material and is responsible for gene expression regulation. The Golgi apparatus functions in processing and packaging proteins for secretion or delivery to other organelles. While all these structures are vital to cell function, ribosomes are specifically dedicated to the assembly of proteins.