Microbiology Practice Exam

Ribosomes play a crucial role in protein synthesis within both prokaryotic and eukaryotic cells. They are the cellular machinery responsible for translating messenger RNA (mRNA) into polypeptide chains, which then fold into functional proteins. This process occurs in the cytoplasm, where ribosomes can either be free-floating or bound to the endoplasmic reticulum in eukaryotic cells.

During protein synthesis, ribosomes read the sequence of codons in the mRNA and facilitate the assembly of amino acids in the correct order, which is determined by the genetic code. This fundamental process is essential for cellular function since proteins serve as enzymes, structural components, signaling molecules, and play various other roles in the cell.

The other functions listed, such as DNA replication, cell division, and energy production, are performed by different cellular components or processes and do not involve ribosomes directly. Thus, the primary biological function of ribosomes is indeed protein synthesis, making this choice the correct one.