What is the role of ribosomes in the cell?

• A. They are the molecular machines where protein synthesis occurs, translating mRNA into polypeptide chains.
• B. They store genetic information.
• C. They regulate the cell cycle.
• D. They produce ATP directly.

Answer: (A)

Protein synthesis is carried out by ribosomes, the cellular machines that translate the genetic message in mRNA into a growing polypeptide chain. They read mRNA codons and recruit the appropriate aminoacyl-tRNA molecules, linking amino acids together via peptide bonds to form a protein. This translation process is aided by ribosomal RNA and proteins, and the ribosome can be free in the cytoplasm or attached to the rough endoplasmic reticulum, depending on where the protein will go. Ribosomes don’t store genetic information—that’s DNA—and they don’t directly generate ATP—that power comes mainly from mitochondria—nor do they control the cell cycle. So their role is to convert the mRNA sequence into a functional protein by translating the genetic code into a specific sequence of amino acids.