Which structure is involved in protein synthesis within a cell?

The correct answer, ribosome, plays a crucial role in the process of protein synthesis within a cell. Ribosomes are complex molecular machines made up of ribosomal RNA and proteins. They can be found free-floating in the cytoplasm or attached to the endoplasmic reticulum, creating what is known as rough ER.

During protein synthesis, ribosomes facilitate the translation of messenger RNA (mRNA) into a polypeptide chain, which eventually folds into a functional protein. The ribosome reads the codons on the mRNA sequence and matches them to the appropriate transfer RNA (tRNA) that carries specific amino acids. This process is essential for the expression of genes into functional proteins that perform a multitude of tasks in the cell, from structural components to enzymes.

The other structures mentioned, while important for various cellular functions, do not directly engage in the synthesis of proteins. The Golgi apparatus, for example, is primarily involved in modifying, sorting, and packaging proteins for secretion or delivery to other organelles. Vesicles are small membrane-bound sacs that transport materials within the cell but do not synthesize proteins. Lysosomes contain enzymes that digest cellular waste and macromolecules but are not involved in assembling amino acids into proteins.