Which organelle is responsible for synthesizing proteins?

The rough endoplasmic reticulum (Rough ER) is the organelle responsible for synthesizing proteins due to the presence of ribosomes on its cytoplasmic surface. These ribosomes are the sites of protein translation, where messenger RNA (mRNA) is read to assemble amino acids into polypeptide chains, ultimately forming proteins. The Rough ER facilitates the proper folding and post-translational modifications of these newly synthesized proteins, preparing them for their respective functions or for transport to other parts of the cell.

In contrast, the smooth endoplasmic reticulum lacks ribosomes and is primarily involved in lipid synthesis and detoxification processes. Mitochondria are the powerhouse of the cell, primarily responsible for ATP production through cellular respiration. Lysosomes contain digestive enzymes that break down waste materials and cellular debris, rather than synthesizing proteins. This highlights the specialized roles of each organelle within cellular biology.