Which organelle is primarily involved in the modification and sorting of proteins?

The Golgi apparatus is the organelle primarily responsible for the modification and sorting of proteins. After proteins are synthesized by ribosomes, they enter the endoplasmic reticulum (ER), where they undergo initial folding and modification. From the ER, these proteins are transported to the Golgi apparatus, where they receive further modifications, such as glycosylation (addition of sugar molecules) and phosphorylation (addition of phosphate groups).

Once the proteins have been modified, the Golgi apparatus sorts and packages them into vesicles for delivery to their final destinations, which could be within the cell or secretion outside the cell. This central role in processing proteins makes the Golgi apparatus a critical hub in the cellular workflow for protein handling, ensuring that proteins are correctly modified and sent to where they are needed.

In contrast, the mitochondria are primarily involved in energy production through cellular respiration, while ribosomes are the sites of protein synthesis. Lysosomes contain digestive enzymes for breaking down waste materials and cellular debris. Therefore, the specific function of the Golgi apparatus in modifying and sorting proteins underscores its importance in protein processing within the cell.