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

The Golgi apparatus is the organelle primarily responsible for the modification, sorting, and transport of proteins that are synthesized in the endoplasmic reticulum. Once proteins are produced by ribosomes on the rough endoplasmic reticulum, they are transported to the Golgi apparatus. Here, they undergo post-translational modifications, such as the addition of carbohydrates (glycosylation) or the formation of disulfide bonds, which are essential for the proper functioning of proteins. After modification, the Golgi apparatus packages these proteins into vesicles that can then be transported to their designated destinations within or outside the cell.

Other organelles play distinct roles: ribosomes are critical for protein synthesis, lysosomes contain enzymes for breaking down waste materials and cellular debris, and the nucleus houses the genetic material and is the site of transcription. Each of these organelles has a specific function that complements the overall processes of cell biology, but it is the Golgi apparatus that uniquely excels in the modification and transportation of proteins.