What organelle modifies, sorts, and packages proteins and lipids?

The Golgi apparatus is the organelle responsible for modifying, sorting, and packaging proteins and lipids for secretion or for use within the cell. It acts like a post office, receiving proteins and lipids from the endoplasmic reticulum, where they undergo several modifications, such as glycosylation. After these modifications, the Golgi apparatus sorts the molecules and packages them into vesicles that can be transported to their final destinations, whether that's outside the cell, to the cell membrane, or to other organelles. This process is crucial for the proper functioning of cells, as proteins and lipids are essential for a myriad of cellular functions, including structural integrity, communication, and metabolism.

The nucleus, while crucial for storing genetic information and overseeing cellular activities, does not engage in the modification and sorting of proteins and lipids. Mitochondria primarily focus on energy production through cellular respiration, and the endoplasmic reticulum is involved in the synthesis of proteins and lipids rather than their modification and sorting. Therefore, the Golgi apparatus stands out as the key organelle for these specific functions in protein and lipid processing.