Advanced Placement (AP) Biology Practice Exam

What organelle is responsible for modifying, sorting, and packaging materials into vesicles?

1. Ribosome

2. Chloroplast

3. Golgi apparatus

4. Lysosome

The correct answer is: Golgi apparatus

The Golgi apparatus is the organelle responsible for modifying, sorting, and packaging proteins and other materials into vesicles. It functions like a processing and shipping center within the cell. After proteins are synthesized in the endoplasmic reticulum, they are transported to the Golgi apparatus, where they undergo chemical modifications, such as glycosylation. This modification process is crucial for the proper functioning of proteins as it helps determine their destinations and functionalities. Once the proteins are appropriately processed, the Golgi apparatus sorts them and packages them into vesicles that transport these materials to their final destinations, which could be within the cell or to the cell membrane for export. This organelle plays an essential role in cell communication and the maintenance of cellular functions by ensuring the proper distribution of biomolecules. Understanding the specific roles of other organelles is also beneficial. Ribosomes are primarily involved in protein synthesis, while chloroplasts are responsible for photosynthesis in plant cells. Lysosomes function as the cell's waste disposal system, breaking down unwanted materials. In contrast, the Golgi apparatus directly contributes to the modification and distribution of key cellular materials. Therefore, its specialized functions are essential for maintaining cellular organization and activity.