Final answer:
The Golgi apparatus consists of a stack with different regions through which proteins and lipids from the ER are modified by Golgi enzymes and then sent to the plasma membrane or other cell destinations.
Step-by-step explanation:
The Golgi apparatus plays a crucial role in modifying, sorting, and packaging proteins and lipids that are received from the endoplasmic reticulum (ER). The transition of materials from the ER to the Golgi and then to the plasma membrane involves a stack of membranous cisternae with four functional regions: the cis-Golgi network, medial-Golgi, endo-Golgi, and trans-Golgi network. As vesicles from the ER fuse with the cis-Golgi network, they pass through these regions in the mentioned order.
During this journey, Golgi enzymes within each region uniquely modify proteins by glycosylation or phosphorylation which helps in determining their final destinations, such as lysosomes and incorporation into the plasma membrane. The trans face of the Golgi apparatus is the exit point where repackaged vesicles are sent to their appropriate destinations, including fusion with the plasma membrane for secretion of certain materials outside the cell.