Final answer:
Organelles are membrane-bound structures within eukaryotic cells with specific functions. Three types of organelles are the endoplasmic reticulum, the Golgi apparatus, and vesicles, which all participate in the endomembrane system responsible for producing, packaging, and exporting cellular materials.
Step-by-step explanation:
An organelle is a specialized structure within the cytoplasm of a eukaryotic cell that is enclosed within a membrane and performs a specific function, similar to the organs in our body. Three types of organelles that play key roles in cellular function are the endoplasmic reticulum (ER), Golgi apparatus, and vesicles. These organelles are part of the endomembrane system, which is crucial for producing, packaging, and exporting cellular products. The ER provides channels for transporting and synthesizing materials and is connected to the nuclear membrane. The Golgi apparatus further processes and packages proteins and lipids into vesicles, which then transport these substances to their destination inside or outside the cell.