Here's why:

* Specialized subunit: Organelles are distinct structures within a cell that have unique roles.

* Specific function: Each organelle performs a specific task, contributing to the overall function of the cell.

* Separately enclosed within its own lipid membrane: Most organelles are surrounded by a membrane that separates them from the rest of the cell's cytoplasm. This allows them to maintain a distinct internal environment and carry out their specific functions.

Examples of organelles:

* Mitochondria: Powerhouse of the cell, responsible for energy production.

* Golgi apparatus: Modifies, sorts, and packages proteins.

* Endoplasmic reticulum: Involved in protein synthesis and lipid metabolism.

* Lysosomes: Digest waste materials and cellular debris.

* Nucleus: Contains the cell's genetic material (DNA).

Let me know if you have any other questions!