1. Nucleus: The control center of the cell, containing DNA and directing protein synthesis.

2. Mitochondria: Powerhouses of the cell, responsible for generating energy (ATP) through cellular respiration.

3. Endoplasmic Reticulum (ER): A network of membranes involved in protein synthesis (rough ER) and lipid synthesis (smooth ER).

4. Golgi Apparatus: A series of flattened sacs responsible for modifying, sorting, and packaging proteins and lipids for transport within or outside the cell.