1. Nucleus: The "brain" of the cell. It contains the cell's genetic material (DNA) in the form of chromosomes. The nucleus controls all cellular activities, including growth, metabolism, and reproduction.

2. Mitochondria: The "powerhouses" of the cell. They are responsible for generating energy (ATP) through cellular respiration, using oxygen and glucose to produce energy that the cell can use.

3. Golgi apparatus: The "packaging and shipping" center of the cell. It receives proteins and lipids from the endoplasmic reticulum, modifies them, and packages them into vesicles for transport to other parts of the cell or for secretion outside the cell.