Active Transport

ATP (Adenosine Triphosphate): This is often referred to as "molecular currency" for intracellular energy transfer; it transports chemical energy within cells for metabolism.

Endocytosis: A type of active transport where cells absorb material from outside by engulfing it with their cell membrane.

Exocytosis: Another type of active transport where cells expel waste materials or secretory products by vesicles fusing with plasma membrane and releasing their contents outside the cell.