Final answer:
A lysosome is a specialized vacuole that carries digestive enzymes for processes like fat digestion, cellular recycling, and immune defense through phagocytosis.
Step-by-step explanation:
The specialized vacuole full of digestive enzymes used in fat digestion, materials recycling, and defense is known as a lysosome. Lysosomes are organelles that contain around 40 different hydrolytic enzymes such as lipases, proteases, and nucleases that break down various organic polymers. These enzymes help in digesting fats (lipids), proteins, nucleic acids, and even damaged organelles. In the cellular process known as autophagy, lysosomes digest the cell's own components, acting like a cellular 'recycling center'. Moreover, lysosomes are crucial in the defense system, specifically by the action of white blood cells like macrophages which use phagocytosis to engulf and destroy pathogens with the help of the lysosomal enzymes.