Eukaryotes have a number of membrane-bound compartments that are used for a variety of purposes. One such compartment is the lysosome . Lysosomes are involved in breaking down materials in the cell. When vesicles bud off of the plasma membrane, bringing contents from outside the cell into the cytoplasm, they first fuse with lysosomes. Special hydrolytic enzymes (enzymes that hydrolyze/breakdown molecules) within lysosomes degrade material within the vesicles. The hydrolytic enzymes are initially synthesized in an inactive state, and only upon reaching the lysosome do they become activated. Because the active hydrolytic enzymes are compartmentalized within the lysosomes, only material within the lysosomes is degraded.