|LYSOSOMES... are a cells' digestive organelles. They degrade injested materials, as a bacterium taken in by phagocytosis. The bacterium is fused with primary lysosomes vesicles containing hydrolytic enzymes. An H+ATPase makes the pH more acidic activating the enzymes. The vesicle thus becomes a secondary lysosome and degrades the bacterium.
Lysosomes also degrade worn out organelles, as mitochondria. A section of rough E.R. wraps itself around a mitochondrion & forms a vacuole. Then, lysosomal enzyme vesicles fuse with the vacuole making it becomes an active secondary lysosome.
A third function for lysosomes is to handle the products of receptor-mediated endocytosis. The early coalescence of vesicles bringing in the receptor or ligand produce an endosome. The introduction of lysosomal enzymes and the lower pH causes degradation & release of the contents.
Lysosomes hold hydrolases, active at an acid pH, that degade nucleotides, proteins, lipids, phospholipids, and also remove carbohydrate, sulfate, or phosphate groups from molecules. A Hydrogen ion ATPase is found in the membrane of lysosomes to acidify the environment.