Lysosomes are organelles containing digestive enzymes (acid hydrolases). They're found in animal cells, while in plant cells the same roles are performed by the vacuole. They digest excess or worn-out organelles, food particles, and engulfed viruses or bacteria. The membrane surrounding a lysosome allows the digestive enzymes to work at the 4.5 pH they require. Lysosomes fuse with vacuoles and dispense their enzymes into the vacuoles, digesting their contents. They're created by the addition of… (More on Lysosome)