Lysosome are cellular organelles that contain acid hydrolase enzymes that break down waste materials and cellular debris. They can be described as the stomach of the cell. They are found in animal cells, while their existence in yeasts and plants is disputed. Some biologists say the same roles are performed 의해 lytic vacuoles, while others suggest there is strong evidence that lysosomes are indeed found in some plant cells. Lysosomes digest excess 또는 worn-out organelles, 음식 particles, and engulf viruses 또는 bacteria. The membrane around a lysosome allows the digestive enzymes to work at the pH they require. Lysosomes fuse with autophagic vacuoles and dispense their enzymes into the autophagic vacuoles, digesting their contents. The name lysosome derives from the Greek words lysis, to separate, and soma, body. They are frequently nicknamed "suicide-bags" 또는 "suicide-sacs" 의해 cell biologists due to their autolysis. Lysosomes were discovered 의해 the Belgian cytologist Christian de Duve in 1949. A group of genetic inherited disorders called lysosomal storage diseases (LSD) results from the dysfunction of lysosomes. The size of a lysosome varies from 0.1–1.2 μm. At pH 4.8, the interior of the lysosomes is acidic compared to the slightly basic cytosol (pH 7.2). The lysosome maintains this pH differential 의해 pumping protons (H+ ions) from the cytosol across the membrane via proton pumps and chloride ion channels. The lysosomal membrane protects the cytosol, and therefore the rest of the cell, from the degradative enzymes within the lysosome. The cell is additionally protected from any lysosomal acid hydrolases that drain into the cytosol, as these enzymes are pH-sensitive and do not function well 또는 at all in the alkaline environment of the cytosol.This ensures that cytosolic molecules and organelles are not lysed in case there is leakage of the hydrolytic enzymes from the lysosome. Lysosomes are the cell's waste disposal system and can digest some compounds. They are used for the digestion of macromolecules from phagocytosis (ingestion of other dying cells 또는 larger extracellular material, like foreign invading microbes), endocytosis (where receptor proteins are recycled from the cell surface), and autophagy (wherein old 또는 unneeded organelles 또는 proteins, 또는 microbes that have invaded the cytoplasm are delivered to the lysosome). Other functions include digesting bacteria (or other forms of waste) that invade a cell and helping repair damage to the plasma membrane 의해 serving as a membrane patch, sealing the wound. In the past, lysosomes were thought to kill cells that are no longer wanted, such as those in the tails of tadpoles 또는 in the web from the fingers of a 3- to 6-month-old fetus.