Lysosome
A lysosome is a special type of vesicle (which are fluid-filled sacs surrounded by membrane). They are produced by the golgi apparatus and contain hydrolytic enzymes which can digest materials. Lysosomes can digest anything from invading bacteria to the cell's own damaged organelles. Sometimes they even release their digestive enzymes into the cell and digest the cell itself (this is called apoptosis, when the cell is programmed to die at a certain point).
The contents of the lysosome is acidic (pH ~ 5). In order to achieve this acidity when the surrounding cytoplasm is roughly neutral, the lysosome has proton pumps which move hydrogen ions from the cytoplasm into the lysosome. When it is digesting food in a vesicle/vacuole, its membrane fuses with the membrane of the food vesicle and the digestive enzymes break down the food. On the other hand, when it is digesting something that's not enclosed within a vesicle, the lysosome simply engulfs it. In short, lysosomes digest most proteins, fats, sugars, and nucleic acids. |