Lysosomes

Lysosomes were discovered by Christian de Duve in 1953, and their nickname - 'suicidal bags' - hints at exactly what makes them potentially dangerous to the cell that contains them. Structurally, a lysosome is a fairly simple, spherical body enclosed by a single unit membrane, found only in eukaryotic cells, and it forms when small fragments pinch off from the tubules of the Golgi body. What makes a lysosome distinctive is its cargo: it is packed with a wide variety of hydrolytic enzymes, capable of breaking down (digesting) essentially any of the major biological macromolecules found within a cell. The single membrane surrounding the lysosome is what keeps these powerful enzymes safely contained, preventing them from leaking out and digesting the cell's own healthy structures. Functionally, lysosomes serve several distinct roles. In intracellular digestion, they break down carbohydrates, proteins and lipids present in the cytoplasm. In autophagy, under adverse conditions, they turn that same digestive capacity inward and break down the cell's own organelles, such as mitochondria and endoplasmic reticulum, recycling their components. In controlled autolysis, on receiving a signal of disease or damage, lysosomes can trigger the self-destruction of the entire cell they belong to. In ageing, the slow, ongoing action of lysosomal autolytic enzymes gradually disrupting intracellular molecules is thought to contribute to cellular decline over time. In phagocytosis, when large particles or whole cells are engulfed by …