Which cell organelle is known as the 'suicide bag' of the cell?

Lysosomes are small, round, membrane-bound sacs found in the cytoplasm of animal cells (they are rare in plant cells). They were discovered by the Belgian scientist Christian de Duve in 1955, who received the Nobel Prize in Physiology or Medicine in 1974.

Lysosomes contain powerful digestive (hydrolytic) enzymes, such as lipases, proteases and nucleases, which can break down proteins, fats, carbohydrates and nucleic acids. These enzymes work best in an acidic environment (pH about 4.5-5), which is kept inside the lysosome. Lysosomes are formed by the Golgi apparatus, and their enzymes are made on the rough endoplasmic reticulum.

Lysosomes have several functions:

Intracellular digestion: they digest food particles and foreign materials, such as bacteria taken into the cell. White blood cells use lysosomes to destroy germs.

Autophagy: they break down worn-out and damaged organelles, keeping the cell clean. For this, they are also called the "waste disposal system" or "scavengers" of the cell.

Autolysis: when a cell is old or badly damaged, the lysosome membrane may burst, and the enzymes digest the cell itself. This is why lysosomes are called "suicide bags".

Defects in lysosomal enzymes cause lysosomal storage diseases, such as Tay-Sachs disease, in which undigested substances build up in cells. The Japanese scientist Yoshinori Ohsumi received the Nobel Prize in 2016 for his work on autophagy.

Why not the other options?

• ✗Ribosomes make proteins and are called the "protein factories" of the cell.
• ✗The Golgi apparatus packages and dispatches materials and is called the "post office" or "traffic police" of the cell.
• ✗Mitochondria are the "powerhouses" of the cell.