Apoptosis: The Biological Recycling Protocol

Large Cellular Trauma

When large scale DNA damage is detected within cells, a protein detects the threat and initiates a signaling cascade (image below) which activates a series of proteins that begin breaking down the cytoskeleton, initiating apoptosis. Slowly, the cell begins to lose its shape and disintegrates into several membrane bound “blobs”. Enzymes break down the complex proteins within these vesicles and, eventually, the vesicles themselves. The resulting macro-molecule fragments are taken up by functioning cells and used as needed.

In the same way, a cell can be instructed from outside to trigger the same process. This process is executed by the immune system. When a cell is infected, it informs the body of its condition by placing pathogenic protein fragments known as antigens on its surface. These signals are picked up by white blood cells that ultimately result in the immune system killing off the infected cell. The spots that occur on your skin during chicken pox is a good example of this; each spot contains the debris of a war between millions of cells and virus particles.

However, cellular biology is never so simple. The process of apoptosis is closely mirrored by another mechanism known as autophagy. Autophagy is another way for the body to recycle broken down parts. We can follow this process with an analogy: