Question

Summarize the events of apoptosis.

Short answer

The major events that occur in apoptosis include cell contraction, fragmentation of cells, disintegration of the cytoskeleton, followed by nuclear envelope degradation, and finally the release of apoptotic bodies by the cells.

Step-by-step solution

Apoptosis

Apoptosis is a physiological process that occurs during development and is necessary for an animal's defense and maintenance. It is commonly known as programmed cell death.

It is defined as a process in which cells die naturally and in a controlled manner as part of an organism's growth and development. Tadpoles, for example, lose their tails when they mature into adults due to apoptosis.

Events occurring in apoptosis

Apoptosis begins with a cell that appears to be healthy losing intercellular connections, which leads to cell shrinkage. At the nuclear periphery, the chromatin condenses, the cytoskeleton distingrates, and the nuclear envelop collapses. The DNA of the cell is fragmented and the plasma membrane blebs.

At the end, the parts of the cell are packaged into numerous membrane-enclosed apoptotic bodies that are engulfed by wandering macrophages and adjacent cells. During this process, the content of the cells is not leaked to prevent the generation of an inflammatory response.

The phospholipid phosphatidylserine, which is present on the outer leaflet of apoptotic cells and acts as a signal for being phagocytized, is used by phagocytic cells to recognize apoptotic cells.

Hence, DNA and the organelles of the cell fragment, the cell shrinks and produces blebs, and finally the parts of cells are packaged in vesicles to be consumed by phagocytic cells during apoptosis.