Final answer:
Apoptosis is the process of programmed cell death involving regulatory proteins, such as P53 and the Bcl2 family. It is crucial in development and preventing autoimmune diseases by eliminating cells recognizing self proteins or web-like tissues between digits. The process also controls virally infected cells, preventing the spread of infection.
Step-by-step explanation:
Apoptosis, also known as programmed cell death, plays a critical role in development and immune system regulation by eliminating damaged or unnecessary cells. There are various mechanisms by which apoptosis can be induced in a cell, including when a cell is infected by a virus or when it is damaged. Such conditions trigger the apoptotic process to help maintain cellular homeostasis and prevent abnormal cell proliferation, which could lead to diseases such as cancer.
An example of an external signal leading to apoptosis is seen during T-cell development, where cells that incorrectly recognize self proteins undergo apoptosis to prevent autoimmune diseases. Morphogenesis, such as the development of fingers and toes, also involves apoptosis to remove web-like tissues between digits. Furthermore, proteins such as P53 and the Bcl2 family, including Bak and Bax, are involved in apoptosis regulation. These proteins participate in mitochondrial membrane permeabilization, leading to cytochrome C release and activation of caspases, which are proteases that dismantle the cell from within. Additionally, fas ligand molecules on cytotoxic T cells induce apoptosis in other cells by binding to fas receptors.
Given that apoptotic mechanisms are particularly effective against virally infected cells by preventing the release of infectious viruses, understanding and manipulating these pathways are significant for therapies against viral diseases and cancer.