Final answer:
Apoptosis, or programmed cell death, is crucial for tissue development and maintenance, as it ensures the removal of damaged or unnecessary cells, and balances cell death with cell proliferation for tissue renewal. It is regulated by internal and external signals and involves key proteins like Bak and Bax. Faulty apoptosis can lead to diseases such as cancer.
Step-by-step explanation:
Apoptosis, or programmed cell death, is a process that allows cells to die in a controlled manner. This cellular mechanism is essential for normal tissue development and maintenance. When cells are lost from healthy tissues, they are typically replaced with new cells. This replacement occurs through a balance of cell death and cell proliferation. During development, apoptosis is crucial for shaping structures, such as the elimination of interdigital webbing in vertebrates, allowing separated fingers and toes to form. For immune cells like T-cells, apoptosis ensures that cells that mistakenly recognize self-proteins are removed to prevent autoimmune diseases. Unregulated cell division, in contrast, can lead to tumorigenesis when apoptotic mechanisms fail to clear damaged or genetically mutated cells.