Final answer:
The intrinsic apoptotic pathway is initiated by the tumor suppressor protein p53, which monitors the integrity of the cell's DNA.
Step-by-step explanation:
The intrinsic apoptotic pathway is a process that leads to programmed cell death, or apoptosis. It is initiated by the tumor suppressor protein p53 in response to DNA damage or other cellular stressors. The p53 protein serves as a checkpoint to monitor the integrity of the cell's DNA. If damage is detected, p53 activates the transcription of genes involved in DNA repair, and if repair is unsuccessful, it triggers apoptosis.
During the intrinsic apoptotic pathway, p53 activates the expression of pro-apoptotic proteins, such as Bax and Bak. These proteins promote the permeabilization of the outer mitochondrial membrane, allowing the release of cytochrome C into the cytoplasm. Cytochrome C then forms a complex with other molecules, leading to the activation of caspases, which are protease enzymes that initiate the dismantling of the cell.
In summary, p53 acts as a guardian of the cell's genome, ensuring that damaged cells are either repaired or eliminated through apoptosis to prevent the development of cancer. The intrinsic apoptotic pathway is a crucial mechanism in maintaining cellular homeostasis and eliminating cells that are no longer needed or potentially harmful.