Final answer:
P53, when detecting extensive DNA damage, triggers major pro-apoptotic genes, such as Bax, to induce apoptosis. This response prevents the propagation of cells with DNA errors, acting as a defense against cancer.
Step-by-step explanation:
When extensive DNA damage is detected, the tumor suppressor protein p53 activates major pro-apoptotic genes to induce apoptosis, or programmed cell death.
This is a crucial function of p53 as it acts as a guardian of the genome, ensuring that cells with irreparable DNA damage do not continue to divide and propagate mutations.
When p53 is mutated, it loses its ability to trigger apoptosis, which can lead to unregulated cell proliferation and cancer development.
The activation of pro-apoptotic genes by p53 can involve several genes, but one of the major genes triggered is Bax, which promotes apoptosis by disrupting the mitochondrial membrane potential, leading to the release of cytochrome c and activation of caspases.
As the levels of p53 rise in response to stress, it also halts the cell cycle by triggering the production of p21, which inhibits cell cycle progression further reinforcing the cell's response to DNA damage.