Final answer:
A cell with inactivated TP53 alleles cannot produce functional p53, essential for detecting damaged DNA and initiating repair or apoptosis. This deficiency leads to unregulated cell division, accumulation of mutations, and potential cancer development.
Step-by-step explanation:
When a cell that is carrying damaged DNA has both of its TP53 alleles inactivated, several significant events occur that can lead to cancer. The TP53 gene codes for the p53 protein, which serves as a crucial tumor suppressor and plays a major role in preventing uncontrolled cell growth. A cell with inactive TP53 alleles cannot produce functional p53 to initiate DNA repair, block the cell cycle or trigger apoptosis (programmed cell death) in the presence of DNA damage. Consequently, the cell might continue to divide without repairing the damaged DNA, leading to the accumulation of further mutations and the potential development of cancer.
Without p53 acting as a guardian of the genome at the G1 checkpoint, the cell bypasses critical regulatory mechanisms, allowing for unregulated proliferation. This unchecked division can result in the formation of tumor cells with both oncogenes and non-functional tumor suppressor genes, which can form a malignant tumor. Hence, the inactivation of TP53 alleles in a cell carrying damaged DNA leads to a lack of genetic integrity required for controlled growth, and if left unchecked, this contributes to tumor growth and cancer development.