Final answer:
Cancer occurs when the cell cycle loses control. Two genes that may cause cancer are proto-oncogenes and tumor-suppressor genes. 50% of tumors have inactivated tumor-suppressor genes and hyperexpressed proto-oncogenes.
Step-by-step explanation:
Cancer occurs when the cell cycle loses control. Two genes that may cause cancer are proto-oncogenes and tumor-suppressor genes. 50% of tumors have inactivated tumor-suppressor genes and hyperexpressed proto-oncogenes. Cancer occurs when the cell cycle is disrupted, allowing cells with damaged DNA to divide uncontrollably. Two key types of genes often implicated in this process are tumor-suppressor genes and proto-oncogenes. Tumor-suppressor genes normally prevent the division of cells with damaged DNA, but mutations in these genes can lead to their inactivation, allowing damaged cells to proliferate. Conversely, proto-oncogenes normally help regulate cell division, yet their mutation can create oncogenes which then promote the division of damaged cells. For example, 50% of tumors have inactivated the tumor-suppressor gene known as TP53, which plays a crucial role in cell cycle control and apoptosis, and hyperexpressed MYC, an oncogene that when overexpressed leads to uncontrolled cell proliferation. Misregulation of these genes can drive the transformation of normal cells into cancerous cells, contributing to tumor development and progression.