Final answer:
The transformation of normal cells into cancer cells is typically caused by the mutation of proto-oncogenes into oncogenes, leading to uncontrolled cell division. This disruption in cell cycle regulation can result in the formation of tumors and the development of cancer.
Step-by-step explanation:
The scenario that transforms normal cells into cancer cells involves the mutation of proto-oncogenes into oncogenes. Proto-oncogenes normally regulate cell cycle progression by producing proteins that signal the cell to divide. However, when these genes are mutated, they can become oncogenes, which cause an increase in the rate of cell cycle progression, leading to uncontrolled and rapid cell division. This can result in the formation of a tumor and potentially cancer. Conversely, tumor suppressor genes work to inhibit the cell cycle and promote repair or apoptosis in the case of DNA damage. When tumor suppressor genes are mutated and lose their function, cell cycle progression is less restricted, contributing to the same outcome: excessive cell proliferation.
Mutations in these genes disrupt the normal balance of cell division and can lead to cancer. Proto-oncogenes become oncogenes often as a result of mutations that either increase the amount or activity of the protein product, leading to unregulated cell growth. This is in contrast to tumor suppressor genes, which when mutated, fail to appropriately regulate the cell cycle and prevent the division of cells with damaged DNA.