Cell Division and Cancer Practice Exam 2025 – Your All-in-One Guide to Mastering Cell Biology and Oncology!

Tumor suppressor genes are crucial in regulating cell division and maintaining genomic integrity. These genes work by producing proteins that prevent uncontrolled cell growth. In normal circumstances, an individual has two copies of each gene, one inherited from each parent. For cancer to potentially develop as a result of mutations in tumor suppressor genes, both alleles of the gene need to be mutated.

When one allele is mutated, it may lead to a loss of function, but the second, healthy allele can still produce the necessary protein to regulate the cell cycle and prevent tumor formation. It is only when the second allele is also mutated or lost (in cases such as deletion) that there is a complete loss of the tumor suppressor function. This is often referred to as the “two-hit hypothesis,” which suggests that both alleles must be inactivated for tumorigenesis to occur.

Thus, the correct answer highlights that two mutated alleles of a tumor suppressor gene are required to contribute to the potential development of cancer.