Final answer:
Tumor-suppressor genes can behave in a dominant or recessive manner. In general, they are recessive alleles, but certain mutations can exhibit dominant negative effects. Mutated alleles of the p53 gene, for example, can behave dominantly and are associated with many human cancers.
Step-by-step explanation:
Tumor-suppressor genes can behave in a dominant or recessive manner, depending on the specific mutation. In general, tumor-suppressor genes are recessive alleles, as they require mutations in both copies of the gene to render them non-functional. However, there are instances when one mutated allele of a tumor-suppressor gene can have a dominant negative effect, rendering the other copy non-functional. This means that even though the normal copy of the gene is present, the mutant copy overrides its function.
For example, mutated alleles of the p53 gene, a well-known tumor-suppressor gene, can behave dominantly. Mutations in the p53 gene are associated with many human cancers. In individuals with a mutated p53 allele, there is a ~100% lifetime risk of cancer. The mutated p53 allele can lead to unregulated cell proliferation and suppression of apoptosis, exhibiting characteristics of cancer cells.
Overall, the behavior of mutated alleles of tumor-suppressor genes can vary, and it depends on the specific gene and mutation involved.