To cause cancer, tumor suppressor genes require allele(s) to be mutated and therefore are considered The mutation results in a of function.
The correct answer and explanation is :
To cause cancer, tumor suppressor genes require both alleles to be mutated and therefore are considered recessive. The mutation results in a loss of function.
Explanation:
Tumor suppressor genes are critical regulators of cell growth and division. They function to prevent uncontrolled cell proliferation, repair DNA damage, and trigger apoptosis (programmed cell death) when necessary. Examples of tumor suppressor genes include TP53, RB1, and BRCA1/BRCA2.
For a tumor suppressor gene to contribute to cancer, both copies (alleles) of the gene must be mutated or inactivated. This concept is known as the “two-hit hypothesis,” proposed by Alfred Knudson. The first mutation (or “hit”) is often inherited (as seen in familial cancer syndromes like hereditary retinoblastoma), while the second mutation occurs spontaneously in somatic cells.
Because one functional copy of a tumor suppressor gene is usually sufficient to regulate cell division, a single mutation (one hit) does not typically cause cancer. However, when both alleles are mutated or lost, the gene can no longer perform its protective role, leading to uncontrolled cell growth and tumor formation. This makes tumor suppressor gene mutations recessive at the cellular level, meaning that loss of function only occurs when both copies are defective.
In contrast, oncogenes (another class of cancer-related genes) require only a single allele to be mutated to promote cancer, making them dominant at the cellular level.
In summary, tumor suppressor genes require both alleles to be mutated to lose function, making them recessive cancer-related genes. Their inactivation leads to uncontrolled cell division and contributes to tumor development.