Question

Why are tumor suppressor gene mutations recessive while oncogene mutations are dominant?

Answer 1

Ans ) Tumor suppressor Genes :- These are normal genes which slow down cell division, repair DNA mistakes, or tell cells when to die.These genes generally follow the methodology of two-hit hypothesis, which states both alleles that code for a particular protein must be affected before an effect is manifested. If only one allele for the gene is damaged, the other can still produce enough of the correct protein to retain the appropriate function.

In other words, mutant tumor suppressor alleles are usually recessive ,whereas mutant oncogene alleles are typically dominant.In tumor suppressors it is loss-of-function mutations that contribute to the progression of cancer. This means that tumor suppressor mutations tend to be recessive, and thus both alleles must be mutated in order to allow abnormal growth to proceed.

Tumor-suppressor genes :- They encode proteins that in one way or another inhibit cell proliferation.Since generally one copy of a tumor-suppressor gene suffices to control cell proliferation, both alleles of a tumor-suppressor gene must be lost or inactivated in order to promote tumor development. Thus oncogenic loss-of-function mutations in tumor-suppressor genes act recessively.