Question

why is oncogenic mutation dominant and why is tumor suppressor mutation recessive?

Answer 1

Oncogenic mutation are the mutation in preoncogenes to form oncogenes. Product of oncogenes stimulate the rapid divison and stops the differentiation and mutation in one copy us suffucient to stimulate the divison continously.

But in case of tumour supressor genes the both copy should be mutated so that no product is available for suppression of cell divison. Hence mutation are recessive. And presence of one normal copy cant sufficient to nullify the supression effect.