Unicellular microorganisms that undergo asexual reproduction (exemple: bacteria, yeast, etc.)
Each mutation is hereditary, i.e. transmitted to daughter cells.
Multicellular organisms that undergo sexual reproduction
Mutations in germinal stem cells : hereditary mutations are transmitted to offspring via the gametes.
Somatic cell mutation: the abnormal phenotype is non-transmittable, and the mutation is lost upon the death of the organism.