Gene mutations can be positive negative or neutral suppose that the normal gene in model 2 produces a polypeptide that was necessary for cellular respiration

Mutations are the source of all new alleles. An allele is a variant form of a gene. Variations in alleles lead to variations in organisms. Positive mutations give an organism a better chance of survival. It means that the mutation may be passed on to the offspring. Negative mutations may lead to an early death. Therefore, changes in alleles from one generation to another form the basis of evolution.