Most mutations in a diploid organism are recessive. Why?

Key Concepts

Diploid Organisms

Diploid organisms have two sets of chromosomes, one inherited from each parent. This means that for any given gene, there are two alleles present. The interaction between these alleles determines the organism's phenotype, with dominant alleles masking the effects of recessive ones.

Recessive Mutations

Recessive mutations occur when a change in the DNA sequence leads to a non-functional protein or no protein at all. For a recessive mutation to manifest in the phenotype, both alleles of the gene must carry the mutation. This is why many mutations are considered recessive, as the presence of a dominant allele can mask their effects.

Dominance and Phenotype Expression

Dominance refers to the relationship between alleles, where a dominant allele can mask the expression of a recessive allele in a heterozygous individual. This means that if one allele is dominant, the phenotype will reflect that dominant trait, while the recessive trait will only be expressed when both alleles are recessive, explaining why most mutations are recessive in diploid organisms.