Incomplete dominance

From WikiMD's Wellness Encyclopedia

Incomplete Dominance is a genetic phenomenon where neither of the two versions of a gene is completely dominant over the other. This results in a third phenotype, where the expressed physical trait is a combination of the phenotypes of both alleles. Unlike complete dominance where one allele is completely dominant over the other, incomplete dominance results in a phenotype that is a mixture of the parent phenotypes.

Overview[edit | edit source]

Incomplete dominance occurs when the phenotype of the heterozygous genotype is distinct from and often intermediate to the phenotypes of the homozygous genotypes. For example, if a white flowered plant (WW) is crossed with a red flowered plant (RR), the offspring will be pink (WR).

Examples[edit | edit source]

One classic example of incomplete dominance is the color of the snapdragon flower. When a red-flowered snapdragon (RR) is crossed with a white-flowered snapdragon (WW), the result is not a red or white flower, but a pink snapdragon (WR).

Another example is found in certain breeds of chickens. When a chicken with black feathers (BB) is crossed with a chicken with white feathers (WW), the resulting offspring have a coloration described as blue (BW).

Genetic Basis[edit | edit source]

The genetic basis of incomplete dominance is related to the inability of one allele to produce enough functional protein to exhibit a dominant phenotype. This can occur if the dominant allele is a loss-of-function allele, or if the protein it produces is not fully functional.

See Also[edit | edit source]

References[edit | edit source]


Incomplete dominance Resources
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Contributors: Prab R. Tumpati, MD