What does incomplete dominance refer to

Mendel did not study incomplete dominance because the pea plant does not show any incomplete dominance intermediate traits. These results show the Law of inheritance where alleles are inherited from parents to offspring still occurs in the incomplete dominance described by Mendel.

In research on quantitative genetics, the possibility for incomplete dominance requires the resulting phenotype to be partially related to any of the genotypes homozygotes ; otherwise, there will be no dominance. Codominance refers to the dominance in which the two alleles or traits of the genotypes of both homozygotes are expressed together in offspring phenotype.

There is neither a dominant nor recessive allele in cross-breeding. Rather the two alleles remain present and formed as a mixture of both of the alleles that each allele has the tendency to add phenotypic expression during the breeding process. In some cases, the codominance is also referred to as no dominance due to the appearance of both alleles of homozygotes in the offspring heterozygote. Thus, the phenotype produced is distinctive from the genotypes of the homozygotes.

The upper case letters are used with several superscripts to distinguish the codominant alleles while expressing them in writings. This writing style indicates that each allele can express even in the presence of other alleles alternative. The example of codominance can be seen in plants with white color as recessive allele and red color as dominant allele produce flowers with pink and white color spots after cross-breeding.

However, further research revealed the codominance in plants and vice versa. The genotypic ratio was the same as Mendel described. They produced offspring that results in the F1 generation to include red, spotted white and pink , and white with the same genotypic ratio. Codominance can be easily found in plants and animals because of color differentiation, as well as in humans to some extinct, such as blood type.

The incomplete dominance produces offspring with intermediate traits whereas the codominance involves the mixing of allelic expressions. However, in both types of dominance, the parent alleles remain in the heterozygote. Nonetheless, no allele is dominant over the other.

Incomplete dominance is a widely studied phenomenon in genetics that leads to morphological and physiological variations. The pink flower color trait, which is an example of incomplete dominance, occurs in nature, such as those found in pink-flower-bearing angiosperms. Apart from plants, incomplete dominance also occurs in animals and humans. For example, hair color, eye color, and skin color traits are determined by multiple alleles in humans.

Take a look at the examples below for the incomplete dominance in plants, humans, and other animals. The Carnation plant which is an example of incomplete dominance has true-breeding white flowers and true-breeding red flowers.

A cross between white- and red-flowering carnation plants may result in offspring with a phenotype of pink flowers. Red and white flowering plants breed to produce offspring with pink color flowers. Snapdragon also shows incomplete dominance by producing pink-colored snapdragon flowers. The cross-pollination between red and white snapdragons leads to pink color flowers because none of the alleles white and red is dominant.

Incomplete dominance is used to improve corn crops as the partially dominating traits of corn are generally high yielding and healthier than original ones with fewer traits. In plants, the self-sterility n is an example of multiple alleles that causes the rapid growth of pollen tubes. Despite the concept of adaptation of incomplete dominance by humans in genetics to increase better living, incomplete dominance can also be seen in humans genetically.

The crossing of two different alleles in the genetic process produces human offspring either with different or intermediate forms between the two traits. Thus, it can be said that incomplete dominance is as old as a human life that leads to variation with time.

Most of the physical characteristics of humans, including hairs, eye color, height, skin color, sound pitch, and hand sizes, show incomplete dominance. Children born with semi-curly or wavy hair are an example of individuals exhibiting incomplete dominance because the crossing of parents alleles both straight and curly hairs to produce such offspring. Thus, incomplete dominance occurs to produce an intermediate trait between the two parent traits.

The eye color of humans is a more common example of incomplete dominance. However, understanding incomplete dominance for eye color is quite complicated. Human height patterns also show incomplete dominance. Human skin color is another example of incomplete dominance because the genes that produce the melanin pigment for either dark or light skin cannot show dominance over the other.

Thus, the offspring produced have an intermediate skin color between the parents. Usually, male humans have high-pitched sound, and other homozygotes have reduced sound pitches. Another example of incomplete dominance is the inheritance of straight, wavy, and curly hair in dogs. The KRT71 gene is used to synthesize the keratin 71 protein. Genes in the KRT family provide instructions for making proteins called keratins. Keratins are a group of tough, fibrous proteins that form the structural framework of epithelial cells, which are cells that line the surfaces and cavities of the body.

Epithelial cells make up tissues such as the hair, skin, and nails. These cells also line the internal organs and are an important part of many glands. Keratins are best known for providing strength and resilience to cells that form the hair, skin, and nails. These proteins allow tissues to resist damage from friction and minor trauma, such as rubbing and scratching. Keratins are also involved in several other critical cell functions, including cell movement migration , regulation of cell size, cell growth and division proliferation , wound healing, and transport of materials within cells.

Different combinations of keratin proteins are found in different tissues. Search for: 'incomplete dominance' in Oxford Reference ». All Rights Reserved. Under the terms of the licence agreement, an individual user may print out a PDF of a single entry from a reference work in OR for personal use for details see Privacy Policy and Legal Notice. Oxford Reference.

Publications Pages Publications Pages. Recently viewed 0 Save Search. Your current browser may not support copying via this button. Incomplete Dominance in Plants The science of genetics began with plants. Incomplete dominance was first recorded in plants. The German scientist Josef Kolreuter bred red and white carnations, expecting to get offspring with the dominant red coloration.

Instead, many came up pink! Kolreuter found that neither allele was fully dominant in his flowers and identified the concept of incomplete dominance. Four-o-clocks are flowering plants that get their funny name from their inclination to bloom in the late afternoon.

Wild four-o-clocks tend to have red flowers, while "pure" four-o-clocks with no coloration genes are white. Mixing the two results in pink flowers, just like Dr.

Kolreuter's carnations. Those pink flowers are a result of incomplete dominance. That ratio - a quarter like one parent, a quarter like the other, and the remaining half different from either - is common in cases of incomplete dominance.

Pink snapdragons are a result of incomplete dominance. Cross-pollination between red snapdragons and white snapdragons result in pink when neither the white or the red alleles are dominant. The fruit color of eggplants is another example of incomplete dominance. Combining deep purple eggplants with white eggplants results in eggplants of a light violet color.

Incomplete dominance is a key element of improving crops such as corn. Corn with multiple incompletely dominant traits is generally healthier and provides greater yields than "purer" strains with fewer such traits.