1. What is incomplete dominance? What is codominance?
The phenomenon of incomplete dominance has been a concept that specifies that a genetic situation where intermediate inheritance is obtained by any species where there is the presence of a dominant allele is represented as a form of a gene. The phenomenon of incomplete dominance occurs when the dominant allele fails to completely overpower the recessive allele. This results to the appearance of an organism that is mostly found to be an intermediate state between the dominant allele and the recessive allele. The physical appearance of the organisms appears to have both the influence of the dominant allele and the recessive allele. Thus, the incomplete dominance can be regarded as the genetic situation where the dominant allele and the recessive allele both appear in the physical specification of an organism forming a new genetic characteristic consisting both the characteristic of the dominant allele and the recessive allele. This phenomenon is a rare occurrence but it is not much of the rarest occasions that the dominant allele cannot overpower the recessive allele and an intermediate characteristic is depicted on the physical characteristic of the offspring organism.
On the other hand, according to the genetic science, codominance is identified as a factor that establishes the relationship between two versions of a gene. Mostly, an organism receives a version of a gene from their parent organism. The versions of the genes are known as an allele. The allele is transferred from the parent to the child organism. When the alleles appear to be different than each other, then it is found that the dominant allele is being replicated on the child organism. Where the recessive allele and its characteristics will be masked in the child while being transferred from the parent organism. When it occurs that the organism has received the genes from both the parents but neither of them have been translated to the offspring organism. Rather than having the physical attributes that describes the dominant or the recessive characteristic, the offspring organism would have a completely different attribute that would be described by the phenomenon of codominance. If it is seen that the parent organisms are having the physical characteristics that are completely different from each other comprising of the dominant allele and the recessive allele, then in the phenomenon of codominance, neither of the allele would be reflected on the offspring organism, rather it would not have the concept of a recessive or a dominant allele and the phenotypes that would be reflected on the offspring organism would be containing both the alleles expressed on their physical characteristics. Therefore, it would mean that in the codominance state, neither of the allele would be able to mask the physical characteristic or the expression of the other allele. Rather than having one allele being dominant on the other, the properties of both the alleles from the parent organization would be evidently present in the physical characteristic of the child offspring without one of them being dominant on each other or vice versa.
2. Examples of Incomplete Dominance and Codominance?
Examples for Incomplete Dominance: The phenomenon and occurrences of Incomplete Dominance is found in all kinds of species consisting a genetic structure and those who are able to reproduce. The following section would have the examples of the incomplete dominance based on the occurrences of the phenomenon of incomplete dominance on all kinds of organisms that have the ability of displaying genetic characteristics. As for example, in case of the humans, the child that is born to the parent having different kinds of skin colour may represent by being born with the skin colour that is neither the skin colour of the father or the mother. If the father is found to possess a dark skin colour and the mother is found to possess a light skin colour, the child may appear to have the combination of the dark and the light skin. In this case, neither the dark skin or the light skin is found to be dominant or recessive on one another, and instead, the child would have the physical characteristic of both the parents.
The phenomenon of the incomplete dominance is also seen within the human organisms that mostly have been found to be the carriers of the Tay-Sachs diseases. These human organisms have been identified to lack the enzyme that helps in the breaking down of lipids. This causes the accumulation of too many amounts of the lipids in the brain and various other areas in the nervous system. Thus, the disease leads to the deterioration of the nervous system and this also results further to development of loss in the mental and physical abilities of a human body. The disease is a formation of the accumulation of two different kinds of recessive alleles. This is such case where the people carrying one of the recessive alleles do not show any symptoms of the disease as they would be dormant in the person as a recessive allele. However, these people would also be producing half of the normal amount of the enzymes and would display a phenotype that is an intermediate between the presence of the disorder and the absence of the disorder.
The phenomenon of incomplete dominance is also seen to be occurring in other forms of animals, for example, a chicken. There is a special species of chicken that is represented by the name Andalusian chicken mostly found in Spain. These chickens are found to be showing the incomplete dominance based in the colour of the feather it possesses. When a white male chicken and a black female chicken is found to be producing an offspring, then the offspring might be having a feather that has blue tinges on it. This occurs due to the dilution genes that happens to dilute the melanin pigment in the feathers partially and produces a lighter coloured feather.
Example of Codominance: It might occur that the organisms, for example the breed of chickens has the phenomenon of codominance occurring in them. It might happen that the chicken with white colour feathers and the chicken with the black coloured feather are producing an offspring that appears to have both black and white feathers at once. It can also happen in several species of red cattle breeds. It might Orchid that when a red cattle meets with another thread cattle the offspring may have both Red and White hairs which is a mixed coat pattern known as roan and this pattern would be evident in identifying that the phenotypes of both the alleles are present in the offspring. In some kinds of rhododendron plants as well the exhibition of codominance can be found. It may be a cross breed between the red and white flowers that would have the gilded flower describing both the red and white patches. There are occurrences of many flowers that similarly show the patterns of codominance where the parental flower considering different colours show up in various parts of the plant and not the flowers.
In another example, where codominance occurs is the blood type of humans. The genes contain three different version of proteins that appear on the outer layer of the blood cells helping to identify the cells as the owns known as the alleles A, B and O. This is because there lies three different version of the gene proteins and the allele O does not really code with any protein at all and therefore lacks both the proteins A and B. When a person inherits the A allele from one parent and the allele B from another parent, it may result to the formation of AB blood type, which would be resulting to the visualisation of codominance.
3. Summary: What is the difference between incomplete dominance and codominance?
The primary difference between incomplete dominance and codominance lies in the genetic traits or alleles that mostly provides the phenotype produced with the mixture of dominant and recessive alleles in the offspring of any species. It is found that when both the alleles are present in the offspring which is a complete mixture of the dominant and recessive ones coming from the parents it is known as incomplete dominance. Where on the other hand codominance is a phenomenon that is a specific trait that expresses the characteristics of both the alleles equally in the offspring. The resulting cyanotype mostly expresses the characters of both the parent and the mixture of their characteristics. The traits that the offspring game from their parents are inherited with the transfer of genes and the segments of DNA that are located within the chromosomes. This DNA Sar pass from one generation to the other and therefore usually the condition of dominance is not present in incomplete dominance but for codominance both the characteristic traits are fully dominant. The effect of the incomplete dominance in the organisms are found through the blend of both the characteristics were one of the two is more noticeable then the other but on the other side for codominance both the characteristic traits equally blended together to show equal effects or sometimes produced and sometimes produce new characteristics trait.