Eye colour is not controlled by a single gene, it is a combination of different genes that will ultimately dictate your eye colour. To understand this, we will first consider one of the genes involved. There are two alleles for this one gene, either 'blue' or 'not blue' eyes. A person who inherits a 'blue' allele from both parents will have blue eyes, ie we say that their phenotype (how they appear)is blue. A person who inherits a 'blue' allele from one parent and a 'not blue' allele from the other will have a phenotype (appearance)of 'not blue' eyes because 'not blue' is dominant over 'blue'. Then we must consider another gene that is involved. if you inherit 'not blue' eye colour then this other gene that you inherit will kick in and give your eyes some colour. A small amount of colour (melanin pigment) will make your eyes grey. More and more of this pigment can make them green, then hazel and then brown. eg - A blue eyed man (both his parents therefore must have had blue eyes) , married to a brown eyed woman (who had one parent 'blue' and the other 'not blue') could have children with blue, grey, green, hazel or brown eyes.
- Some "alleles" (hereditary traits) are dominant, and others are recessive. - If a pure dominant trait is bred with a recessive trait, their offspring will show 75% presence of the dominant trait, and 25% presence of the recessive trait in the F1 (first filial) generation. - If a plant with a dominant trait from the F1 generation (carrier, heterozygous dominant) is bred with a plant that shows a recessive trait, their offspring will display at 50/50 probability of dominance versus recessiveness. Thus, alleles expressing a particular trait via dominance/recessiveness, in the case of the pea plants, take the form of two alleles that combine to express a particular version. This later has been shown to be homozygous dominance/recessiveness, or heterozygous dominance.
When a red flower crosses with a white flower, it can create a pink flower. Why? Because of incomplete dominance. Incomplete dominance is when the heterozygous phenotype(offspring) is a blend of the two homozygous phenotypes(parents).
You get aspects of each trait displayed. Like, if one cat had a solid colored orange fur, and it's mate was brown, you could get a mottled cat. Or if one parent has brown eyes, and the other green, hazel eyes could occur.
This is an example of incomplete dominance.
offspring
The principle of dominance and recessiveness explains why the offspring is albino. Albinism is a recessive trait, meaning that both parents must carry at least one copy of the albino gene in order for it to be expressed in the offspring. This demonstrates how traits can be masked in one generation and expressed in the next through Mendelian genetics.
Incomplete dominance can create offspring that display a trait not identical to either parent but intermediate to the two. One example of incomplete dominance is a red flower and a white flower crossbreed to form a pink flower.
The proportions of the two phenotypes in the F1 generation remained constant as the number of offspring increased from 10 to 100. This is because the inheritance of traits follows Mendelian principles, and the ratio of phenotypes will only change if there is an assortment such as independent segregation.
The offspring will likely exhibit the tall phenotype due to the dominance of the tall allele. The genotype of the offspring would be TtRr, with a combination of dominant and recessive alleles for both height and seed shape. This type of cross would result in a 9:3:3:1 ratio of phenotypes in the offspring according to Mendelian genetics.
Incomplete dominance, where the heterozygous phenotype is an intermediate blend of the two homozygous phenotypes.
The possible genotypes of the offspring are Bb (heterozygous blue) and bb (white). The possible phenotypes are blue and white flowers. Each offspring will inherit one allele from each parent, resulting in a 50% chance of being blue (Bb) and 50% chance of being white (bb).
Incomplete dominance occurs when neither allele is completely dominant over the other, resulting in a blending of traits in the offspring. This means that the phenotype of the heterozygous individual is a mix of the phenotypes of the two homozygous parents.
A pattern of inheritance that the blending hypothesis fails to explain is incomplete dominance, where the heterozygous phenotype is intermediate between the two homozygous phenotypes. This contradicts the blending hypothesis, which suggests that the traits of the parents are mixed together in the offspring. In incomplete dominance, the traits remain distinct in the offspring.
The diagram can be used to predict the genotypes and phenotypes of offspring by following the inheritance patterns of the parents' traits. By analyzing the alleles passed down from each parent, one can determine the possible combinations of genotypes and corresponding phenotypes that the offspring may inherit.
- Some "alleles" (hereditary traits) are dominant, and others are recessive. - If a pure dominant trait is bred with a recessive trait, their offspring will show 75% presence of the dominant trait, and 25% presence of the recessive trait in the F1 (first filial) generation. - If a plant with a dominant trait from the F1 generation (carrier, heterozygous dominant) is bred with a plant that shows a recessive trait, their offspring will display at 50/50 probability of dominance versus recessiveness. Thus, alleles expressing a particular trait via dominance/recessiveness, in the case of the pea plants, take the form of two alleles that combine to express a particular version. This later has been shown to be homozygous dominance/recessiveness, or heterozygous dominance.
Incomplete dominance is shown in this scenario, where the offspring have a phenotype that is a blend of the two parent phenotypes. In this case, the heterozygous pink flowering plants are the result of incomplete dominance of the red and white flower alleles.
Both alleles are expressed in offspring when neither allele is dominant over the other, resulting in co-dominance. This means that both alleles are simultaneously expressed in the offspring's phenotype.