Question

The punnett square below shows the genotypes for offspring produced from a cross between a red cow and a white bull. if all of the offspring have roan coats—white hairs mixed into a base coat of red—what can be said about the red and white alleles for coat color?

Answer 1

They are codominant.

Answer 2

Answer:

Red and white alleles are codominant

Explanation:

Gregor Mendel discovered a pattern of inheritance in which one allele masks the expression of its variant pair in a gene i.e. it is expressed over it. He called the allele that masks, DOMINANT allele while the allele being masked, RECESSIVE allele. However, genetic cases of inheritance has occurred that proved this Law of Dominance, to not always be the case.

In the scenario whereby the two involved alleles show neither dominance or recessiveness to one another i.e. no allele is dominant or recessive. Instead, both alleles combine in the resulting heterozygotic offspring to be expressed simultaneously. In essence, both alleles get expressed in the heterozygous individual. This is known as CODOMINANCE.

This example given in the question is the case, where the red allele is neither dominant nor recessive over the white allele and vice versa. Hence, they produce a hybrid cattle with roan coat, which is a mixture of red and white allele both expressed at the same time.