In some cases it can be difficult to distinguish between co-dominance and incomp

Question

In some cases it can be difficult to distinguish between co-dominance and incomplete dominance using genetic crosses.

Our discussion in class referred to a diploid species where flower color was coded by a single locus where AA=red, aa=white and Aa=pink. The pink color could be caused by only a half of red pigment in heterozygotes (dose effect), or because the presence of red and white pigment gives pink (co-dominance).

Things would get much easier if, instead of a diploid plant, we were using a tetraploid plant. In that case, AAAA=red, aaaa=white, AAaa=pink. In 200 words or fewer, describe how you could use genetic crosses to distinguish between co-dominance vs. dose effect. In the case of co-dominance, assume that the amount of pigment produced by an allele is independent from the number of alleles present.

Explanation / Answer

Codominance is closely related to incomplete dominance in this both alleles are simultaneously expressed in the heterozygote. There will be no mixing of the effect of the two alleles both are alleles produce their effect independently.

In codominance the recessive and dominant traits appeared together in the phenotype of hybrid organisms.

Here in a given example when redt plans are crossed with white plants the entire generation will be pink colour flowers which is neither like the dominant parents. Both the dominant allele coexist and express both phenotypes.

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