Question

Just for fun, imagine that “shirt-striping” is a phenotypic character caused by a single gene. Construct a genetic explanation for the appearance of the family in the above photograph, consistent with their “shirt phenotypes.” Include in your answer the presumed allele combinations for “shirt-striping” in each family member. Identify the inheritance pattern shown by the child.

Short answer

The father possesses genes that code for horizontal stripes, while the mother possesses genes for vertical stripes. In contrast, the child possesses gene copies of both horizontal and vertical stripes as it has checked stripes.

S^Hs or S^HS^Hmust be the genotype for horizontal stripes, and S^Ws or S^wS^w must be the genotype for vertical stripes, and S^HS^Wmust be the genotype for checked stripes.

The inheritance observed in the child is co-dominance as it exhibits traits of both the parents.

Step-by-step solution

Explanation for the phenotype “shirt stripping”

In the picture, the father has horizontal shirt striping; he possesses genes for horizontal stripes. The mother has vertical shirt stripping, which means she possesses genes for vertical stripes.

The child has checked shirt stripping, which means he has inherited both horizontal and vertical alleles from father and mother, respectively.

Genotypes of all the members of the family

Let S^Hbe the allele for horizontal stripes, S^W be the allele for vertical stripes, and s be the allele that does not code for any stripes. Here, S^Hand S^W are dominant over the s allele. Then, the genotype of the father must be S^Hs or S^HS^H, and the genotype of the mother must be S^Ws or S^wS^w.

The checked shirt pattern of the child results from the inheritance of horizontal stripes from the father and vertical stripes from the mother. This means he possesses both the traits of mother and father.

Thus, the genotype of the child must be S^HS^W. This indicates both S^H and S^W are co-dominant alleles.

Inheritance pattern of shirt striping

Co-dominance is an inheritance pattern where both the traits are expressed equally in the offspring. It results from the inheritance of alleles from father and mother that are equally expressed.

As observed in the picture, the stripes in the child have resulted from the inheritance of horizontal trait from the father and vertical trait from the motherthat results in the formation of the checked pattern.

Thus, the checked pattern observed in the child is an example of co-dominance.