Question

In cattle, codominance of the allele for a red coat (R) and the allele for a white coat (W) results in offspring with a roan coat (RW); that is, a coat with both red and white hairs.

Cross a roan cow and a roan bull. What are the genotype and phenotype ratios of their offspring?

Answer 1

Genotype ratio: 1 (RR) : 2 (RW) : 1 (WW)

Phenotype ratio: 1 Red : 2 Roan : 1 White

Step-by-step explanation:

Codominance is a kind of inheritance pattern in which both alleles are equally dominant in a gene. This means that both alleles when in a heterozygous state will be simultaneously expressed. According to this question, allele for a red coat (R) and the allele for a white coat (W) results in offspring with a roan coat (RW) in cattle.

Hence, in a cross between a a roan cow (RW) and a roan bull (RW), the following gametes will be produced: R and W.

Using these gametes in a punnet square (see attached image), the offsprings with the following genotypes will be produced: RR, RW, RW, WW.

Therefore, based on the results of the cross;

Genotype ratio: 1 (RR) : 2 (RW) : 1 (WW)

Phenotype ratio: 1 Red : 2 Roan : 1 White