Question

Female cattle that have white coats are crossed with male cattle that have red coats. Both male and female offspring have roan coats, which are coats with both red hairs and white hairs.Which of the following best describes the genetics of coat color in the cattle?
A The red and white alleles are sex-linked.
B The red and white alleles are codominant.
C The red allele is recessive to the white allele.
D The red allele is dominant to the white allele.

Answer 1

A The red and white alleles are sex-linked.

Answer 2

Answer:

B (The red and white alleles are codominant)

Explanation:

Co-dominance is a relationship between two versions of a gene in which neither allele is recessive (masked) nor dominant, the phenotypes of both alleles are expressed.

Ideally, an individual organism receives one form of a gene, called allele, from each parent i.e. It possesses two alleles. If the alleles are different, one will usually be expressed while the other masked in accordance to Mendel's law of dominance. The expressed allele is called the DOMINANT allele while the masked allele is called the RECESSIVE allele.

But in co-dominance, a genetic scenario occurs in which no allele is masked, both are simultaneously expressed in the resulting heterozygotic offspring. Hence, the phenotype of the offspring is a combination of the phenotypes of the parents.

In this case involving a cross between a female cattle with white coat and a male one with red coat, an heterozygotic offspring with roan coat is produced. The roan coat is a combination of the red and white coat phenotype i.e. Both white and red alleles are manifesting the phenotypes and are said to be codominant

Note that, neither the red or white allele is recessive nor dominant over one another.