Section 2: Codominance

Front

What is codominance?

Back

Codominance is a genetic scenario where both alleles in a heterozygous organism contribute equally and visibly to the organism's phenotype.

Front

Give an example of codominance in animals.

Back

An example of codominance in animals is the roan coat color in cattle, where both red and white fur colors are expressed.

Front

What is the genotype for a calico cat?

Back

The genotype for a calico cat is typically X^OX^B, where X^O represents the orange allele and X^B represents the black allele.

Front

What is the phenotypic ratio of a roan cow mating with a roan steer?

Back

The phenotypic ratio is 1 Red : 2 Roan : 1 White.

Front

What are the genotypes for red and white flowers in codominance?

Back

Red flowers are C^RC^R and white flowers are C^WC^W.

Front

What is the phenotype of a flower with the genotype C^BC^R?

Back

The phenotype of a flower with the genotype C^BC^R is red/blue speckled.

Front

What is the expected phenotypic ratio when crossing a red flower with a speckled flower?

Back

The expected phenotypic ratio is 2:2 or 1:1 (red:speckled).

Front

Define incomplete dominance.

Back

Incomplete dominance is a genetic situation where the phenotype of a heterozygote is intermediate between the phenotypes of the two homozygotes.

Front

What is the difference between codominance and incomplete dominance?

Back

In codominance, both alleles are fully expressed, while in incomplete dominance, the phenotype is a blend of the two alleles.

Front

What does the term 'allele' mean?

Back

An allele is a variant form of a gene that can produce different traits.