When a trait shows codominant alleles, both alleles are expressed equally in the phenotype of the organism. Here's a breakdown:

Codominance Explained:

* Alleles: Alternative forms of a gene.

* Codominance: A pattern of inheritance where both alleles contribute to the phenotype. This means both alleles are "dominant" and expressed simultaneously.

Example: Blood Type

A classic example is the ABO blood group system in humans.

* Alleles: There are three alleles: I^A, I^B, and i.

* Codominance: Both I^A and I^B are codominant. If an individual inherits both I^A and I^B alleles, their blood type is AB. This means their red blood cells express both A and B antigens, resulting in a distinct blood type.

Characteristics of Codominance:

* Both Alleles Expressed: Unlike incomplete dominance where alleles blend, codominance results in both alleles being fully expressed.

* Distinct Phenotype: The phenotype is a combination of both alleles, not a blend.

* No Recessive Allele: There's no "recessive" allele in codominance. Both alleles contribute equally.

Other Examples of Codominance:

* Roan Cattle: Roan cattle have a coat color that is a mixture of red and white hairs, resulting from the co-expression of red and white fur alleles.

* Flower Color: Certain flower species have codominant alleles for color, resulting in flowers with patches of different colors.

Key Points to Remember:

* Codominance is a unique inheritance pattern where both alleles are expressed equally.

* It results in a phenotype that exhibits both alleles distinctly.

* It is different from incomplete dominance where alleles blend to produce an intermediate phenotype.

Let me know if you'd like more details on any of these aspects!