1. Dominant trait: If one allele is dominant, the trait associated with that allele will be expressed, regardless of the other allele. The other allele is considered recessive and its trait is masked.
2. Codominant trait: If both alleles are codominant, both traits will be expressed simultaneously. This means neither allele masks the other, and the offspring will have a phenotype that combines both parental traits.
Examples:
* Eye color: Brown eyes are dominant to blue eyes. So, if someone has one allele for brown eyes and one for blue eyes, they will have brown eyes.
* Blood type: The ABO blood group system is an example of codominance. If someone has an allele for blood type A and an allele for blood type B, they will have blood type AB, which exhibits both A and B antigens.
Therefore, the specific trait expressed when two different alleles are present depends on whether the alleles are dominant, recessive, or codominant.
