What is a classic example of codominance?

What is a classic example of codominance?

• A. The phenotype of pink flowers from red and white parents
• B. The ABO blood group system in humans
• C. A mixture of traits from two parents
• D. Individual gene expressions that suppress others

Answer: (B)

Codominance occurs when both alleles in a heterozygous individual contribute equally and visibly to the organism's phenotype, without one being dominant over the other. The ABO blood group system in humans serves as a classic example of this genetic phenomenon. In this system, individuals can have A, B, AB, or O blood types depending on the combination of alleles inherited from their parents. The A and B alleles are codominant, meaning if a person inherits one A allele and one B allele, both are fully expressed, resulting in the AB blood type. This clear and observable expression of both traits highlights how codominance operates. Other options describe different genetic concepts. For instance, the mention of pink flowers arising from red and white parents points to incomplete dominance, where the phenotype of the offspring is a blend of the two parental traits, rather than an equal expression of both. A mixture of traits from two parents could generally describe various inheritance patterns, but it doesn't specifically denote codominance. Furthermore, individual gene expressions that suppress others typically refer to epistasis, where one gene can mask or conceal the expression of another, contrasting with the concept of codominance.

Codominance occurs when both alleles in a heterozygous individual contribute equally and visibly to the organism's phenotype, without one being dominant over the other. The ABO blood group system in humans serves as a classic example of this genetic phenomenon. In this system, individuals can have A, B, AB, or O blood types depending on the combination of alleles inherited from their parents. The A and B alleles are codominant, meaning if a person inherits one A allele and one B allele, both are fully expressed, resulting in the AB blood type. This clear and observable expression of both traits highlights how codominance operates.

Other options describe different genetic concepts. For instance, the mention of pink flowers arising from red and white parents points to incomplete dominance, where the phenotype of the offspring is a blend of the two parental traits, rather than an equal expression of both. A mixture of traits from two parents could generally describe various inheritance patterns, but it doesn't specifically denote codominance. Furthermore, individual gene expressions that suppress others typically refer to epistasis, where one gene can mask or conceal the expression of another, contrasting with the concept of codominance.