Question: Expression of both the alleles of a gene in F₁ refers to: (JFR Plant Science 2018)
Options:
Partial dominance
Incomplete dominance
Co-dominance
None of these
✅ Explanation:
-Co-dominance: This occurs when both alleles of a gene are fully expressed in the heterozygous condition (F₁ generation). Neither allele masks the effect of the other; instead, both contribute equally to the phenotype.
-Distinct Phenotype: The resulting phenotype in co-dominance is not a blend of the two parental traits (as in incomplete dominance) but rather a distinct expression of both traits simultaneously.
-Classic Example: ABO Blood Group: The ABO blood group system in humans is a classic example of co-dominance. Individuals with the AB blood type have both A and B antigens on their red blood cells, demonstrating the full expression of both alleles.
-Co-dominance: This occurs when both alleles of a gene are fully expressed in the heterozygous condition (F₁ generation). Neither allele masks the effect of the other; instead, both contribute equally to the phenotype.
-Distinct Phenotype: The resulting phenotype in co-dominance is not a blend of the two parental traits (as in incomplete dominance) but rather a distinct expression of both traits simultaneously.
-Classic Example: ABO Blood Group: The ABO blood group system in humans is a classic example of co-dominance. Individuals with the AB blood type have both A and B antigens on their red blood cells, demonstrating the full expression of both alleles.
✏️Other Examples:
-Roan Coat Color in Cattle: Where both red and white hairs are present.
-Seed Coat Patterns in Some Plants: Where both parental patterns are visible.
📌 Other Options Explanations:
-Partial dominance: A situation where the dominant allele doesn't completely mask the recessive allele, resulting in an intermediate phenotype.
-Incomplete dominance: Similar to partial dominance, where the heterozygote shows a blended phenotype.